Estimation of the pore water pressure and the settlement of saturated clay subjected to undrained multi-directional cyclic shear by using hypecbolic function in combination with the “curve-fitting” method

Abstract

In this research, saturated-normally consolidated samples of kaolinite clay were tested under undrained uni-directional and multi-directional cyclic simple shears with various shear strain amplitude (g), cyclic shear direction and consolidation pressure (s_v0). It is indicated from experiment results that cyclic shear direction and shear strain amplitude have important effect on the pore water pressure accumulation during undrained cyclic shear and the recompression characteristics after cyclic shear, meanwhile the effect of consolidation pressure on these properties, at least in the range from 49 kPa to 98 kPa, is negligible. The pore water pressure induced by multi-directional cyclic shear can be estimated by using hyperbolic function of shear strain amplitude and the number of cycles in combination with the “curve-fitting” technique. However, the obtained results for the case of multi-directional cyclic shear is not so good as those for the uni-directional one, especially in the range of g = 0.3% ~ 0.8%. On the other hand, the conventional estimation method of post-cyclic settlement can be used in combination with different compression indices for predicting the settlement of saturated clay layer subjected to undrained multi-directional cyclic shear.

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