TEST INVESTIGATIONS ON 3D STRESS-CONTROLLED CYCLIC BEHAVIOR OF GRAVEL-STRUCTURE INTERFACE
FENG Dakuo1,2,HOU Wenjun3,ZHANG Jianmin1,2
(1. State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China;2. Institute of Geotechnical Engineering,Tsinghua University,Beijing 100084,China;3. Department of Building Energy Efficiency and Science and
Technology,Ministry of Housing and Urban-rural Development of People's Republic of China,Beijing 100835,China)
Abstract:Applied with a large-scale direct shear apparatus,the 3D stress-controlled cyclic behavior of a gravel- structure interface was investigated and the influence of the shear path and stress amplitude was discussed. The tests were performed at normal stress of 400 kPa in two-way cross,one-way and two-way circular cyclic shear paths. Results indicate that:(1) The volumetric change of interface between coarse grained soil and structure can be divided into reversible and irreversible components in two-way cyclic shear paths. (2) Irreversible increment is dominant in the first few shear cycles,and then equivalent to reversible component which finally becomes the governing part of interface volumetric increment;but the volumetric change of interface gives priority to irreversible component. (3) Tangential displacement migrates with shear cycles. Interface exhibits non-coaxial behavior in the tangential direction for circular shear tests;tangential displacement amplitude and increment per shear stress decrease with shear cycles when the shear stress amplitude is relatively small. (4) With the increasing shear stress amplitude,non-coaxial angle decreases and tangential displacement and tangential displacement increment per shear stress both increase. Non-coaxial angle varies little with shear cycles in one-way circular shear path,while it has opposite algebraic sign at neighboring shear cycles in two-way circular shear path. (5) Tangential stress-tangential displacement curves present an elliptical shape in circular path and hyperbolic in cross shear path. Shear path and shear stress amplitude have notable influence on the 3D stress-controlled cyclic behaviors of interface.