CN117071621A - Basin-type curtain construction method for pit-in-pit strong permeable layer - Google Patents
Basin-type curtain construction method for pit-in-pit strong permeable layer Download PDFInfo
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- CN117071621A CN117071621A CN202311091393.7A CN202311091393A CN117071621A CN 117071621 A CN117071621 A CN 117071621A CN 202311091393 A CN202311091393 A CN 202311091393A CN 117071621 A CN117071621 A CN 117071621A
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
- E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
- E02D5/46—Concrete or concrete-like piles cast in position ; Apparatus for making same making in situ by forcing bonding agents into gravel fillings or the soil
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- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Structural Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Bulkheads Adapted To Foundation Construction (AREA)
Abstract
The application relates to the technical field of building foundation construction, solves the problem of lower construction efficiency and quality of a pit-in-pit water stop structure, and discloses a pit-in-pit basin-type curtain construction method with a strong permeable layer, which comprises the following construction steps: preparing construction, measuring and lofting, jet grouting pile body, pile body maintenance and pit excavation. Measuring and marking the position of each pile body after leveling the bottom surface in the foundation pit, wherein the top elevation of the waterproof pile is lower than the top elevation of the curtain pile, the waterproof pile and the curtain pile are sprayed out in a rotating mode according to the designed pile position and elevation, cement slurry is not sprayed out in a rotating mode to form an excavation portion above the top elevation position of the waterproof pile, the waterproof pile and the curtain pile form a basin-shaped waterproof curtain with grooves, then a pit in the excavation portion is excavated, construction resistance is reduced, in the excavation process, the waterproof curtain can prevent groundwater from penetrating into the pit in the pit, pumping is not needed to be carried out on the bottom of the pit in the pit, construction efficiency is improved, and construction quality is also improved.
Description
Technical Field
The application relates to the technical field of building foundation construction, in particular to a basin-type curtain construction method for a pit-in-pit strong permeable layer.
Background
After the basement large foundation pit is excavated to the designed pit bottom elevation, the underground pit is further excavated downwards at the positions of the elevator pit and the water collecting well to form local small pits, namely pit-in-pit. The pit in the pit is positioned in a deeper layer of the foundation pit and is easy to encounter strong permeable layers such as sand, eggs, gravel and the like, so that the water stopping structure with good waterproof performance is needed for the pit in the pit so as to prevent leakage of underground water.
A layer of stirring piles or jet grouting piles are arranged on the periphery of a pit to serve as waterproof curtains, dewatering wells are arranged around the pit or in the middle of the pit, water in the pit is pumped cleanly through a water pump, the water pump is left in the well when the dewatering wells are plugged, and the water pump is pumped by the water pump when water seeps into the pit again.
However, this construction method has poor water stopping effect, even if the water level rises upward more than the water level is pumped; furthermore, even can take out water under the hole bottom elevation position, when the waterproof bed course is beaten to the hole bottom, if take place the condition that has a power failure or the pump burns out, can lead to the water level to rise again, the water pressure wears the bed course top, just needs to chisel the bed course, the construction again, wastes time and energy, still increases construction cost.
Disclosure of Invention
In order to improve the defects of low construction efficiency and quality of a pit-in-pit water stop structure, the application provides a basin-type curtain construction method of a pit-in-pit strong permeable layer.
The application provides a basin-type curtain construction method of a pit-in-pit strong permeable layer, which adopts the following technical scheme:
the pit-in-pit strong permeable layer basin-type curtain construction method comprises the following construction steps:
and (3) measuring and lofting: measuring pile positions of a plurality of curtain piles and water-proof piles according to the bottom surface of a foundation pit, and marking, wherein the pile positions of the curtain piles are surrounded to form a closed ring, and the pile position arrays of the water-proof piles are arranged in the pile positions of the curtain piles;
jet grouting pile body: the top elevation of the waterproof pile is lower than the top elevation of the curtain pile, the curtain pile and the waterproof pile are ejected in a rotating mode according to the marked pile position and the designed elevation, the adjacent curtain pile and the waterproof pile are meshed with each other, and an excavation portion is formed above the top elevation of the waterproof pile;
digging pit: digging out a pit in the pit according to the design of the excavation part marked on the water-proof pile.
