The Experiment Study On Response Mechanism Of Vertical Compressive Properties Of Red Clay To Limit Condition

Soil is a discontinuous,inhomogeneous and anisotropic body,which is formed under the interaction of various complex conditions.For engineering construction,the bearing capacity of soil is the most common and important parameter.In nature,the rock mass buried in the deep surface of the earth is in the state of compression,which is in the state of confined compression.In addition,in the nature and engineering construction but also the distribution in the rock and soil under pressure in various side,reference number and relative position of the free surface side limit compression state is divided into the unconfined compression condition;the single side limit compression condition;condition of the adjacent side limit compression;compression limit the condition on the opposite side;the three side limit compression condition(four);the complete 6 side limit compression condition.However,the experimental conditions can only simulate the strength and deformation characteristics of rock and soil mass under the condition of unconfined compression,and can not be applied to the experimental study of rock and soil mass under other confining conditions.Based on this,this paper studies the test and the disaster mechanism of red soil slope in response to the National Natural Science Fund Project "extreme rainfall effect"(project number: 41462011)as the basis,to Jiangxi city in Nanchang Province,the typical Quaternary red clay as the research object,through processing equipment,laboratory tests and theoretical analysis techniques,design and development a set of adjustable side limit state confined compression auxiliary device,combined with hydraulic servo press,respectively different sides of different basic physical and mechanical properties,under the condition of limited vertical compression test.Research on the part of the unconfined conditions the mechanical response characteristics,and with the construction of calculation model of advanced numerical simulation experiment,in order from the vertical stress and displacement and shear strain rate evolution comprehensively and analysis of the differences represented by rock and soil conditions in the compression process of different side,through indoor unconfined compression test and FLAC3 D numerical simulation combining and comparative analysis,which can accurately analyze the rock mass deformation and strength characteristics in various complicated conditions.The study will provide a useful reference for further enriching the exploitation and utilization of underground space in geotechnical engineering,and provide a theoretical basis for the development of the partial confined compression test equipment.The main work and research results are as follows:(1)Collected a large number of red clay in the construction of roadbed in Jiangxi Province,Nanchang City Economic Development Zone,to test basic physical properties of the interior of red clay,red clay so as to obtain the particle size distribution of composition,plastic limit WP,liquid limit,WL cohesion c and internal friction angle of basic physics mechanical parameters.(2)According to the different initial water content,different moisture content and different dry red clay density to carry out six kinds of unconfined compression tests under vertical load,and the single,adjacent surface,three surface and the opposite side limit state of the stress-strain relationship of development can be divided into four periods: close and the pressure of the elastic deformation stage;nonlinear hardening stage;the softening stage;the stage of steady flow.There are three stages in the stress strain relationship under the four lateral confined condition,the linear elastic stage and the nonlinear low speed strengthening stage.With the increase of initial water content,and the single,adjacent surface,opposite,three face and four side limit under the peak strength of red clay increase nonlinearly;increase the peak strength of the whole and surrounded by red clay on the side with the initial water content decreased;the residual strength increases with the initial water content.When the initial water content is constant,the relationship between the peak strength of red clay and the limit of each side is that the single side is limited to the limit of the "side of the side" and the "three side".With the increase of initial water content,the peak strain increased;no,one side,adjacent surface,three surface and four side limit state of elastic modulus decreases with increasing initial moisture content,and the relationship between the state and the initial moisture content on the opposite side is increased first and then decreased.(3)With the increase of the final moisture content,the peak strength of the red clay was increased and then decreased.When the final moisture content is constant,the relationship between the residual strength of the red clay and the lateral confining condition is as follows: the one side is limited to one side and the other is the opposite side.The peak strength,residual strength,peak strain and compression modulus of red clay increased with the increase of dry density.(4)To the interior of red clay unconfined compression test of FLAC3 D numerical simulation test of vertical,according to actual situation of red clay specimens and test conditions,using a cube model,simulate the cube in adjacent surface,and one side,opposite the three side and four side limit stress condition,comparison through the analysis of numerical simulation test and laboratory test results,numerical simulation and laboratory test results are in good agreement,to prove the feasibility of the numerical simulation method.Based on this,we can use the numerical simulation method to solve the problem when some special test conditions are difficult to be realized.