GB817295A - Apparatus and method for determining in situ the soil permeability and the water pressure - Google Patents

Abstract

817,295. Testing physical properties of soil. STICHTING WATERBOUWKUNDIG LABORATORIUM. Aug. 10, 1956, No. 24591/56. Class 106 (2). Apparatus to determine in situ the permeability of water-bearing soil comprises a tube 1 to be driven into the soil, having a closure 8 at its upper part and fine openings 2 in its lower part, a water-pressure gauge 5 connected with the interior of the tube 1, means 12 for filling the tube 1 with water, and an elastic bellows or the like 14. In operation, the tube 1 is driven into the soil to a desired depth, and a tap 10 closed. The tube is then filled with water and a cap 8 fitted to the upper end. Water will flow through the openings 2, which are covered by a filter, either into or out of the tube 1, until equilibrium is reached between the pressure of water in the tube 1 and the pressure of water in the surrounding soil. This pressure can then be read directly on an electric measuring instrument 7 connected to the gauge 5 which is of the capacitative type. To determine the permeability of the soil, a tap 11 is opened and vessel 14 filled with water through the funnel 12. The vessel 14 is then compressed, so that water in the funnel 12 rises, and the tap 11 is closed. The bellows are then released and the tap 10 opened. The vessel 14 will try to regain its initial volume thus forming a degree of vacuum in the vessel 14 and tubes 4, 1. Thus water is sucked up from the soil through the holes 2, and the rate of change of pressure of water in the tube, which may be recorded, gives an indication of the permeability of the soil. Another embodiment provides a plurality of bellows each of which may be connected to the tube 1 according to the size and flexibility required for best results with the type of soil under test. A further embodiment uses a liquid which does not mix with water (such as mercury) in a U-tube, to provide the partial vacuum required.