By adopting the technical scheme, the position of each pile body is measured and marked after the bottom surface in the foundation pit is leveled, firstly, a water-proof pile and a curtain pile are sprayed out in a rotary mode according to the designed pile position and elevation, slurry is not sprayed out in a rotary mode above the elevation position of the top of the water-proof pile to form an excavation part, the excavation part is equivalent to a hollow hole of the rotary spraying pile body, and the water-proof pile and the curtain pile form a basin-shaped with a groove; because the pressure of jet grouting pile is great, so the marine insulating pile of jet grouting probably has some to return thick liquid, returns thick liquid and can upwards fill the sky hole, still can fall into some rubble sandy soil in the sky hole, then excavate out the hole in the position of excavation portion, in the recess of "basin form", reduced the construction resistance. In the process of digging the pit in the pit, the waterproof pile and the curtain pile can form a waterproof curtain surrounding the periphery and the bottom of the pit in the pit, the waterproof curtain can prevent underground water from penetrating into the pit in the pit, and a water pump is not needed to pump water at the bottom of the pit in the process of digging, so that the construction efficiency is improved, and the construction quality is also improved; in addition, because the compressive strength of the water-stop curtain sprayed out by rotation is high, the situation that the water-stop curtain is cracked by groundwater with overlarge water pressure can be avoided, and the construction stability is ensured.
Optionally, in the step of jet grouting the pile body, the curtain pile is jet grouting first, a reinforcement is inserted into the middle of the curtain pile along the length direction of the curtain pile, and then the waterproof pile is jet grouting.
Through adopting above-mentioned technical scheme, spout the curtain stake in the outside soon earlier, spout inside water proof stake soon again, can keep apart the inside strong permeable layer with foundation ditch bottom of whole basin-type curtain earlier to reduce the likelihood of infiltration when spouting water proof stake soon afterwards, improve efficiency of construction, and preferably offer the construction from the water proof stake adjacent with the curtain stake, just as much as possible earlier with the pile body interlock of spouting soon when can making inside water proof stake jet soon, thereby can improve the structural stability of water proof curtain, make the interlock inseparabler.
Optionally, the top elevation of the curtain pile is lower than the bottom surface of the foundation pit.
Through adopting above-mentioned technical scheme, the top elevation of curtain stake is less than the bottom surface of foundation ditch and also forms "hole" of spouting the pile body soon, and the hole can reduce the thick liquid that returns in the curtain stake and emit the possibility that flows to the foundation ditch surface, reduces the work load of constructor clearance, can also utilize to return thick liquid to fill the hole, further save material.
Optionally, the bottom elevation of the waterproof pile is more than 1 meter away from the top elevation.
Through adopting above-mentioned technical scheme, the height that water proof stake spouted soon is 1 meter at least, can play better stagnant water effect, and guarantees the compressive capacity of water proof stake, reduces the likelihood that high-pressure groundwater in the strong permeable layer will separate water proof stake top and split.
Optionally, an opening edge of the pit in the pit is spaced from the curtain pile.
By adopting the technical scheme, the distance between the edge of the upper opening of the pit in the pit cannot exceed the inner edge of the curtain pile, so that the curtain pile can be prevented from being excavated in the process of excavating the edge of the pit in the pit, the water stopping effect of the curtain pile can be ensured, and the reinforcement can be inserted into the curtain pile.
Optionally, an intersection point exists between the opening edge of the pit in the pit and the water isolation pile positioned at the outermost ring.
Through adopting above-mentioned technical scheme, in the hole the opening edge just in time is located on the water proof stake of outer lane, can make full use of jet grouting stake's area, reduce the waste of material, further reduce construction cost, resources are saved.
Optionally, the marking method in the measuring and lofting step is as follows: and after the counter bore is pricked at the measured pile position, filling the counter bore with marking powder.
