A Direct Shear Test Method for Coarse-grained Soil Using Indoor Test to Simulate In-situ Test

Abstract

The invention discloses a direct shear test method of coarse-grained soil by indoor test simulating in-situ test, compressing the gradation of the giant-grained group containing giant-grained soil into the 60mm≥d>40mm grain group, and obtaining the sample preparation grade According to the sample preparation gradation and the moisture content and compaction degree specified in the test, the measured value is obtained by the direct shear test of the coarse-grained soil specified in the regulations, and the shear strength cohesion and friction coefficient are calculated by the graphical method, and then the slope is determined respectively Two sets of new direct shear strength parameters are obtained by the fitting method and the optimal intercept fitting method. When the rolled body is in different normal stress ranges, the one with the lower shear stress value calculated by the new strength parameters is regarded as the rolling body. Body direct shear strength parameters. The present invention maintains the mass percentage content of each particle group with d≤40mm unchanged, simulates the actual filling state of the coarse-grained soil filling body to the greatest extent, can carry out the direct shear test in the saturated state, and takes into account experience and test values, and the obtained parameters More representative and scientific.

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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