Shear test device and shear test method in in-situ soil body pore

Abstract

The invention discloses a shear test device and a shear test method in an in-situ soil body pore. The test device is lowered to a test point by utilizing a drilling machine to bore, normal stress is provided by applying air pressure to facilitate the expansion of an airbag so as to drive a shear barrel to be expanded, a shear cutter on the periphery of the shear barrel can be inserted into a soil body so as to solidify the soil body, a steel rod is driven by applying hydraulic pressure through a gear to lift so as to drive the shear cutter to cut the soil body, the soil body is cut and destructed, and finally a shear index of the soil body can be calculated according to a coulombs law. The test method comprises the steps of boring, assembling the test device, lowering the device, solidifying, cutting and processing data. The invention also provides a shear test device in the in-situ soil body pore. According to the technical scheme, the strength index of the soil body can be determined under a natural stress state. The shear test device and the shear test method have advantages of low price, simplicity in operation, short test time and strong applicability.

Description

technical field [0001] The invention relates to a soil in-situ test device and a test method, in particular to a soil in-situ shear test device in a hole and an in-situ test method for the shear strength of the soil. Background technique [0002] The shear strength of soil refers to the ultimate strength of soil against shear failure, including cohesion C and internal friction angle It is one of the important mechanical properties of soil, and it is also an important parameter for calculating the stability of slopes such as cuttings, channels, embankments, and earth dams, as well as the earth pressure of supporting buildings. At present, the shear strength of soil is mainly obtained through laboratory tests and in-situ tests. Indoor tests include soil direct shear tests, triaxial shear tests, etc. However, due to the size limitation of indoor tests, the representativeness is poor, and the empirical criteria are artificial, which leads to large dispersion of soil shear stre...

AI Technical Summary

Problems solved by technology

At present, the in-situ shear tests of soil mainly include large-scale direct shear tests and cross-plate shear tests, etc., but large-scale direct shear tests have the disadvantages of expensive tests, long periods, and complicated operations, while cross-plate shear tests can only obtain viscoelasticity. Juli C, the internal friction angle cannot be obtained And it cannot be used for soft clay containing sand, gravel, shells and other components. When there is a silt interlayer, the measurement results are often too large

For this reason, some geotechnical workers have developed different in-situ shear test equipment and methods for rock and soil, such as the Rock Borehole Shear Test, which is widely used abroad. This equipment has the advantages of simple operation, The advantage of high repeatability, but this equipment is only suitable for soft to medium hardness rock mass, and it is not suitable for soil whose shear strength is less than dozens of times of rock mass, and the test accuracy is also greatly reduced

For the in-situ shear strength test of soil, the in-situ soil borehole shear instrument is widely used, but this test equipment can only obtain the cohesion C and internal friction angle of the soil The stress-strain relationship curve that characterizes the strength characteristics of the soil cannot be obtained, and the method of loading the shear stress is to manually shake the gear, which will lead to the need to apply a large artificial mechanical force when the strength of the test soil is high, which is time-consuming and labor-intensive. Applicable Sex is not strong

For this reason, the invention patent soil in-situ shear and static load tester (Application No.: 201310697634.2) provides an in-situ shear test equipment, but the equipment uses a disc formed by a pendulum supported by a support rod to test the soil body shearing, this mechanical control method cannot ensure that the pendulum blocks are evenly opened, and there may be local shearing of the surrounding soil, and reliable test data cannot be obtained. Broken rock blocks are likely to jam the support rod, causing the test to fail

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