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| Effect of angle between directions of initial shear stress and cyclic load on softening properties of soft clay |
| WANG Jun1，2，3，LUO Pan4，LIU Feiyu4，HU Xiuqing1，2，3 |
(1. Architecture and Civil Engineering College，Wenzhou University，Wenzhou，Zhejiang 325035，China；2. Key Laboratory of Engineering and Technology for Soft Soil Foundation and Tideland Reclamation of Zhejiang Province，Wenzhou University，Wenzhou，Zhejiang 325035，China；3. Collaborative Innovation Center of Tideland Reclamation and Ecological Protection，
Wenzhou University，Wenzhou，Zhejiang 325035，China；4. Department of Civil Engineering，Shanghai University，
Shanghai 200072，China) |
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Abstract The soil elements within a slope or behind a retaining wall are subjected to the initial static shear stress prior to cyclic loading，and there exists an angle between the directions of initial static shear stress and cyclic loading under earthquake or wave loading. In order to investigate the effects of the angle between the directions of the initial static stress and cyclic loading on the softening index of soil，a series of tests were carried out using dynamic simple shear apparatus. The test results indicate that the softening index ? decreases with the increasing of cyclic shear stress ratio rc with a certain angle θ between the directions of cyclic loading and initial static shear stress. The difference of the loading cycles obtained from a certain value of δ corresponding to the two neighboring rc decreases. The softening index increases as the angle grows from 0° to 90°with a certain rc . An opposite evolution of softening index was observed for 90°＜θ≤180°. At the initial stage of cyclic loading，the softening index for θ = 120°，150°，180° is larger than that for θ = 60°，30°，0° when rc = 0.15，respectively. The softening index model and the model of pore pressure ratio versus softening were established through analysis of data regression.
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2016, Vol. 35 