Through adopting above-mentioned technical scheme, can prick the counter bore that the diameter is less with the stake position with the bar rod after measuring the stake position, then landfill marked powder in the counter bore, compare in direct dusting marking, can improve the accuracy of marking, reduce the offset in stake hole center when follow-up drilling, guarantee the compactness of interlock between the adjacent jet grouting pile body.
Optionally, the pile body is maintained for 2-3 days before the pit and groove excavation step.
Through adopting above-mentioned technical scheme, revolve spun water proof stake and curtain stake need avoid sunshine to penetrate directly and drench with the rain, make spouting the stake body soon solidify, and the maintenance time is preferably 2 to 3 days alright make the stake body reach the solidification state that can play the stagnant water effect and can not be too hard, be convenient for follow-up open pit in the pit.
Optionally, the cement slurry is doped with a curing agent, wherein the curing agent comprises a first surfactant with a molecular weight of 130-800 and a second surfactant with a molecular weight of 1000-10000, and the mass ratio of the first surfactant to the second surfactant is 1:0.2-0.5.
By adopting the technical scheme, the first surfactant with the molecular weight of 130-800 is a low molecular weight surfactant, so that the precipitation and layering of cement slurry can be reduced, and the stability and controllability of a reaction system in the cement slurry can be enhanced; the second surfactant with the molecular weight of 1000-10000 is a high molecular weight surfactant, so that the cohesive force of cement slurry can be improved, and the solidification speed can be accelerated; the content of the first surfactant is more, so that the overall uniformity of the rotary spraying pile body can be improved, the diameters of the pile bodies are consistent, the biting stability among the pile bodies is improved, and the water stopping effect is ensured.
Optionally, the mixing amount of cement in the pile body sprayed by the rotary spraying machine is set to be 25% of the mass of the pile body.
Through adopting above-mentioned technical scheme, the mixing amount of cement in the jet grouting pile is the proportion with the soil reinforcement, and 25% cement output can solidify soil and improve pile body intensity very fast, reduces the fracture after curtain stake and the water proof stake are pressed, warp the possibility, guarantees the stagnant water effect.
In summary, the present application includes at least one of the following beneficial effects:
1. the bottom surface in the foundation pit is sprayed with a water-proof pile and a curtain pile in a rotating mode, the rotating spraying height of the water-proof pile is lower than that of the curtain pile, a basin-shaped waterproof curtain is formed, then a pit is dug out above the rotating spraying position of the water-proof pile, the waterproof curtain can prevent groundwater from penetrating into the pit in the process of digging the pit, a water pump is not needed to pump water to the bottom of the pit in the process of digging, construction efficiency is improved, and construction quality is also improved;
2. because the compressive strength of the water-proof piles and the curtain piles sprayed out is high, the situation that the water-proof curtain is cracked by groundwater with excessive water pressure can be avoided, and the construction stability is ensured.
Drawings
FIG. 1 is a cross-sectional view of a well-in-well strongly permeable layer basin-type curtain in accordance with an embodiment of the present application;
FIG. 2 is a top view of a basin-type curtain of a pit-in-pit water-permeable layer in a pit according to an embodiment of the present application;
FIG. 3 is a cross-sectional view taken along the direction A-A in FIG. 1;
FIG. 4 is a process flow diagram of basin-type curtain construction of a pit-in-pit strongly permeable layer in a pit according to an embodiment of the present application;
FIG. 5 is a flow chart of the internal jet sequence in the step of jet grouting the pile body in accordance with the first embodiment of the present application;
FIG. 6 is a cross-sectional view of a pit-in-pit strongly permeable layer basin-type curtain in accordance with a second embodiment of the present application;
FIG. 7 is a top view of a pit-in-pit highly permeable layer basin-type curtain in accordance with a second embodiment of the present application.
Reference numerals illustrate: 1. a foundation pit; 2. pit in pit; 3. a waterproof curtain; 31. curtain piles; 32. a water-proof pile; 4. an excavation part; 5. a hollow hole; 6. returning slurry; 7. and (3) a reinforcement.
Detailed Description
The application is described in further detail below with reference to fig. 1-7.
