CN114878048A - Method for detecting effective prestress under steel strand anchor after grouting - Google Patents
Method for detecting effective prestress under steel strand anchor after grouting Download PDFInfo
- Publication number
- CN114878048A CN114878048A CN202210496899.5A CN202210496899A CN114878048A CN 114878048 A CN114878048 A CN 114878048A CN 202210496899 A CN202210496899 A CN 202210496899A CN 114878048 A CN114878048 A CN 114878048A
- Authority
- CN
- China
- Prior art keywords
- steel strand
- grouting
- driving force
- displacement
- prestressed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0028—Force sensors associated with force applying means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0003—Steady
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0017—Tensile
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0676—Force, weight, load, energy, speed or acceleration
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0682—Spatial dimension, e.g. length, area, angle
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Piles And Underground Anchors (AREA)
Abstract
The invention discloses a method for detecting effective prestress under a steel strand anchor after grouting, which is applied to grouting of a grouting channel where a prestress steel strand (2) is located; the method comprises the following steps: s1, detecting the length L of a free section of a prestressed steel strand (2) exposed out of a grouting body (10); s2, extracting a target deformation quantity delta L after the deformation quantity is subjected to first jump change and a corresponding reverse pulling driving force F; and S3, calculating an elastic deformation correcting force Fx according to the length dimension L and the target deformation quantity delta L, wherein Fx is delta L/L E A, calculating an effective prestress Fy under the grouted steel strand anchor according to the elastic deformation correcting force Fx and a reverse pulling driving force F, wherein Fy is F-Fx, A is the cross-sectional area of the stress steel strand (2), and E is the elastic modulus of the prestress steel strand (2). The method for detecting the effective prestress under the steel strand anchor is executed after grouting so as to achieve the technical problem of avoiding cross interference in detection construction and engineering construction.
Description
Technical Field
The invention relates to the technical field of prestress detection, in particular to a method for detecting effective prestress under a steel strand anchor after grouting.
Background
The prestressed concrete is a concrete member, mainly used in building engineering and bridge engineering. The pre-stress is used for reducing or offsetting the tensile stress of the concrete caused by the load, so that the tensile stress of the structural member is controlled in a smaller range and even in a compressed state, the occurrence and development of concrete cracks are delayed, and the crack resistance and the rigidity of the member are improved.
Prestressed concrete is classified into pretensioned prestressed concrete and post-tensioned prestressed concrete. Referring to the attached drawings 1 and 2, the prestressed concrete 1 of the post-tensioning prestressed concrete comprises a concrete body, a grouting pore channel positioned in the concrete body, prestressed steel strands 2 positioned in the grouting pore channel, anchors 3 fixed on two sides of the concrete body, and anchor clips 4 in the anchors 3 clamp two ends of the prestressed steel strands 2.
The construction sequence of the post-tensioning prestressed concrete is as follows: pouring to form a concrete body, penetrating prestressed steel strands 2 in a grouting pore channel reserved in the concrete body, fixing two ends of the prestressed steel strands 2 by using an anchorage device 3, applying pulling force to the prestressed steel strands 2 by using jacks on two sides simultaneously to enable the prestressed steel strands 2 to form prestress, then grouting in the grouting pore channel, and locking the prestressed steel strands by using a grouting body formed by grouting.
In order to detect whether qualified prestress is applied in the construction process, the prestress steel strand 2 is generally in a free state before grouting, and the adopted method includes a reverse pulling method, for example: patent application 201811646344.4, which teaches: before grouting, when the prestressed steel strand 2 is not locked by the grouting body 10, the length of the free section of the prestressed steel strand 2 is 10m, under the counter-pulling method, the pulling displacement of the prestressed steel strand 2 is set to be delta L, according to the formula Fs, the pulling displacement is set to be delta L/L E A, the delta L is set to be 0.5mm-2.5mm, the L is set to be 10 m-10000 mm, and the E is set to be 195000N/mm 2 Taking A as 140mm 2 In this case, Fs was 1.365KN-6.825KN, and Fs was the influence of the displacement amount on the prestress. Thus, it can be derived: when the free section is long, i.e., L is long, Fs can be ignored,directly taking the counter-pulling force as the effective prestress under the steel strand anchor, see the patent, which proposes: directly taking the counter-pulling force F when the displacement S is stabilized at a constant value as the effective prestress value Fy under the anchor head.
That is, patent application 201811646344.4 proposes a method for detecting the effective prestressing of a steel strand anchor prior to grouting.
Generally, in the field, after grouting, the prestressed steel strand 2 is locked by the grouting body 10, so that prestress detection cannot be performed by adopting a reverse pulling method, referring to fig. 2, full grouting material is generally filled in a grouting hole according to a standard requirement, so that theoretically, the prestressed steel strand 2 inside the grouting body is completely locked by the grouting body 10, and detection of effective prestress under the anchor cannot be performed at this time, therefore, existing prestress detection methods are required to be completed before grouting, and are complicated to add to the existing prestress detection methods, therefore, in many projects, supervision and management are performed when prestress is applied to ensure the quality of the project, and prestress detection is often not performed or grouting treatment is performed after partial sampling inspection is qualified.
That is, the existing method for detecting the prestress before grouting is not friendly to engineering construction and needs to occupy a large amount of construction period time for adoption.
Therefore, a method for detecting the effective prestress under the steel strand anchor after the detection time is shifted backwards to the grouting construction is needed to achieve the technical problems that the quality detection can be realized while the better engineering construction time benefit is achieved, and the cross interference between the detection construction and the engineering construction is avoided.
Disclosure of Invention
The invention aims to provide a method for detecting effective prestress under a steel strand anchor after grouting so as to achieve the technical problem of avoiding cross interference in detection construction and engineering construction.
In order to realize the detection of the effective prestress under the steel strand anchor after grouting, the invention provides the following steps: the method comprises the steps of utilizing the size of the inherent mud jacking defect of the post-tensioning prestressed concrete process to be marked as the size of a free section of a prestressed steel strand, utilizing the counter-pulling method to detect the balance state to obtain a counter-pulling driving force, utilizing the size of the free section to calculate the elastic deformation correcting force of the free section and correct the counter-pulling driving force, and finally obtaining the effective prestress under the steel strand anchor.
