采用大型直剪仪进行了黏性土、砂土两种土样与混凝土接触面的直剪试验，研究了不同法向应力条件下，土与混凝土接触面上的应力、应变及破坏强度等特征． 试验结果表明:对于黏性土与混凝土接触面的剪切加载，剪切过程表现出应变软化特性，残余应力水平趋于稳定状态;砂土与混凝土接触面的剪切过程主要表现为应变硬化，残余应力缓慢增长． 针对土与结构接触面剪切特性，从损伤力学理论出发提出了考虑应变硬化和软化特性的结构接触面剪切损伤本构模型及模型参数确定的方法． 该模型能充分反映土 － 结构接触面的应变软化和硬化特性，参数较少，方便实用．

The direct shear tests of the interfaces between the concrete and the cohesive soil as well as the sandy soil were conducted by using a large direct shear apparatus,and the stress,strain and failure strength of the inter- faces were investigated under different normal stresses.The results show that the cohesive soil and concrete inter- face has a strain-softening characteristic during the shear,and the residual stress tends to be a constant,and that the sandy soil and concrete interface has a strain-hardening characteristic during the shear,and the residual stress slowly increases.In order to investigate the shear characteristics of the soil and structure interface,by introducing the damage mechanics theory,a constitutive model of shear damage,which considers the strain-hardening and sof- tening characteristics,is constructed,and a method of determining the model parameters is proposed.The con- structed damage model can reflect the strain-softening and hardening characteristics of the soil and structure inter- face with less model parameters,and it is both convenient and practical.