Study On The Interface Shear Behavior Between Unsaturated High Liquid Limit Clay And Geotextiles Considering The Variation Of Suction

As a high liquid, high void ratio and strong regional specific soil, the high liquid limit clay is commonly widespread in southern China. In order to reduce the impact on the environment, from the point of view of the environmental protection and sustainable development, people often take advantage of the high liquid limit clay or its slightly improved as the high filling. In order to improve the strength and deformation characteristics of the high filling, often pave geosynthetics (geogrid, geotextile, etc.)in the high filling. Affected by the climates, the suction change in the reinforced body, it affects the reinforced soil interface characteristic. So this thesis mainly analyses the interface characteristics between unsaturated high liquid limit clay-geotextiles. This thesis consists of four parts as follows:Firstly, this part presents briefly the background of research, the objectives and specific issues to be investigated, and the organization of the thesis.Secondly, introduces the concepts of unsaturated soil and the research status of the unsaturated interfaces. Experimental technique and testing apparatus is illustrated.Then, use the ZFY-1A type of unsaturated soil strain control direct shear apparatus, control suction of unsaturated high liquid limit clay-geotextiles interface, carry on the direct shear test and analysis:1. Unsaturated high liquid limit clay-geotextiles interface shear test, study interface shear characteristics under different suctions. The experimental results show that the influence of suction and net stress on shear behavior of interface is significant. Shear strength of interface increases with matric suction and net stress. Greater interfacial cohesive force and internal friction angle is found at higher suction, but smaller δb is found at the same time.2. Suction cycles of high liquid limit clay-geotextiles interface shear test, applied the suction cycles approach to simulate the function of wet and dry cycles and applied different number of suction cycles to carry out the interface shear test. The suction cycles have influence on the hardening-softening behavior of clay-geotextiles interface. When the same net normal stress, with the increase number of suction cycles, the interface strength variation presented first increased and then decreased the change rule. Experience three dry-wet circulation, interface shear strength is lower than zero dry-wet circulation. On the whole, interface strength is decreasing.3. Based on the test results, the stability analysis of reinforced retaining wall is studied. To explore retaining wall of security is influenced by the suction change.Finally, conclusions and recommendations:In this part, the main findings and conclusions obtained from the present study are presented, followed by the recommendations for future studies in the topic area.