Embodiment one:
referring to fig. 1 to 3, an embodiment of the present application discloses a method for constructing a basin-type curtain of a pit-in-pit strong permeable layer in a pit, wherein the basin-type curtain of the pit-in-pit 2 strong permeable layer comprises a plurality of waterproof piles 32 arranged in an array and a plurality of curtain piles 31 surrounding the waterproof piles 32. Referring to fig. 4, the construction method includes the steps of:
s1, preparation of construction: including site leveling and building of sewage disposal systems.
(1) Leveling the field: after the foundation pit 1 is excavated, firstly, removing the barriers on the ground in the foundation pit 1, then reasonably arranging the positions of construction machinery, a conveying pipeline and a power line, and carrying out site leveling compaction by an excavator to ensure that the site is level and three-way and one-way.
(2) Constructing a sewage disposal system: because the depth of the pit 2 in the pit such as the elevator pit and the water collecting well is generally 1-6 m, the rotary jet grouting pile construction method is preferably adopted for the water isolation pile 32 and the curtain pile 31 in the embodiment, and because the rotary jet grouting pile for the pit 2 is short, partial slurry return 6 can be generated in the construction process, a sedimentation tank (the size is determined according to the slurry return amount) can be piled up by soil near the rotary jet grouting pile, and the slurry return 6 of the rotary jet grouting pile can be introduced into the sedimentation tank.
S2, measuring and lofting: paying off according to the design construction drawing, and positioning the pile.
Corresponding to the positions of the pit 2 in the pit, such as the elevator pit, the water collecting pit and the like, which need to be dug, the control points of all curtain piles 31 and waterproof piles 32 are measured on the bottom surface of the foundation pit 1 by using a total station according to the design, stone burying is carried out firstly, then, after the test line is qualified again and the inspection is carried out again, pile positions are laid on the spot by using a steel rule and a test line, marks are made, and then, bamboo sticks are nailed tightly after marking, and each pile position corresponds to one bamboo stick. Specifically, the marking method comprises the following steps: the measured pile position is pricked with a counter bore with smaller diameter by adopting a steel bar rod, the depth of the counter bore is preferably 20-30 cm, the counter bore is filled with marking powder, compared with the process of directly powdering the surface of the foundation pit 1 to mark, the marking accuracy can be improved, the offset of the center of the pile hole in the subsequent drilling process is reduced, and the center offset of the pile hole is ensured to be less than 50 mm; the marking powder is lime, and the lime can be combined with soil to achieve good marking effect. It should be noted that, the pile positions of the curtain piles 31 are enclosed to form a closed ring, which may be a circular ring or a square ring, preferably a square ring with four equal sides, preferably, the curtain piles 31 may be arranged in two circles to improve the compressive strength, and meanwhile, the two circles of curtain piles 31 can achieve the specified water-stop effect, and the pile positions of the waterproof piles 32 are arranged in the pile positions of the curtain piles 31 in a rectangular array.
S3, a jet grouting pile body, wherein in other embodiments, the water isolation pile 32 and the curtain pile 31 can be stirring piles; in the present embodiment, the waterproof pile 32 and the curtain pile 31 are preferably jet grouting piles using a jet grouting machine, and the jet grouting piles are high-pressure jet grouting methods, and have high water stopping capability and high compressive strength. Specifically, the jet grouting pile body comprises the following steps: the rotary spraying machine is in place, rotary spraying drilling, rotary spraying lifting and rotary spraying machine shifting.
It should be noted that, the design elevation of the top of the curtain pile 31 is lower than the bottom surface of the foundation pit 1, and the effective elevation of the top of the curtain pile 31 is preferably lower than the bottom surface of the foundation pit 1 by more than 0.3 meter; the design elevation at the top of the waterproof pile 32 is lower than the design elevation at the top of the curtain pile 31, and the bottom elevation of the waterproof pile 32 is more than 1 meter away from the top elevation, so that the bottom elevation of the curtain pile 31 and the bottom elevation of the waterproof pile 32 can be consistent, a good water stopping effect can be achieved, the compression resistance of the waterproof pile 32 is ensured, and the possibility that high-pressure underground water in a strong water permeable layer cracks the waterproof pile 32 is reduced.