In order to solve the technical problem, the invention adopts the following scheme:
the method for detecting the effective prestress under the steel strand anchor after grouting acts on prestressed concrete, wherein the prestressed concrete comprises a concrete body, a grouting pore channel positioned in the concrete body, prestressed steel strands positioned in the grouting pore channel, anchors fixed on two sides of the concrete body, and anchor clamping pieces in the anchors clamp two ends of each prestressed steel strand; the method is applied to grouting of the grouting pore where the prestressed steel strand is located; the method comprises the following steps:
s1, after grouting a grouting hole where a prestressed steel strand is located to form grouting body, detecting the length dimension L of a free section of the prestressed steel strand exposed outside the grouting body;
s2, after grouting in a grouting channel where the prestressed steel strands are located to form grouting body, applying a reverse-pulling driving force which is gradually increased from the inside of prestressed concrete to the outside to the prestressed steel strands, recording deformation quantities of the prestressed steel strands and the corresponding reverse-pulling driving forces, extracting a target deformation quantity Delta L after the deformation quantities are subjected to first jumping and a corresponding reverse-pulling driving force F, and determining that the deformation quantities are subjected to first jumping as controllable elastic deformation jumping in a free section of the prestressed steel strands exposed outside the grouting body;
and S3, calculating an elastic deformation correction force Fx according to the length dimension L and the target deformation quantity delta L, wherein Fx is delta L/L E A, calculating an effective prestress Fy under the steel strand anchor after grouting according to the elastic deformation correction force Fx and a reverse pulling driving force F, Fy is F-Fx, A is the section area of the stress steel strand, and E is the elastic modulus of the prestress steel strand.
The design principle of the invention is as follows:
referring to fig. 2, in theoretical engineering, full grouting material is generally filled in a grouting hole according to the specification requirement, so theoretically, the prestressed steel strand inside the grouting hole is completely locked by the grouting body, and therefore, in the field, it is generally considered that detection of effective prestress under the anchor cannot be performed after grouting.
Referring to fig. 3, since the prestressed concrete has an arch-shaped characteristic, after grouting, the areas at both ends of the prestressed steel strand form a defect due to gravity, which is difficult to avoid, and the defect is characterized in the present invention as follows: the inherent grouting defect of the post-tensioning prestressed concrete process. Therefore, in practical engineering, there are some segments at both ends of the prestressed steel strand that are not locked by the grouting body, and therefore, there is a possibility that the segments are prestressed by the pull-back detection, and the segments of the prestressed steel strand that are not locked by the grouting body are defined as follows: the prestressed steel strand is exposed at the free section outside the grouting body.
Referring to fig. 1 and patent application 201811646344.4, which are tests performed when the steel strand is not grouted, the free section is the entire prestressed steel strand, and therefore, in the system, Fs ═ Δ L/L × E ×, it can be seen that: since L is much larger than Δ L, Fs is smaller and does not affect the counter-pulling force.
Referring to fig. 4 and 5, in the system of the present invention, the present invention is performed after grouting, most areas of the prestressed steel strands in the system are locked by the grouting body, and only the prestressed steel strands in the inherent grouting defect of the post-tensioned prestressed concrete process are in a free state, so that L in Fs ═ Δ L/L × E a is sharply reduced from a large value in the prior art to a small value, and therefore, the present invention applies a reverse pulling driving force F to the system, and at this time, Fs needs to be added to correct the driving force F, and the corrected result can be qualified as effective prestress under the steel strand anchor.
Therefore, the technical principle of the invention is as follows: and applying counter-pulling force to the free section of the prestressed steel strand exposed outside the grouting body due to the defects of the grouting process, so as to obtain the counter-pulling force when the deformation quantity is stabilized at a constant value after the free section is deformed (the anchor clamping piece is loosened at the moment). At the moment, the whole system is in a balanced state, and the reverse pulling driving force F at the moment is reversely equal to the sum of the effective prestress F under the steel strand anchor and the extension load force (the elastic deformation correcting force Fx ═ Fs) of the free section exposed outside the grouting body. In the invention, considering that the free section outside the grouting body is small, the extension load force of the free section exposed outside the grouting body is large at the moment, and the influence on the counter-tension is large, the extension load force of the free section exposed outside the grouting body needs to be regarded as the elastic deformation correction force Fx, the counter-tension driving force F is corrected by the elastic deformation correction force Fx, and finally the effective prestress Fy under the steel strand anchor after grouting is obtained.
It should be noted that:
in S2, the reverse-pulling driving force is gradually increased from the inside of the prestressed concrete to the outside, in the gradually increasing process, the deformation amount of the prestressed steel strand does not change or does not change obviously at the beginning, when F is larger than the sum of the effective prestress Fy under the steel strand anchor after grouting, the frictional resistance Fj of an anchor clip and the anchor and the elongation load force Fx (elastic deformation correction force Fx) of a free section exposed outside the grouting body, the deformation amount of the prestressed steel strand changes obviously, and the deformation amount is regarded as the first jump of the deformation amount; this amount of deformation can be monitored using displacement monitoring techniques. Since the frictional resistance Fj disappears after the first transition, the reverse pull-back driving force needs to be controlled to fall back in order to maintain the deformation amount. Therefore, the control system of the reverse pulling driving force adopted by the invention is a dynamic balance control system for maintaining the deformation quantity. The required reverse pulling driving force F is F in the balanced state, and the deformation quantity in the balanced state is the required target deformation quantity DeltaL.
Therefore, the invention takes the defect as an unfavorable element in engineering to reversely pull the prestressed steel strand in the defect, can measure the defect by using an echo method and calibrate the free section so as to obtain the correction quantity, and obtains the actual nearest effective prestress under the steel strand anchor after the force of the reverse-pull balance system is corrected.
The method can provide a method for effectively detecting the effective prestress under the steel strand anchor after grouting, and can avoid the problem of cross interference with engineering construction.
Further, in the above-mentioned case,
the specific process for detecting the length dimension L of the free section of the prestressed steel strand exposed outside the grouting body comprises the following steps:
grouting a grouting hole where the prestressed steel strand is located to form grouting body, performing grouting defect detection on the grouting hole where the prestressed steel strand is located by using grouting defect detection equipment, screening out grouting defects adjacent to an anchorage device from the grouting defects to be inherent grouting defects of a post-tensioning prestressed concrete process, obtaining the length dimension L1 of the inherent grouting defects of the post-tensioning prestressed concrete process, and regarding the length dimension L1 as a first free section of the prestressed steel strand;
measuring the length dimension L2 of an anchor clip positioned in the anchor, and regarding the length dimension L2 as a second free section of the prestressed steel strand;
measuring the length dimension L3 of the prestressed steel strand positioned outside the anchor clamping piece, and regarding the length dimension L3 as a third free section of the prestressed steel strand;
the length dimension L of the free section of the prestressed steel strand exposed outside the grouting body is as follows: l1 or L1+ L2 or L1+ L2+ L3.
