运用最新研制的80 t三维多功能土工试验机对粗粒土与结构接触面在3种典型法向边界条件下的三维力学特性进行了试验研究。结果表明，接触面法向边界条件对其力学特性有重要影响，不同法向边界条件下接触面表现出了一些相似和不同的力学响应：(1)接触面总体上剪缩或有剪缩趋势，但数值不同；(2)除常应力条件外，接触面切向应力-切向位移关系曲线同一循环内一般不闭合，不同循环也不重合；(3)3种法向边界条件下接触面应力比-切向位移关系曲线同一循环内基本闭合，不同循环也基本重合，且形状较为相似，均呈椭圆形；(4)接触面静、动抗剪强度指标随法向边界条件变化不大，但动抗剪强度则差别很大。

By using a new apparatus called 80t 3D Multifunction Apparatus for Soil mechanics, 3D cyclic behavior of gravel-structure interface was studied under three typical normal boundary conditions generally used in laboratory experiments. The test results indicate that the normal boundary condition has great influence on the behavior of the interface, which presents similar or different behaviors: (1) Volume or volumetric trend of the interface generally presents compressive response due to shear application, but the values are different. (2) The curves between shear stress and tangential displacement are unclosed in the same cycle and not coincident in different cycles, except those under constant normal stress condition. (3) The curves between stress ratio and tangential displacement are all closed, coincident and like ellipse under different normal boundary conditions. (4) The monotonic and cyclic friction angles of the interface are similar, but the cyclic shear strengths are significantly different.

973项目课题（No. 2007CB714108）；国家自然科学基金资助项目（No. 50979046）。