The rotary spraying machine comprises a drill rod with a drill bit at the bottom, wherein a nozzle is arranged on the drill bit, in the embodiment, the triple pipe rotary spraying machine is preferably adopted for carrying out triple pipe rotary spraying, namely, two nozzles enable high-pressure water and compressed air to be sprayed transversely at the same time, soil in a foundation pit 1 is cut, broken soil is removed from the ground surface by means of the lifting force of the air, meanwhile, the other nozzle sprays cement slurry to the soil which is cut and stirred, cement slurry and soil are mixed to achieve the reinforcing purpose, the water stopping effect is further improved, the reinforcing diameter can reach 0.6-1 m, and in the embodiment, the reinforcing diameter is enabled to be 0.8 m by controlling the pressure, namely, the diameters of a water isolation pile 32 and a curtain pile 31 are 0.8 m. Furthermore, the construction is preferably carried out by adopting a long spiral jet grouting stirring pile, and the strength of the jet grouting pile body is further improved by adopting a jet grouting stirring mode.
(1) And (3) positioning a rotary spraying machine: leveling and centering the rotary spraying machine, adjusting the verticality of the rotary spraying machine, and carrying out duplex check by adopting two theodolites on the front and the side, so as to ensure that the drill rod is consistent with the pile position in the step S2, the deviation is within 10mm, and the error of the verticality of the drilling hole is less than 0.3%; and verifying the length of the drill rod, marking a depth line beside the drilling tower by using red paint according to the bottom elevation lengths of the waterproof piles 32 and the curtain piles 31, and ensuring that the hole bottom elevation of the pile hole meets the design depth. Before drilling, an air compressor and a grouting pump are adjusted to ensure that the equipment operates normally.
(2) Rotary jet drilling: before the construction of the rotary spraying machine, the test spraying should be performed on the ground first, after the mechanical test operation of the rotary spraying machine is normal, the drill bit starts to drill corresponding to the pile position, and the drilling depth is the bottom elevation of the waterproof pile 32 and the curtain pile 31. The drilling rod section number is recorded in detail in the drilling process, so that the accuracy of the drilling depth is ensured. In the drilling process, in order to prevent the muddy sand from blocking the nozzle, water or cement slurry is sprayed while drilling is performed, and meanwhile, the pressure is controlled. If any theodolite finds deviation in the drilling process, constructors need to be fed back in time to adjust in real time, so that verticality is ensured.
(3) Lifting by jet grouting: after the drill bit drills to the elevation of the bottom of the pile body, the drill bit is then rotated from bottom to top, and even if the triple pipe is used for spraying high-pressure water, compressed air and cement slurry. When spraying, the preset spraying pressure is reached, and then the rotary spraying drill rod is gradually lifted after the slurry spraying is started; in order to ensure the quality of the bottom end of the pile body, the nozzle should rotate in situ for about 10 seconds at the designed depth, and the jet grouting time of the drill rod should be properly increased within the range of 1 meter at the bottom of the pile. The rotation and lifting of the drill rod should be continuously performed without interruption, and if the drilling machine fails, the lifting and rotation of the drill rod should be stopped to prevent pile breakage and immediately overhauling to remove the failure. And stopping rotary spraying when the nozzles are lifted to the top elevation positions of the curtain piles 31 and the waterproof piles 32, and continuously lifting the drill bit upwards to be separated from the pile holes.
It should be noted that, because the jet grouting is stopped by the nozzle, the water-proof pile 32 is formed with the excavation portion 4 above the top elevation, the excavation portion 4 is equivalent to the "hole 5" of the jet grouting pile body, and the top elevation of the curtain pile 31 is lower than the bottom surface of the foundation pit 1, the hole 5 can also be formed, the possibility that the return slurry 6 in the jet grouting pile flows out to the surface of the foundation pit 1 can be reduced, the workload of constructors for cleaning is reduced, the hole 5 can be filled with the return slurry 6, and the material is further saved.