Further, in the above-mentioned case,
the specific process of applying the reverse pulling driving force which is gradually increased from the inside of the prestressed concrete to the outside to the prestressed steel strand is as follows:
and adopting reverse-pulling equipment to connect the part of the prestressed steel strand exposed outside the anchor clamping piece and applying a gradually increased reverse-pulling driving force to the prestressed steel strand from the inside of the prestressed concrete to the outside.
Further, in the above-mentioned case,
the reverse pulling equipment is used for controlling the reverse pulling driving force to exceed a set driving force safety limit value or stopping increasing the reverse pulling driving force when the displacement exceeds a set displacement safety limit value.
Further, in the above-mentioned case,
the counter-pulling equipment comprises: the device comprises a displacement measuring tool, a bridge type pressure sensor, a driving jack, a displacement recorder, a reverse-pulling driving force recorder and a reverse-pulling driving force controller;
the displacement measurement tool comprises a displacement measurement sleeve barrel, a displacement transmission mechanism arranged at the eccentric position of the displacement measurement sleeve barrel, and a displacement sensor for sensing the displacement transmission mechanism;
the driving jack comprises a jack static part and a jack action part;
the prestressed steel strand positioned outside the anchor clamping piece penetrates through the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part and the jack action part;
one end of the displacement measuring sleeve body is pressed against the outer side surface of the anchorage device, and the displacement transmission mechanism is initially contacted with the anchorage device clamping piece; the other end of the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part and the jack action part are sequentially and coaxially connected, the jack action part clamps the prestressed steel strand, and the jack action part is driven by the jack static part to apply a counter-pulling driving force which is gradually increased from the inside of the prestressed concrete to the outside;
the displacement recorder is connected with the displacement sensor and records a displacement value, and the displacement value is regarded as the deformation quantity of the prestressed steel strand;
the counter-pulling driving force recorder is connected with the bridge type pressure sensor and records a pressure value, and the pressure value is regarded as a counter-pulling driving force corresponding to the deformation amount of the prestressed steel strand;
the reverse-pulling driving force controller controls the static part of the jack to apply a gradually increased reverse-pulling driving force from the inside of the prestressed concrete to the outside to the action part of the jack;
and the reverse pulling driving force controller controls the reverse pulling driving force to stop increasing the reverse pulling driving force when the reverse pulling driving force exceeds a set driving force safety limit value or the displacement exceeds a set displacement safety limit value.
Further, in the above-mentioned case,
the counter-pulling equipment comprises: the device comprises an extension steel strand, a connector, a displacement measuring tool, a bridge type pressure sensor, a driving jack, a displacement recorder, a counter-pull driving force recorder and a counter-pull driving force controller;
the displacement measurement tool comprises a displacement measurement sleeve barrel, a displacement transmission mechanism arranged at the eccentric position of the displacement measurement sleeve barrel, and a displacement sensor for sensing the displacement transmission mechanism;
the driving jack comprises a jack static part and a jack action part;
the connector comprises a connector outer sealing body and a connecting block, wherein a prestressed steel strand positioned outside an anchorage device clamping piece is inserted into the connecting block, one end of an extension steel strand is inserted into the connecting block, one end of the connector outer sealing body is pressed against the outer side surface of the anchorage device, the connecting block is arranged inside the connector outer sealing body and can move, the other end of the connector outer sealing body is pressed against by a displacement measuring sleeve body, and initially, a displacement transmission mechanism is contacted with the connecting block;
the other end of the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part and the jack action part are sequentially and coaxially connected, the extension steel stranded wire sequentially penetrates through the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part and the jack action part, the jack action part clamps the extension steel stranded wire, and the jack action part is driven by the jack static part to apply a reverse-pulling driving force which is gradually increased from the inner part of the prestressed concrete to the outside;
the displacement recorder is connected with the displacement sensor and records a displacement value, and the displacement value is regarded as a deformation quantity of the prestressed steel strand;
the counter-pulling driving force recorder is connected with the bridge type pressure sensor and records a pressure value, and the pressure value is regarded as a counter-pulling driving force corresponding to the deformation amount of the prestressed steel strand;
the reverse-pulling driving force controller controls the static part of the jack to apply a gradually increased reverse-pulling driving force from the inside of the prestressed concrete to the outside to the actuating part of the jack;
and the reverse pulling driving force controller controls the reverse pulling driving force to stop increasing the reverse pulling driving force when the reverse pulling driving force exceeds a set driving force safety limit value or the displacement exceeds a set displacement safety limit value.
Further, in the above-mentioned case,
the connecting block includes: stud, left sleeve, left clamping piece, right sleeve, right clamping piece, establish left clamping piece in the left sleeve, establish right clamping piece in the right sleeve, be located the outside prestressing force steel strand wires of ground tackle clamping piece insert in the left clamping piece, the one end of extension steel strand wires inserts in the right clamping piece, and left sleeve, right sleeve are inserted respectively to the stud both ends.
Further, in the above-mentioned case,
the concrete process of carrying out grouting defect detection on the grouting channel where the prestressed steel strand is located by adopting grouting defect detection equipment comprises the following steps: and distributing points along the measuring lines on the top plate or the bottom plate corresponding to the grouting pore channel where the prestressed steel strands are located, and performing data acquisition on the measuring lines by adopting an impact echo method and analyzing the grouting defects of the grouting pore channel.
Further, in the above-mentioned case,
the target deformation quantity delta L is adjusted and increased along with the increase of the length L of the free section of the stress steel strand exposed outside the grouting body.
Further, in the above-mentioned case,
the target deformation quantity Delta L is adjusted to be 1mm-2 mm.
The invention has the following beneficial effects: the invention provides a method for effectively detecting the effective prestress under the steel strand anchor after grouting, which can avoid the problem of cross interference with engineering construction.
Drawings
Fig. 1 is a schematic diagram illustrating an effective prestress detection performed by a reverse pulling method before grouting in the prior art.
Fig. 2 is a schematic view of a theoretical state of a prestressed concrete structure.
Fig. 3 is a schematic view of a prestressed concrete structure in an actual state.
FIG. 4 is a schematic view of an initial state of effective prestress detection by a reverse pulling method after grouting according to the present invention.
FIG. 5 is a schematic view of the equilibrium state of the effective prestress detection by the reverse pulling method after grouting according to the present invention.
FIG. 6 is a schematic diagram of the control system of the present invention.
FIG. 7 is a schematic flow chart of the present invention.
