Study On The Deformation, Strength Characteristics Of The Soil-rock Mixture And The Interaction Mechanism Between Soil And Gravel

Soil-rock mixture is widely distributed in nature, different from the general soil, which is composed of high strength rock and fine grained soil with weak strength. Many natural disasters, such as landslide and debris flow are related with soil-rock mixture because of its poor stability and complex structure. In this paper, triaxial shear tests with CT scan were conducted on the soil-rock mixture with different stone content. The influence of stone content on the triaxial shear strength and deformation characteristics of soil-rock mixture were analyzed. The deformation and failure process of soil-rock mixture were scanned using CT technology. The soil-rock mixture section image information was obtained by applying image binarization technology and the gravel boundary was recognized in order to extract cloud data of gravel surface point, separate the gravel and soil, and quantitatively analyze the gravel movement within the soil-rock mixture and the interaction between soil and gravel.The main research and results are as follows:(1) The current researches on soil-rock mixture were summarized.(2) Triaxial tests were conducted on the soil-rock mixture with different gravel content. It’s concluded that the cohesion of the samples decreases and the internal friction angle increases with the increasing of gravel content;(3) The shear strength of soil-rock mixture increases along with confining pressure. The stress-strain curve is obviously nonlinear. At low confining pressure, with the increasing of stone content, the peak strength decreases first and then increases; at high confining pressure, the peak strength of samples increased. (4) The displacement of gravels in the upper part of triaxial samples is largest and mainly vertical. In the middle part, gravels moves laterally and vertically and the displacement is relatively small. In the lower part, gravel’s displacement is very small, and rock move along the shear zone.(5) Gravels will rotate during the triaxial experiment. The rotation angles are related to the gravel size, shape, orientation, location, stress and interaction between gravels. Rotation angle is larger while gravel is smaller, more flat, more close to the sample boundary, and the stress is more highly concentrated and the constraints between gravels are less;(6) In the triaxial shearing process, the extrusion between the gravel and soil, soil disturbance and cracking phenomena can be observed.