(4) Shifting a rotary spraying machine: after the drill bit is separated from the pile hole, the pipeline, grouting pipe and other equipment of the rotary spraying machine are washed. And then the rotary spraying machine is shifted to the next adjacent pile position, and the two steps of rotary spraying drilling and rotary spraying lifting are repeated, so that the rotary spraying adjacent curtain piles 31 and the waterproof piles 32 are mutually meshed and are arranged in a quincuncial full red, and the higher curtain piles 31 and the lower waterproof piles 32 form a water-stop curtain 3 in a basin shape. It should be noted that, referring to fig. 5, the curtain pile 31 of the outer ring needs to be sprayed soon first, so that the inside of the whole basin-type curtain is isolated from the strong permeable layer at the bottom of the foundation pit 1, then the waterproof pile 32 is sprayed soon, the possibility of water seepage can be reduced, the construction efficiency is improved, and when the waterproof pile 32 is sprayed soon, the construction is preferably carried out from the waterproof pile 32 adjacent to the curtain pile 31, so that when the waterproof pile 32 in the inside is sprayed soon, as much pile body is meshed with the sprayed pile body as soon as possible, thereby improving the structural stability of the waterproof curtain 3 and enabling the meshing to be tighter. It should be noted that the waterproof piles 32 adjacent to the curtain piles 31 are constructed after being offset downwards by 0.3 m, namely the elevation position of the top of the waterproof pile 32 at the outermost ring is always equal to the elevation position of the curtain piles 31, so that the engagement between the waterproof piles 32 and the curtain piles 31 can be ensured; the positions of other water-proof piles 32 are unchanged, and the jumping is implemented, so that the hole strings are prevented.
In addition, the cement slurry sprayed by the rotary spraying machine is doped with a curing agent, so that the strength is improved, the compactness is improved, and the water stopping reliability is improved. The cement may be p.o42.5, p.s.a32.5, p.s.b32.5, p.c32.5, etc., preferably p.o42.5; the curing agent comprises a first surfactant with a molecular weight of 130-800 and a second surfactant with a molecular weight of 1000-10000, wherein the mass ratio of the first surfactant to the second surfactant is 1:0.2-0.5. The first surfactant is selected from one or more of butyl naphthalene sulfonate, dioctyl sodium succinate sulfonate, glyceryl monostearate and alkyl ether carboxylate, and the second surfactant is selected from one or more of alkyl polyether PO-EO copolymer, fatty alcohol polyoxyethylene ether ammonium sulfate, fatty alcohol polyoxyethylene ether sodium sulfate and fatty alcohol polyoxyethylene ether. The first surfactant is a low molecular weight surfactant, so that the precipitation and layering of cement slurry can be reduced, and the stability and controllability of a reaction system in the cement slurry can be enhanced; the second surfactant is a high molecular weight surfactant, so that the cohesive force of cement slurry can be improved, and the solidification speed can be increased; the content of the first surfactant is more, so that the overall uniformity of the rotary spraying pile body can be improved, the diameters of the pile bodies are consistent, the biting stability among the pile bodies is improved, and the water stopping effect is ensured. Further, the mixing amount of cement in the pile body of the existing rotary spraying machine is generally set to be 15% -18% of the mass of the pile body, the mixing amount of cement in the rotary spraying pile is the proportion of the cement to the reinforced soil, in the embodiment, the mixing amount of cement is set to be 25%, the cement yield of 25% can quickly solidify the soil and improve the strength of the pile body, the possibility of fracture and deformation of the curtain pile 31 and the waterproof pile 32 after being pressed is reduced, and the water stopping effect is ensured.
And S4, maintaining the pile body to enable the jet grouting pile body to reach the specified hardness.
The rotary spraying water-proof piles 32 and curtain piles 31 need to avoid direct sunlight and rain, the rotary spraying piles are solidified, the maintenance time is preferably 2 to 3 days, the piles can reach a solidification state which can play a water stopping effect and are not too hard, and meanwhile, the surface of the foundation pit 1 is pumped in an open row, so that the pit 2 in the pit can be conveniently opened in the follow-up pit.
S5, pit excavation: the pit 2 is dug out of the excavation portion 4 marked on the waterproof pile 32 according to the design.