Fig. 8 is a diagram showing the relationship between the amount of deformation after the counter-pulling driving force is in an equilibrium state after the amount of deformation reaches the target amount of deformation by increasing the counter-pulling driving force.
The reference numerals are explained below: 1. prestressed concrete, 2, prestressed steel strands, 3, an anchorage device, 4, anchorage device clamping pieces, 5, a displacement measuring tool, 6, a displacement transmission mechanism, 7, a displacement sensor, 8, a jack static part, 9, a jack action part, 10, a grouting body, 11, an extension steel strand, 12, a connector outer sealing body, 13, a stud bolt, 14, a left sleeve, 15, a left clamping piece, 16, a right sleeve, 17, a right clamping piece and 18.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited to these examples.
Example 1
Referring to fig. 1 to 8:
the method for detecting the effective prestress under the steel strand anchor after grouting acts on prestressed concrete 1, and is shown in the attached drawing 4, wherein the prestressed concrete 1 comprises a concrete body, a grouting pore channel positioned in the concrete body, prestressed steel strands 2 positioned in the grouting pore channel, anchors 3 fixed on two sides of the concrete body, and two ends of each prestressed steel strand 2 are clamped by anchor clamps 4 in the anchors 3; the method is applied to grouting of the grouting hole where the prestressed steel strand 2 is located; referring to fig. 7, the method comprises the following steps:
s1, after grouting a grouting body 10 formed by grouting a grouting channel where a prestressed steel strand 2 is located, detecting the length dimension L of a free section of the prestressed steel strand 2 exposed out of the grouting body 10;
s2, after grouting a grouting hole where the prestressed steel strand 2 is located to form a grouting body 10, applying a reverse-pulling driving force which is gradually increased from the inside of prestressed concrete to the outside to the prestressed steel strand 2, recording the deformation amount of the prestressed steel strand 2 and the corresponding reverse-pulling driving force, extracting a target deformation amount delta L after the deformation amount is subjected to first jump and a corresponding reverse-pulling driving force F, and qualitatively performing the first jump on the deformation amount to perform controllable elastic deformation jump on a free section of the prestressed steel strand 2 exposed out of the grouting body 10;
and S3, calculating an elastic deformation correction force Fx according to the length dimension L and the target deformation quantity delta L, wherein Fx is delta L/L E A, calculating an effective prestress Fy under the steel strand anchor after grouting according to the elastic deformation correction force Fx and a reverse pulling driving force F, wherein Fy is F-Fx, A is the section area of the stress steel strand 2, and E is the elastic modulus of the prestress steel strand 2.
Referring to fig. 8, the present invention employs counter-pulling to pull the pre-stressed steel strand 2 outward. In order to avoid damage to the prestressed steel strand 2, when a reverse-pulling driving force is applied to the prestressed steel strand 2, the reverse-pulling driving force is gradually increased, because the anchor clamping piece 4 exists in the system, if the anchor clamping piece 4 is pulled, the reverse-pulling driving force is larger than the effective prestress under the steel strand anchor, the deformation quantity of the prestressed steel strand 2 is subjected to a first jump phenomenon, if the reverse-pulling driving force is continuously increased later, the prestressed steel strand is easily damaged, therefore, a target deformation quantity DeltaL needs to be set, after the target deformation quantity DeltaL is detected, the reverse-pulling driving force stops increasing or starts self-feedback balance, namely, the reverse-pulling driving force is output by taking the target deformation quantity DeltaL as a target, the reverse-pulling driving force at the moment is the reverse-pulling driving force F searched by the invention, and referring to FIG. 8, the drawing shows that the deformation quantity is maintained at a stable value after the first jump occurs, namely, the target deformation quantity Δ L in the graph, which simultaneously shows that the reverse-pull driving force is at a stable value after a fall-back from a high position, and the stable value is the reverse-pull driving force F. The invention adopts a counter-pulling balance method to find a counter-pulling driving force F, and the counter-pulling driving force F is corrected and then used as the effective prestress Fy under the steel strand anchor after grouting.
The design principle of the invention is as follows:
referring to fig. 2, in theoretical engineering, full grouting material is generally filled in a grouting hole according to the specification requirement, so theoretically, the prestressed steel strand 2 inside the grouting hole is completely locked by the grouting body 10, and therefore, in the field, it is generally considered that detection of effective prestress under the anchor cannot be performed after grouting.
Referring to fig. 3, since the prestressed concrete has an arch-shaped characteristic, after grouting, the areas at both ends of the prestressed steel strand 2 form a defect due to gravity, which is difficult to avoid, and the defect is characterized in the present invention as follows: the post-tensioned prestressed concrete process has inherent grouting defects 18. Therefore, in practical engineering, there are some segments at both ends of the prestressed steel strand 2 that are not locked by the grout 10, and therefore, there is a possibility that the segments can be pre-stressed by the reverse pull detection, and the segments of the prestressed steel strand 2 that are not locked by the grout 10 are defined as follows: the prestressed steel strand 2 is exposed out of the grouting body 10 at a free section.
With reference to fig. 1 and patent application 201811646344.4, which is a test when it is not grouted, the free section of which is the entire prestressed steel strand 2, and therefore under its system, Fs ═ Δ L/L × E ×, a is observed, and it can be seen that: since L is much larger than Δ L, Fs is smaller and does not affect the back tension, therefore, this prior art does not use Fs, but uses the count of the bridge pressure sensor directly as the effective pre-stress Fy under the anchor.
Referring to fig. 3, 4 and 5, in the system of the present invention, the present invention is performed after grouting, most areas of the prestressed steel strands 2 in the system are locked by the grouting body 10, only the prestressed steel strands 2 in the inherent grouting defect 18 of the post-tensioned prestressed concrete process are in a free state, and therefore, L in Fs ═ Δ L/L × a is sharply reduced from a large value in the prior art to a small value, and therefore, the present invention applies a reverse pulling driving force F to the system, and at this time, Fs needs to be added to correct the L, and the corrected result can be qualified as effective prestress under the steel strand anchor.
Therefore, the technical principle of the invention is as follows: and exerting counter-pulling force on a free section of the prestressed steel strand 2 exposed out of the grouting body 10 due to the defects of the grouting process, so as to obtain the counter-pulling force when the deformation quantity is stabilized at a constant value after the free section is deformed (at the moment, the anchorage device clamping piece 4 is loosened). At this time, the whole system is in a balanced state, and the reverse pulling driving force F at this time is reversely equal to the sum of the effective prestress F under the steel strand anchor and the extension load force (elastic deformation correcting force Fx ═ Fs) of the free section exposed out of the grouting body 10. In the present invention, considering that the free section outside the grouting body 10 is small, the elongation load force of the free section exposed outside the grouting body 10 is large at this time, and the influence on the counter-pulling force is large, the elongation load force of the free section exposed outside the grouting body 10 needs to be regarded as the elastic deformation correction force Fx, the counter-pulling driving force F is corrected by the elastic deformation correction force Fx, and finally the effective prestress Fy under the steel strand anchor after grouting is obtained.
