Instrment for testing geotextile permeability and silting property

Abstract

The invention refers to an apparatus to test permeability coefficient and silting character of the geotextiles. It sets inner and outer tubes in penetrating container, forming flow-measuring region in the inner tube and outboard balance region between two tubes, and left and right water exits connected with the flow-measuring and outboard balance regions, respectively. It only uses seepage-measuring results in the middle part to calculate the permeability coefficient, overcoming the border effect, simulates practical force state of the geotextiles, and also can calculate the magnitude of seepage by determining the outboard and middle seepage at the same time.

Description

technical field [0001] The invention relates to a testing instrument, in particular to an instrument for testing the permeability coefficient and blocking characteristics of geotextiles. Background technique [0002] At present, due to the strong tensile strength of geotextiles, it can effectively prevent seepage deformation in the seepage and overflow areas. Especially, the pore diameter and pore distance of needle-punched non-woven geotextiles can be set more accurately, and the permeability coefficient can be relatively high. It is widely used in different projects as reverse filter material and water-proof material due to its good control. However, in specific engineering applications, needle-punched non-woven geotextiles need to withstand the pressure of the overlying rock and soil, and their thickness will change greatly, as will the pore diameter and permeability coefficient. The permeability coefficient under pressure is measured to adapt to engineering construction...

AI Technical Summary

Problems solved by technology

[0003] Before the present invention is made, the instrument of measuring the permeability coefficient of above-mentioned fabric and silt-up characteristic is as the instrument that permeameter combines with consolidation meter, but this instrument surveys the permeability coefficient measurement process to fabric, and fabric can occur in vertical seepage process Lateral seepage, and the ratio of lateral seepage to vertical seepage will increase with the increase of normal stress, up to 3% to 5%, which seriously affects the measurement accuracy. At the same time, in the measurement process, in order to reduce If the amount of lateral leakage is large, the upper and lower test cylinders must be tightened with greater pressure, which in turn causes the thickness of the clamped parts around the fabric to become thinner, and a bulge is formed on both sides of the middle part of the sample. The degree of bulge depends on the The increase of the number of fabric layers and the tightening pressure increases, so that the force of the fabric is uneven when the lower normal stress acts, and the streamline is not a parallel straight line, resulting in low reliability of the test measurement

Another example is another improved penetrometer, which keeps the sample fabric basically horizontal through the action of the rubber gasket under a small pressure, and then conducts a vertical permeation test, but this is theoretically feasible, but in practice, Due to the error of circular geotextile sample preparation, concentrated leakage is likely to occur at the contact part between the inner wall of the permeameter and the fabric, which makes the measured permeability coefficient too large, inaccurate and unreliable, and the instrument cannot apply vertical pressure and cannot simulate The actual stress state of the fabric at work

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