So the rotary sprayed waterproof pile 32 may have part of the slurry returning liquid 6, the slurry returning liquid 6 can fill the excavation part 4 (the hollow hole 5) upwards, part of the broken stone sand can fall into the excavation part 4, then the pit in pit 2 is excavated in the groove of the excavation part 4, namely the basin-shaped waterproof curtain 3, so that the construction resistance is reduced, and the waste of rotary spraying materials is reduced. In the process of digging the pit 2, the waterproof curtain 3 can prevent underground water from penetrating into the pit 2, and a water pump is not needed to pump water at the bottom of the pit 2 in the process of digging, so that the construction efficiency is improved, and the construction quality is also improved; in addition, because the compressive strength of the water-stop curtain 3 sprayed out by rotation is large, the situation that the water-stop curtain 3 is cracked by groundwater with overlarge water pressure can be avoided, and the construction stability is ensured. It should be noted that, the elevation of the bottom of the pit 2 in the pit is greater than the elevation of the top of the water-proof pile 32 by more than 0.3 meter, so that the damage of the rotary spraying part of the water-proof pile 32 by the excavator is avoided, the water-stop effect is ensured, and the pit 2 in the pit is excavated to the bottom without manually excavating the water-proof pile 32 so as to avoid the damage, thereby further improving the construction efficiency. The distance between the opening edge of the pit 2 in the pit and the curtain pile 31 exists, so that the curtain pile 31 can be prevented from being excavated in the process of excavating the edge of the pit 2 in the pit, the water stopping effect of the curtain pile 31 can be guaranteed, further, the intersection point exists between the opening edge of the pit 2 in the pit and the water-proof pile 32 positioned on the outermost ring, the distance between the opening edge of the pit 2 in the pit cannot exceed the inner edge of the curtain pile 31, the area of the jet grouting pile can be fully utilized, the waste of materials is reduced, the construction cost is further reduced, and the resources are saved. If water is leaked from an individual leakage point in the excavation process, target point leakage stoppage can be carried out by adopting double-slurry materials including cement slurry, water glass and other additives.
In the embodiment, the inner wall of the pit 2 in the pit is vertically dug to form a vertical inner wall, so that different building requirements can be met. Referring to fig. 4, after the curtain pile 31 is spun-sprayed, the reinforcement 7 is inserted into the middle of the curtain pile 31 along the length direction of the curtain pile 31 to form a support pile, and the reinforcement 7 is inserted into the curtain pile 31 adjacent to the waterproof pile 32, and then the inner waterproof pile 32 is spun-sprayed. The reinforcement 7 can be I-steel, H-steel, precast piles or piles made of other materials, and is preferably I-steel; the length of the reinforcement 7 is consistent with the rotary spraying height of the curtain piles 31, the I-steel arrangement form can be in a close-insert type, a two-jump-one-insert type or a one-jump-one-insert type, and preferably, the close-insert type is adopted, namely, the reinforcement 7 is inserted into each curtain pile 31, and the reinforcement 7 can further play a supporting role on the pits 2 in the pits, so that the building quality is improved.
Embodiment two:
referring to fig. 6 and 7, the embodiment of the application discloses a basin-type curtain construction method of a strong permeable layer in a pit, which is different from the first embodiment in that the side wall of the pit 2 in the pit is dug to be provided with a flaring inclined towards the upper pit opening direction, and the pit 2 in the pit has a structure with a large upper opening and a small lower opening.
Because the inclined inner wall can make the structure of the pit 2 more stable, in the step S3 of the first embodiment, after the curtain pile 31 on the outer side is sprayed, the waterproof pile 32 can be sprayed directly without inserting a support plate into the curtain pile 31, thereby further reducing the construction cost and improving the construction efficiency. Since the water-blocking pile 32 is provided with the hollow hole 5 at a position above the elevation of the bottom of the pit 2, and the inner side wall of the pit 2 is inclined upward, the hollow hole 5 at the side wall of the pit 2 is finally filled with cement slurry.
The above embodiments are not intended to limit the scope of the present application, so: all equivalent changes in structure, shape and principle of the application should be covered in the scope of protection of the application.