It should be noted that:
in S2, the reverse-pulling driving force is gradually increased from the inside of the prestressed concrete to the outside, in the gradually increasing process, the deformation amount of the prestressed steel strand 2 does not change or does not change at first, when F is larger than the sum of the effective prestress Fy under the steel strand anchor after grouting, the frictional resistance Fj of the anchor clip 4 and the anchor and the elongation load force Fx (elastic deformation correcting force Fx) of the free section exposed out of the grouting body 10, the deformation amount of the prestressed steel strand 2 changes obviously, and the deformation amount is regarded as the first jump of the deformation amount; this amount of deformation can be monitored using displacement monitoring techniques. Since the frictional resistance Fj disappears after the first transition, the reverse pull-back driving force needs to be controlled to fall back in order to maintain the deformation amount. Therefore, the control system of the reverse pulling driving force adopted by the invention is a dynamic balance control system for maintaining the deformation quantity. The required reverse pulling driving force F is F in the balanced state, and the deformation quantity in the balanced state is the required target deformation quantity DeltaL.
Therefore, the invention takes the defect as an unfavorable element in engineering to reversely pull the prestressed steel strand 2 in the defect, can measure the defect by using an echo method and calibrate the free section so as to obtain a correction amount, and obtains the actual nearest effective prestress under the steel strand anchor after the force of the reverse-pull balance system is corrected.
The method can provide a method for effectively detecting the effective prestress under the steel strand anchor after grouting, and can avoid the problem of cross interference with engineering construction.
Example 2
On the basis of the foregoing embodiment 1, a specific process of detecting the length dimension L of the free section of the prestressed steel strand 2 exposed out of the grouting body 10 is as follows:
after grouting a grouting hole in which the prestressed steel strand 2 is located to form grouting body 10, grouting defect detection is carried out on the grouting hole in which the prestressed steel strand 2 is located by grouting defect detection equipment, grouting defects adjacent to an anchorage device 3 are screened out from the grouting defects to be inherent grouting defects 18 of the post-tensioning prestressed concrete process, the length dimension L1 of the inherent grouting defects 18 of the post-tensioning prestressed concrete process is obtained, and the length dimension L1 is regarded as a first free section of the prestressed steel strand 2;
measuring the length dimension L2 of an anchor clip 4 positioned in the anchor, and regarding the length dimension L2 as a second free section of the prestressed steel strand 2;
measuring the length dimension L3 of the prestressed steel strand 2 positioned outside the anchor clip 4, and regarding the length dimension L3 as a third free section of the prestressed steel strand 2;
the length L of the free section of the prestressed steel strand 2 exposed out of the grouting body 10 is as follows: l1 or L1+ L2 or L1+ L2+ L3.
It should be noted that:
referring to fig. 4 of the drawings, in fig. 4, the system of the drawings is shown in which the prestressed steel strands 2 within the post-tensioned prestressed concrete process-inherent mudjacking flaws 18 are prestressed, the prestressed steel strands 2 held by the anchor jaws 4 are prestressed, and the prestressed steel strands 2 outside the anchor jaws 4 are not prestressed. Meanwhile, in the system, because the prestressed steel strand 2 positioned outside the anchor clamping piece 4 is cut off and is shorter at the moment, and a counter-pulling force is conveniently applied, a connector needs to be designed to be connected with an extension steel strand, so that the counter-pulling force can be conveniently applied to the counter-pulling equipment, referring to fig. 4, the drawing illustrates the extension steel strand and the counter-pulling equipment matched with the extension steel strand, and at the moment, the prestressed steel strand 2 positioned outside the anchor clamping piece 4 is clamped without deformation characteristics, so that in the drawing, L1 and L2 are marked, and the length L of a free section of the prestressed steel strand 2 exposed out of the grouting body 10 is L1+ L2; that is, since the connector shown in fig. 4 is used to connect the exposed section of the prestressed steel strand 2 exposed outside the anchor clip 4, the section L3 does not participate in L.
In addition, when the anchor clamping pieces 4 are short, i.e. in some small prestressed concrete, the anchor clamping pieces 4 are negligible when being small, so that the length dimension L of the free section of the prestressed steel strand 2 exposed out of the grouting body 10 is L1.
In addition, when the prestress steel strand 2 positioned outside the anchor clamping piece 4 is not clamped by the connecting body, an extension steel strand is connected by adopting a welding mode, or the extension steel strand is not cut and is sufficient to apply counter tension, so that the consideration of L3 is needed to be taken into the calculation, and at the moment, the length L of the free section of the prestress steel strand 2 exposed out of the grouting body 10 is L1+ L2+ L3.
Example 3
On the basis of the above embodiment, referring to fig. 4 and 5, the specific process of applying the gradually increasing reverse pulling driving force from the inside of the prestressed concrete to the outside to the prestressed steel strand 2 is as follows:
and adopting reverse-pulling equipment to connect the part of the prestressed steel strand 2 exposed outside the anchorage device clamping piece 4 and applying a gradually increased reverse-pulling driving force to the prestressed steel strand 2 from the inside of the prestressed concrete to the outside.
Further, in the above-mentioned case,
the reverse pulling equipment is used for controlling the reverse pulling driving force to exceed a set driving force safety limit value or stopping increasing the reverse pulling driving force when the displacement exceeds a set displacement safety limit value.
