Coarse-grained soil direct shear test method for simulating in-situ test by laboratory test

Abstract

The invention discloses a coarse-grained soil direct shear test method for simulating an in-situ test by a laboratory test. A giant-grained group which contains a giant-grained soil granular composition is compressed into a grain group (d is greater than 40mm and less than or equal to 60mm) to obtain a sample preparation granular composition; according to the sample preparation granular composition and moisture contents and compactness appointed by the test, the coarse-grained soil specified by a regulation is directly subjected to a shear test to obtain a measurement value; through a graphical method, shear strength cohesion and frictional coefficients are solved; then, two groups of new direct shear intensity parameters are obtained independently through an optimal slope fitting method and an optimal intercept fitting method; and when a rolling body is in different normal stress ranges, a parameter which is calculated by a new intensity parameter and has a low shearing stress numerical value is taken as the direct shearing intensity parameter of the rolling body. By use of the method, the weight percentage content of each grain group (d is less than or equal to 40mm) is maintained to be constant, the practical filling state of a coarse-grained soil filling body is simulated to a maximum degree, a saturation condition direct shear test can be carried out, experience and test measurement value can be both given a consideration, and the obtained parameter exhibits better representativeness and scientificity.

Description

technical field [0001] The invention relates to the field of water conservancy engineering detection, in particular to a direct shear test method for coarse-grained soil using indoor tests to simulate in-situ tests. The indoor coarse-grained soil test simulates the in-situ direct shear test of the soil containing giant grains. Background technique [0002] At present, in-situ tests or direct shear tests of coarse-grained soils are generally used to obtain the direct shear strength parameters of roller compacted fillings containing giant-grained soils, that is, friction coefficient and cohesion. The in-situ test not only has a long period and high cost, but also is difficult to achieve a saturated state. Indoor coarse-grained soil direct shear test, the test method stipulated in the water conservancy regulations is: according to the actual gradation curve of soil containing giant grains, according to the mass percentage content of each grain group, the total amount of each g...

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Problems solved by technology

[0003] The above rules and methods have obvious defects: First, in the giant-grained soil, the lithology of the coarse gravel (60mm≥d>20mm) in the giant-grained group and the coarse-grained group is relatively consistent, while that of the fine gravel (20mm≥d>2mm) The lithology is different, and the specific gravity of the fine gravel group is increased by the procedure method, and the lithology and content of the fine gravel group are the main factors affecting the direct shear strength of the coarse-grained soil; second, the least square method only relies on the test value to calculate the shear strength parameters, while the graphic method is more focused on experience and has more subjective factors

Therefore, the direct shear test of coarse-grained soil specified in the regulations is difficult to simulate the field in-situ test

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