Study On Effcets Of Physical Properties On Mechanical Behaviors Of Gravel Soil

Gravel soil generally consists of coarse and fine grained soil composition, which is the coarse grain content higher than fine grain and a commonly seen type of soil in the engineering practice. Because of the complexity in the composition of the gravel soil and of the differences in the sizes of soil particles, the compressive and shear properties of the gravel soil is particularly affected by their physical characteristics especially under the effect of evident particle grading which to some extent determines the mechanical properties of the gravel soil. Based on the gravel soil slope project in the bridge site of Dadu River in Ya’an-Kangding highway in Sichuan province, through large-scale direct shear and compression tests and particle flow numerical simulation of PFC, this paper makes analyze on how changes in the gravel for soil moisture content and graduation affect the shear and compression characteristics, the main research work and results are as follows:1) The original samples were taken from the gravel soil in the Dadu bridge of alongside the bridge in the Ya’an-Kangding highway, which were to prepare 6 kinds of gravel soil samples with different graduation, and 2 of the 6 kinds of samples was selected and divided into 5 different groups of formulated water content. Thus a total of 14 different test soil samples were prepared for large direct shear and compression tests.2) With the change of the sample of coarse gravel content, the shear strength parameters and friction angle within soil samples changed, while the cohesion in P=58.84% of the critical point showing the minimum value. With the change in water content, the specimen has an effect on friction angle, shear strength is another indicator of cohesion by moisture effect obviously.3) With the increasing of the coarse grain content, the void ratio and compression modulus of gravel soils showed a decreasing trend, indicating that the content of the coarse gravel soil affected less in its coefficient compression and the compression factor of each sample were less than 0.1MPa-1. With the increase of water content, the high compressibility of the sample gradually became lower.4) We make the direct shear test and compression test process simulation Through the PFC2D particle flow simulation software, analyzing the shear pressure variation rule of shear plane in different positions during the shearing process and the compression pressure variation rule in different positions during the compression process. And we conclude the difference and similarities in the experimental rules through macroscopic view and the discipline of the results of the numerical simulation.This thesis makes certain reference values for the construction of gravel land area in southwest China, and for geological hazard prevention and treatment.