Further, in the above-mentioned case,
the counter-pulling equipment comprises: the device comprises a displacement measuring tool 5, a bridge type pressure sensor, a driving jack, a displacement recorder, a reverse-pulling driving force recorder and a reverse-pulling driving force controller;
the displacement measuring tool 5 comprises a displacement measuring sleeve body, a displacement transmission mechanism 6 arranged at the eccentric position of the displacement measuring sleeve body and a displacement sensor 7 for sensing the displacement transmission mechanism 6;
the driving jack comprises a jack static part 8 and a jack action part 9;
the prestressed steel strand 2 positioned outside the anchor device clamping piece 4 penetrates through the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part 8 and the jack action part 9;
one end of the displacement measuring sleeve body is pressed against the outer side surface of the anchorage device, and the displacement transmission mechanism 6 is initially contacted with the anchorage device clamping piece 4; the other end of the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part 8 and the jack action part 9 are sequentially and coaxially connected, the jack action part 9 clamps the prestressed steel strand 2, and the jack action part 9 is driven by the jack static part 8 to apply a reverse-pulling driving force which is gradually increased from the inside of the prestressed concrete to the outside;
as shown in figure 6 of the drawings,
the displacement recorder is connected with the displacement sensor 7 and records a displacement value, and the displacement value is regarded as a deformation quantity of the prestressed steel strand 2;
the counter-pulling driving force recorder is connected with the bridge type pressure sensor and records a pressure value, and the pressure value is regarded as a counter-pulling driving force corresponding to the deformation amount of the prestressed steel strand 2;
the reverse-pulling driving force controller controls the jack static part 8 to apply a gradually increased reverse-pulling driving force from the inner part of the prestressed concrete to the outer part to the jack action part 9;
and the reverse pulling driving force controller controls the reverse pulling driving force to stop increasing the reverse pulling driving force when the reverse pulling driving force exceeds a set driving force safety limit value or the displacement exceeds a set displacement safety limit value.
Example 4
On the basis of the above embodiment, referring to fig. 4 and 5, the specific process of applying the gradually increasing reverse pulling driving force to the prestressed steel strand 2 from the inside of the prestressed concrete to the outside is as follows:
and adopting reverse-pulling equipment to connect the part of the prestressed steel strand 2 exposed outside the anchorage device clamping piece 4 and applying a gradually increased reverse-pulling driving force to the prestressed steel strand 2 from the inside of the prestressed concrete to the outside.
Further, in the above-mentioned case,
the reverse pulling equipment is used for controlling the reverse pulling driving force to exceed a set driving force safety limit value or stopping increasing the reverse pulling driving force when the displacement exceeds a set displacement safety limit value.
The counter-pulling equipment comprises: the device comprises an extension steel strand 11, a connector, a displacement measuring tool 5, a bridge type pressure sensor, a driving jack, a displacement recorder, a counter-pull driving force recorder and a counter-pull driving force controller;
the displacement measuring tool 5 comprises a displacement measuring sleeve body, a displacement transmission mechanism 6 arranged at the eccentric position of the displacement measuring sleeve body and a displacement sensor 7 for sensing the displacement transmission mechanism 6;
the driving jack comprises a jack static part 8 and a jack action part 9;
the connector comprises a connector outer sealing body 12 and a connecting block, wherein a prestressed steel strand 2 positioned outside an anchor clamping piece 4 is inserted into the connecting block, one end of an extension steel strand 11 is inserted into the connecting block, one end of the connector outer sealing body 12 is propped against the outer side surface of the anchor, the connecting block is arranged in the connector outer sealing body 12 and can move, the other end of the connector outer sealing body 12 is propped against by a displacement measuring sleeve body, and initially, a displacement transmission mechanism 6 is in contact with the connecting block;
the other end of the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part 8 and the jack action part 9 are sequentially and coaxially connected, the extension steel strand 11 sequentially penetrates through the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part 8 and the jack action part 9, the jack action part 9 clamps the extension steel strand 11, and the jack action part 9 is driven by the jack static part 8 to apply a reverse-pulling driving force which is gradually increased from the inner part of the prestressed concrete to the outer part;
as shown in figure 6 of the drawings,
the displacement recorder is connected with the displacement sensor 7 and records a displacement value, and the displacement value is regarded as a deformation quantity of the prestressed steel strand 2;
the counter-pulling driving force recorder is connected with the bridge type pressure sensor and records a pressure value, and the pressure value is regarded as a counter-pulling driving force corresponding to the deformation amount of the prestressed steel strand 2;
the reverse-pulling driving force controller controls the jack static part 8 to apply a gradually increased reverse-pulling driving force from the inner part of the prestressed concrete to the outer part to the jack action part 9;
and the reverse pulling driving force controller controls the reverse pulling driving force to stop increasing the reverse pulling driving force when the reverse pulling driving force exceeds a set driving force safety limit value or the displacement exceeds a set displacement safety limit value.
Wherein the static part 8 of the jack comprises an oil pump machine and a jack pressure body.
The reverse-pulling driving force controller, the reverse-pulling driving force recorder and the displacement recorder may be the same execution body or different execution bodies.
Further, in the above-mentioned case,
the connecting block includes: stud 13, left sleeve 14, left clamping piece 15, right sleeve 16, right clamping piece 17, left sleeve 14 is interior to be equipped with left clamping piece 15, right sleeve 16 and is interior to be equipped with right clamping piece 17, and the prestressing force steel strand wires 2 that are located the ground tackle clamping piece 4 outside insert in left clamping piece 15, the one end of extension steel strand wires 11 inserts in right clamping piece 17, and left sleeve 14, right sleeve 16 are inserted respectively to stud 13 both ends.
Some factors that need to be considered in the above embodiments are:
the concrete process of carrying out grouting defect detection on the grouting pore channel where the prestressed steel strand 2 is located by adopting grouting defect detection equipment comprises the following steps: and (3) distributing points along the measuring lines on the top plate or the bottom plate corresponding to the grouting channel where the prestressed steel strands 2 are located, and performing data acquisition on the measuring lines by adopting an impact echo method and analyzing the grouting defects of the grouting channel.
The target deformation quantity delta L is set and increased along with the increase of the length L of the free section of the stress steel strand 2 exposed out of the grouting body 10.
The target deformation quantity Delta L is adjusted to be 1mm-2 mm.
In addition, the purpose of detecting the effective prestress under the steel strand anchor after grouting is as follows: and comparing the prestress with the effective prestress design value under the current detection working condition and the anchor, thereby evaluating whether the prestress of the prestress steel strand reaches the standard or not. The design value of the effective prestress under the anchor can be obtained by calculation according to specification files such as JTG 3362 and the like.
The invention connects the cut prestressed steel strands into a whole through the connector and completely covers the connecting part (connector) of the steel strands through the connector outer sealing body, thereby providing a counter-pulling force applied by counter-pulling equipment.
The diameter of the connector is 49mm, the length is 194mm, the annealing hardness is not more than 235HB, and the whole connector can bear the tensile force not less than 200 KN.
The length of the displacement measurement tool is larger than 200mm, the diameter of the displacement measurement tool is larger than 49mm, the annealing hardness of the stainless steel material is not larger than 235HB, and the whole displacement measurement tool can bear pressure of not smaller than 250 KN.
The oil pump and the jack in the counter-pulling force equipment can apply the maximum tension force of 250 KN.
