Study Of Strength Model Of K₀ Consolidated Saturated Clay Under Cyclic Loading

It is the key to study the cyclic strength of saturated clay subjected to combined work loads and cyclic loads caused by environment under undrained conditions for the bearing capacity and stability analysis of foundations. Therefore it is meaningful to study the variation of undrained cyclic strength of k0 consolidated clay experienced combined static and cyclic loads. The variation of undrained cyclic strength is researched from the view of material strength theory in this paper. The relationship of cyclic strength among different stress conditions is also considered. The k0 consolidated process must be simulated in triaxial cell due to studying the development of undrained static and cyclic strength of k0 consolidated saturated clay by traxial tests. In order to solve this problem, the k0 factor could be firstly measured by radial displacement transducer .And then the cross section of the specimen could be kept to initial value through loading gradually basing on the k0 factor in k0 consolidated process.Further, the development of undrained static strength for k0 consolidated saturated clay is researched by triaxial compression tests under three confining pressures and triaxial extension tests under two confining pressures. Undrained static strength data of triaxial compression, extension and direct simple tests for undisturbed k0 consolidated Drammen clay are analyzed in addition. A conclusion could be obtained that the relationship of undrained static strength of triaxial compression; triaxial extension and direct simple test can be expressed by Mohr-Coulomb strength criterion based on researched results.Finally, the cyclic strength's development rule and deformation failure model of k0 consolidated saturated clay subjected to different combination of static and cyclic loading under reversal and non-reversal stress conditions are studied by using cyclic triaxial tests. The cyclic strength and deformation failure model data of triaxial and direct simple tests for undisturbed k0 consolidated Drammen clay are also analyzed. Following conclusions are obtained based on researched results. The estimations of the cyclic strength of triaxial extension and direct simple test have some errors compared with the real strength using cyclic Mohr-Coulomb strength parameters determined by cyclic triaxial compression tests. But the error becomes relative little at the larger number of cyclic to failure. It can be thought approximatively that the relationship of undrained cyclic strength of triaxial compression; triaxial extension and direct simple test could be expressed by Mohr-Coulomb strength criterion. The deformation failure models of cyclic triaxial compression tests, extension tests and cyclic direct simple tests are the same without reversal stress for a specific initial octahedral shear stress ratio. If these tests'elements experience reversal stress for the same initial octahedral shear stress ratio and the same number of cyclic to failure, the deformation failure models are almost the same from the angle of qualitative analysis. However, they make a difference from the angle of quantitative analysis.