考虑法向应力历史的黏土–混凝土界面弹塑性分析

土与混凝土接触界面剪切力学特性研究对桩基础设计至关重要，非挤土桩施工过程中由于成孔卸荷或桩身混凝土凝结造成界面附近土体径向卸荷，径向荷载的变化势必改变桩土界面的荷载传递规律。通过大型结构剪切试验发现：法向应力的变化历史对黏土–混凝土接触面剪切变形特性和强度参数影响明显。为给钻孔灌注桩桩土接触界面数值模拟提供合理的剪切力学模型，以接触界面积累的能量为硬化参数，假定接触界面剪切过程为界面积累能量对外做功的过程，考虑法向应力历史对剪切刚度的影响，提出考虑法向应力历史的黏土–混凝土界面模型，并介绍各模型参数的确定方法。模型原理清晰，参数物理意义明确。通过大型直剪试验成果数据对界面模型进行验证。结果表明：提出的模型能准确地再现和预测不同法向应力历史条件下的黏土–混凝土接触界面的力学特性。

ELASTOPLASTIC ANALYSIS OF INTERFACE BETWEEN CLAY AND CONCRETE CONSIDERING EFFECT OF NORMAL STRESS HISTORY

The behavior of soil-structure interface is crucial to the design of pile foundation.The radial unloading occurs during the process of hole boring and concrete curing,which will effect the load transfer rule of pile-soil interface.Through the large shear tests on interface between clay and concrete,it can be concluded that the normal stress history influences significantly the shear behavior and strength parameter of interface.The numerical simulation of bored shaft-soil interaction problem requires proper modeling of the interface.Through taking the energy on the interface as a hardening parameter and viewing the shearing process of interface as the process of the accumulated energy dissipated to do work,considering the influence of normal stress history on the shearing rigidity,a mechanical model of interface between clay and concrete is put forward to take the effect of normal stress history into consideration.Then,The determination methods for the model parameters are introduced.The model based on a legible mathematical theory and all its parameters have definite physical meaning.The model is validated through the data from direct shear test.The results show that the model can reproduce and predict the mechanical behavior of interface between clay and concrete under arbitrary normal stress histories.