Claims (10)
1. The pit-in-pit strong permeable layer basin-type curtain construction method is characterized by comprising the following construction steps:
and (3) measuring and lofting: measuring pile positions of a plurality of curtain piles (31) and water-proof piles (32) according to the bottom surface of a foundation pit (1), and marking, wherein the pile positions of the curtain piles (31) are surrounded to form a closed ring, and the pile position arrays of the water-proof piles (32) are arranged in the pile positions of the curtain piles (31);
jet grouting pile body: the top elevation of the waterproof pile (32) is lower than the top elevation of the curtain pile (31), the curtain pile (31) and the waterproof pile (32) are ejected in a rotating mode according to the marked pile position and the design elevation, the adjacent curtain pile (31) and the waterproof pile (32) are meshed with each other, and an excavation part (4) is formed above the top elevation of the waterproof pile (32);
digging pit: digging out the pit (2) in the pit according to the design of the digging part (4) marked on the water-proof pile (32).
2. The method for constructing the basin-type curtain of the pit-in-pit strong permeable layer according to claim 1, wherein in the step of jet grouting the pile body, the curtain pile (31) is jet grouting first, a reinforcement (7) is inserted into the middle part of the curtain pile (31) along the length direction of the curtain pile (31), and then the water-proof pile (32) is jet grouting.
3. The method for constructing the basin-type curtain of the pit-in-pit strong permeable layer according to claim 1, wherein the top elevation of the curtain pile (31) is lower than the bottom surface of the foundation pit (1).
4. The method of constructing a basin-type curtain of a pit-in-pit strong permeable layer according to claim 1, wherein the bottom elevation of the marine pile (32) is 1 meter or more from the top elevation.
5. The method of constructing a basin-type curtain of a pit-in-pit strong permeable layer according to claim 1, characterized in that the opening edge of the pit-in-pit (2) is located at a distance from the curtain pile (31).
6. The method for constructing the basin-type curtain of the pit-in-pit strong permeable layer according to claim 5, wherein an intersection point exists between the opening edge of the pit-in-pit (2) and the water-proof pile (32) positioned at the outermost ring.
7. The method for constructing the basin-type curtain of the pit-in-pit strong permeable layer according to claim 1, wherein the marking method in the measuring and lofting step is as follows: and after the counter bore is pricked at the measured pile position, filling the counter bore with marking powder.
8. The method for constructing a basin-type curtain of a strong permeable layer in a pit according to claim 1, wherein the pile body is maintained for 2-3 days before the step of digging the pit.
9. The method for constructing a basin-type curtain of a pit-in-pit strong permeable layer according to claim 1, wherein a curing agent is mixed in the cement slurry, the curing agent comprises a first surfactant with a molecular weight of 130-800 and a second surfactant with a molecular weight of 1000-10000, and the mass ratio of the first surfactant to the second surfactant is 1:0.2-0.5.
10. The construction method of the basin-type curtain of the strong permeable layer in the pit, according to claim 9, wherein the mixing amount of cement in the pile body sprayed by the rotary spraying machine is set to be 25% of the mass of the pile body.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311091393.7A CN117071621A (en) | 2023-08-28 | 2023-08-28 | Basin-type curtain construction method for pit-in-pit strong permeable layer |
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| CN202311091393.7A CN117071621A (en) | 2023-08-28 | 2023-08-28 | Basin-type curtain construction method for pit-in-pit strong permeable layer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117266207A (en) * | 2023-11-23 | 2023-12-22 | 北京建工集团有限责任公司 | Low-cost precipitation system of foundation pit small in scale and difficult to cause sedimentation |
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- 2023-08-28 CN CN202311091393.7A patent/CN117071621A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117266207A (en) * | 2023-11-23 | 2023-12-22 | 北京建工集团有限责任公司 | Low-cost precipitation system of foundation pit small in scale and difficult to cause sedimentation |
| CN117266207B (en) * | 2023-11-23 | 2024-02-09 | 北京建工集团有限责任公司 | Foundation pit dewatering system difficult to cause sedimentation |
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