RESEARCH ON SHEAR DEFORMATION CHARACTERISTICS OF SOIL-ROCK MIXTURES UNDER DIFFERENT STONE CONTENTS

Soil-rock mixtures are widely distributed in the Three Gorges Reservoir area. The mechanical properties and deformation response of the soil-rock mixtures under external action have an important influence on the initiation or reactivation of landslide on the reservoir bank. The soil-rock mixture of typical landslide in the Three Gorges Reservoir area is selected for sampling,and the large scale direct shear tests on soil-rock mixture is carried out in laboratory. The deformation characteristics of soil-rock mixture under different rock contents are studied based on the method of drilling,wire inserting and sand filling. The results show that the stone content has an obvious control effect on the strength and deformation characteristics of the soil-rock mixture. When the content of stone is less than 20%,the effect of block stone on the sample is small,and the fine-grained soil is the dominant factor. The shear deformation of fine-grained soil is characterized by staggered shear deformation,and the strength depends on the strength of fine particles,and the specimen shows strain hardening characteristics. With the increase of stone content(20% ~80%),the block stone begins to contact and gradually forms the skeleton structure. In addition,because of interlocking of fine-grained soil,the dilatancy of samples are enhanced. The shearing process is characterized by the gnawing type shear deformation between the mixture,and the strength is affected by the joint action of the block stone and the fine particles. At the same time,the samples show strain softening characteristics gradually. When the stone content is more than 80%,the block stone in the sample is dominant,the structure effect of the sample is reduced,and the strength and deformation performance are weakened.