The method of the invention needs two sets of equipment to be matched for completion, the first set of equipment is grouting defect detection equipment, the grouting defect detection equipment is equipment for detecting defects by using an echo method, and the equipment is the prior art and is not described herein again. The equipment can obtain the defects in the prestressed concrete, and after the target defects are screened out, the length of the corresponding prestressed steel strand section is calibrated according to the length of the target defects. The second set of equipment is the counter-pulling equipment, which is described in detail in the present invention, and which can be either the existing counter-pulling equipment as described in the background art, or the counter-pulling equipment formed by adding a connector to the existing counter-pulling equipment.
The foregoing is only a preferred embodiment of the present invention, and the present invention is not limited thereto in any way, and any simple modification, equivalent replacement and improvement made to the above embodiment within the spirit and principle of the present invention still fall within the protection scope of the present invention.
Claims (10)
1. The method for detecting the effective prestress under the steel strand anchor after grouting is characterized in that the method acts on prestressed concrete (1), the prestressed concrete (1) comprises a concrete body, a grouting pore channel positioned in the concrete body, prestressed steel strands (2) positioned in the grouting pore channel, anchors (3) fixed on two sides of the concrete body, and two ends of each prestressed steel strand (2) are clamped by anchor clamping pieces (4) in the anchors (3); the method is applied to grouting of the grouting hole where the prestressed steel strand (2) is located; the method comprises the following steps:
s1, after grouting a grouting body (10) formed in a grouting channel where a prestressed steel strand (2) is located, detecting the length dimension L of a free section of the prestressed steel strand (2) exposed out of the grouting body (10);
s2, grouting a grouting body (10) formed by grouting a grouting channel where the prestressed steel strand (2) is located, applying a reverse pulling driving force which is gradually increased from the inside of prestressed concrete to the outside to the prestressed steel strand (2), recording the deformation quantity of the prestressed steel strand (2) and the corresponding reverse pulling driving force, extracting a target deformation quantity delta L after the deformation quantity is subjected to primary jump and a corresponding reverse pulling driving force F, and determining that the deformation quantity is subjected to primary jump as controllable elastic deformation jump of a free section of the prestressed steel strand (2) exposed out of the grouting body (10);
and S3, calculating an elastic deformation correction force Fx according to the length dimension L and the target deformation quantity delta L, wherein Fx is delta L/L E A, calculating an effective prestress Fy under the steel strand anchor after grouting according to the elastic deformation correction force Fx and a reverse pulling driving force F, Fy is F-Fx, A is the cross-sectional area of the stress steel strand (2), and E is the elastic modulus of the prestress steel strand (2).
2. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 1, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the specific process for detecting the length dimension L of the free section of the prestressed steel strand (2) exposed out of the grouting body (10) comprises the following steps:
after grouting a grouting hole where the prestressed steel strand (2) is located to form grouting body (10), grouting defect detection is carried out on the grouting hole where the prestressed steel strand (2) is located by grouting defect detection equipment, grouting defects adjacent to an anchorage device (3) are screened from the grouting defects to be inherent grouting defects (18) of a post-tensioned prestressed concrete process, the length dimension L1 of the inherent grouting defects (18) of the post-tensioned prestressed concrete process is obtained, and the length dimension L1 is regarded as a first free section of the prestressed steel strand (2);
measuring the length dimension L2 of an anchor clamping piece (4) positioned in the anchor, and regarding the length dimension L2 as a second free section of the prestressed steel strand (2);
measuring the length dimension L3 of the prestressed steel strand (2) positioned outside the anchor clamping piece (4), and regarding the length dimension L3 as a third free section of the prestressed steel strand (2);
the length dimension L of the free section of the prestressed steel strand (2) exposed out of the grouting body (10) is as follows: l1 or L1+ L2 or L1+ L2+ L3.
3. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 1, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the specific process of applying the gradually increased reverse-pulling driving force from the inside of the prestressed concrete to the outside to the prestressed steel strand (2) is as follows:
and a reverse-pulling device is adopted to connect the part of the prestressed steel strand (2) exposed out of the anchor clamping piece (4) and apply a reverse-pulling driving force which is gradually increased from the inner part of the prestressed concrete to the outer part to the prestressed steel strand (2).
4. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 3, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the reverse pulling equipment is used for controlling the reverse pulling driving force to exceed a set driving force safety limit value or stopping increasing the reverse pulling driving force when the displacement exceeds a set displacement safety limit value.
5. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 3, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the counter-pulling equipment comprises: the device comprises a displacement measuring tool (5), a bridge type pressure sensor, a driving jack, a displacement recorder, a reverse-pulling driving force recorder and a reverse-pulling driving force controller;
the displacement measurement tool (5) comprises a displacement measurement sleeve body, a displacement transmission mechanism (6) arranged at the eccentric position of the displacement measurement sleeve body and a displacement sensor (7) for sensing the displacement transmission mechanism (6);
the driving jack comprises a jack static part (8) and a jack action part (9);
the prestressed steel strand (2) positioned outside the anchor clamping piece (4) penetrates through the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part (8) and the jack action part (9);
one end of the displacement measuring sleeve body is pressed against the outer side surface of the anchorage device, and the displacement transmission mechanism (6) is initially contacted with the anchorage device clamping piece (4); the other end of the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part (8) and the jack action part (9) are sequentially and coaxially connected, the jack action part (9) clamps the prestressed steel strand (2), and the jack action part (9) is driven by the jack static part (8) to apply a counter-pulling driving force which is gradually increased from the inside of the prestressed concrete to the outside;
the displacement recorder is connected with the displacement sensor (7) and records a displacement value, and the displacement value is regarded as a deformation quantity of the prestressed steel strand (2);
the counter-pulling driving force recorder is connected with the bridge type pressure sensor and records a pressure value, and the pressure value is regarded as a counter-pulling driving force corresponding to the deformation amount of the prestressed steel strand (2);
the reverse-pulling driving force controller controls the jack static part (8) to apply a gradually increased reverse-pulling driving force from the inner part of the prestressed concrete to the outer part to the jack action part (9);
and the reverse pulling driving force controller controls the reverse pulling driving force to stop increasing the reverse pulling driving force when the reverse pulling driving force exceeds a set driving force safety limit value or the displacement exceeds a set displacement safety limit value.
6. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 3, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the counter-pulling equipment comprises: the device comprises an extension steel strand (11), a connector, a displacement measuring tool (5), a bridge type pressure sensor, a driving jack, a displacement recorder, a counter-pulling driving force recorder and a counter-pulling driving force controller;
the displacement measurement tool (5) comprises a displacement measurement sleeve body, a displacement transmission mechanism (6) arranged at the eccentric position of the displacement measurement sleeve body and a displacement sensor (7) for sensing the displacement transmission mechanism (6);
the driving jack comprises a jack static part (8) and a jack action part (9);
the connector comprises a connector outer sealing body (12) and a connecting block, wherein a prestressed steel strand (2) positioned outside an anchor clamping piece (4) is inserted into the connecting block, one end of an extension steel strand (11) is inserted into the connecting block, one end of the connector outer sealing body (12) is pressed against the outer side surface of the anchor, the connecting block is arranged in the connector outer sealing body (12) and can move, the other end of the connector outer sealing body (12) is pressed against by a displacement measuring sleeve body, and initially, a displacement transmission mechanism (6) is in contact with the connecting block;
the other end of the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part (8) and the jack action part (9) are sequentially and coaxially connected, the extension steel strand (11) sequentially penetrates through the displacement measuring sleeve body, the bridge type pressure sensor, the jack static part (8) and the jack action part (9), the jack action part (9) clamps the extension steel strand (11), and the jack action part (9) applies a reverse-pulling driving force which is gradually increased from the inner part of the prestressed concrete to the outside under the driving of the jack static part (8);
the displacement recorder is connected with the displacement sensor (7) and records a displacement value, and the displacement value is regarded as a deformation quantity of the prestressed steel strand (2);
the counter-pulling driving force recorder is connected with the bridge type pressure sensor and records a pressure value, and the pressure value is regarded as a counter-pulling driving force corresponding to the deformation amount of the prestressed steel strand (2);
the reverse-pulling driving force controller controls the jack static part (8) to apply a gradually increased reverse-pulling driving force from the inner part of the prestressed concrete to the outer part to the jack action part (9);
and the reverse pulling driving force controller controls the reverse pulling driving force to stop increasing the reverse pulling driving force when the reverse pulling driving force exceeds a set driving force safety limit value or the displacement exceeds a set displacement safety limit value.
7. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 6, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the connecting block includes: stud (13), left sleeve (14), left clamping piece (15), right sleeve (16), right clamping piece (17), establish left clamping piece (15) in left sleeve (14), establish right clamping piece (17) in right sleeve (16), be located outside prestressing force steel strand wires (2) of ground tackle clamping piece (4) and insert left clamping piece (15), the one end of extension steel strand wires (11) inserts right clamping piece (17), left sleeve (14), right sleeve (16) are inserted respectively at stud (13) both ends.
8. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 2, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the concrete process of carrying out grouting defect detection on the grouting pore channel where the prestressed steel strand (2) is located by adopting grouting defect detection equipment comprises the following steps: and (3) distributing points along the measuring lines on the top plate or the bottom plate corresponding to the grouting hole where the prestressed steel strand (2) is located, and performing data acquisition on the measuring lines by adopting an impact echo method and analyzing the grouting defects of the grouting hole.
9. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 1, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the target deformation quantity delta L is set and increased along with the increase of the length L of the free section of the stress steel strand (2) exposed out of the grouting body (10).
10. The method for detecting the effective prestress under the steel strand anchor after grouting according to claim 1, wherein the effective prestress under the steel strand anchor is detected by the following steps:
the target deformation quantity Delta L is adjusted to be 1mm-2 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210496899.5A CN114878048A (en) | 2022-05-09 | 2022-05-09 | Method for detecting effective prestress under steel strand anchor after grouting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210496899.5A CN114878048A (en) | 2022-05-09 | 2022-05-09 | Method for detecting effective prestress under steel strand anchor after grouting |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114878048A true CN114878048A (en) | 2022-08-09 |
Family
ID=82673917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210496899.5A Pending CN114878048A (en) | 2022-05-09 | 2022-05-09 | Method for detecting effective prestress under steel strand anchor after grouting |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114878048A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117110207A (en) * | 2023-06-27 | 2023-11-24 | 安徽通利预应力科技有限公司 | Online elemental analysis device for steel strand production |
-
2022
- 2022-05-09 CN CN202210496899.5A patent/CN114878048A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117110207A (en) * | 2023-06-27 | 2023-11-24 | 安徽通利预应力科技有限公司 | Online elemental analysis device for steel strand production |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105651684B (en) | The detection method of post-tensioned concrete structure friction loss and anchorage loss | |
| JP5071805B2 (en) | Re-tension method and load measurement method of existing anchor, and head part | |
| RU2515412C2 (en) | Method and method of uniform jacking of strands | |
| CN111811715A (en) | Connecting device for detecting end part of prestress value and detection method | |
| CN111811716A (en) | Single-hole clamping piece anchorage device capable of measuring force for prestress and device and method for measuring force of prestress value | |
| JP3397142B2 (en) | How to measure anchor tension | |
| CN114878048A (en) | Method for detecting effective prestress under steel strand anchor after grouting | |
| CN110593489A (en) | Low-retraction prestressed tendon anchorage system and use method | |
| CN217403661U (en) | Connector and counter-pulling device for detecting effective prestress under steel strand anchor after grouting | |
| CN112146980B (en) | System and method for judging initial tension force and pressure stabilizing time of prestressed steel strand | |
| JP5142029B2 (en) | Anchor function status confirmation device | |
| CN110761563B (en) | Steel strand prestress applying device and method and prestress steel structure stair | |
| JP4316283B2 (en) | Tensile anchorage structure and tendon stress measurement method | |
| US6880412B1 (en) | Device and method for testing the tension in stressed cables of concrete structure | |
| JP2006337058A (en) | Load measuring method for existing anchor and re-tensing method for existing anchor | |
| JP2001133392A (en) | Measuring method of fixing force for anchor material | |
| CN114428015B (en) | Device and method for testing prestress loss of carbon fiber reinforced composite bar | |
| CN217006730U (en) | Anti bearing capacity test system that slides of cable and cable clamp built-up member buckle | |
| CN212621225U (en) | Single-hole clamping piece anchorage device capable of measuring force for prestress and prestress value measuring device | |
| CN114720105A (en) | Test method and device for testing bearing capacity of bridge hoop | |
| JP4912673B2 (en) | Tensile force detection method for tendons | |
| CN210513651U (en) | Beam-end anti-friction resistance effect testing arrangement | |
| WO2006018656A1 (en) | Improved anchorage head assembly | |
| Forbes et al. | A new look at cable bolt and D-bolt support under axial load | |
| JP2002267593A (en) | Method for testing anchor body, method for adjusting, and supporting table and load cell used in these methods |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |