Ring Shear Study On Large Shear Mechanic Properties Between Heterogeneous Soils

In recent years, with the rapid development of economy and the demand of human society and engineering construction, a large number of landslide disasters occurred in China. The occurrence of these landslides are actually a sliding shear process that occurs on a certain sliding path along the sliding path. In the process of shear failure, the interfacial shear effect may change the physical and mechanical properties of the original rock and soil. Although many researchers and institutions at home and abroad have carried out a series of detailed studies on the landslide hazard, the study on the mechanical properties of the large shear in different rock and soil media is not deep enough. Therefore, it is necessary to take a certain technical means, for the soil of the landslide in a detailed experimental study.Laboratory soil test is the most effective method to study the shear mechanics properties of soil. Because of the limit of the structure and the structure of the conventional direct shear apparatus and the three axis compression apparatus, the experimental conditions for the large displacement and shear of soil can not be satisfied. As the ring shear apparatus has a unique ring shear design. Such as in the process of shear the shear surface area can be maintained, and the specimen can be carried out under continuous displacement conditions. Therefore, it can meet the requirements and conditions of the mechanical properties of soil under the condition of large shear displacement. Because of its unique design structure and test function, the ring shear apparatus became a kind of soil testing equipment which is suitable for studying the mechanical properties of soil under the condition of large shear displacement. With the development of science and technology, the ring shear apparatus has been applied to many research fields, such as strain softening, residual shear strength, mechanical characteristics of soil and structure, and the cause analysis of geological hazard..This paper draws on the experience and results of the research on the mechanical properties of the large shear in different soil, and a large number of documents were collected to collect all kinds of relevant information. A series of ring shear tests of the Dalian coastal silty clay, standard sand and the soil of two kinds of soil are carried out by using the large high speed ring shear apparatus of Jilin University. The works of this paper as follows:(1) This paper reviewed the domestic and foreign research results about the landslide hazard, and analyzed the actual landslide occurrence and movement mechanism, and put forward the practical significance of this research.(2) This paper studied three methods of measuring the residual strength. And elaborated the structure principle and applicable condition of the direct shear apparatus and triaxial compression apparatus and structure principle and application condition of ring shear apparatus.(3) The paper descripts the large high speed ring shear apparatus in details.And with the large high shear apparatus, this paper studied on the peak strength,residual strength and strain softening of Dalian coastal silty clay and standard sand at different normal stress and shear velocity. And then this article studied on the large shear mechanical properties of heterogeneous soil which made by coastal silty clay of Dalian and standard sand.(4) Through multi group experiments,this paper obtained the relationship curve of shear displacement shear stress curve of Dalian coastal silty clay and standard sand at different normal stress and shear velocity. While, this discourse fitted the relationship curve between peak shear strength and normal stress of silty clay,and then analyzed the formation mechanism of the test results all the above.(5) Based on the ring shear test results of two single soil samples, the experimental study on the shear test of the heterogeneous soil was carried out in details.Then the paper analyed the shear mechanical properties of the three samples.At the last the paper obtained the variation law of shear strength of the heterogeneous soil.In this paper, the research methods and results could provide a theoretical basis and reference value for the future research on the mechanical properties of the soil.