Shear Strength Behavior Of Over-consolidation Clay In Ring Shear Tests

Landslide is one of the main geological disasters. Many landslides occur high speed and long distance sliding failure, and the sliding distance often amount to more than ten meters, even upper hundred meters. Damage and loss that this landslide brings about are also the maximal. Therefore, it's necessary to carry out detailed experiments on this high speed and long distance landslide disaster.Since conventional direct shear apparatus and triaxial apparatus can't satisfy this long shear displacement by whose strain range, as being used to study soil mechanics in large shear distance, ring shear apparatus has distinctive design and test functions, and already expand to the research field involving soil shear failure process. At present, ring shear apparatus play an important role in research on strain softening aspect.This paper is based on looking up and collecting datum broadly, and use home and abroad researches for reference. Researches were conducted on representative Changchun Q₂ silty clay by employing ring shear apparatus in Jilin University. Tests reached a few meaningful conclusions, and it will provide certain reference to further researches. The main work is following as:(1) Looking back to the history and development of researches on aspects of softening, residual strength and impact of cyclic load over clay shear strength. Be aimed at actual projects, research significance of this paper were set forth.(2) Detailed researches were carried out on history, fundamental composition and main functions of ring shear apparatus, and detailed expounding on material and sample preparation was also carried out(3) Look up experiment method about measuring clay residual strength broadly, and carried out analysis and comparison on various experiment methods. Meanwhile, the major factors affecting clay residual strength were summed up.(4) Tests reach results of peak strength, residual strength and softening characters of over-consolidation clays influenced by over-consolidation ratio, normal stress and shearing speed. Meanwhile, the variation of residual strength before and after applying cyclic load was reached. This paper also got the results of soil strain softening and residual strength under cyclic load influenced by frequency and vibrating direction.