红层泥岩桩岩接触面本构模型试验及数值模拟

桩-岩（土）接触面力学特性的研究是桩基承载机理研究的基础。通过红层泥岩桩岩接触面大型直剪试验，研究了红层泥岩桩岩接触面的力学特性，结果表明：接触面剪应力先随剪切位移增大而增大，在达到峰值后，剪应力随着剪切位移增大而降低，并最终趋于稳定值，应力应变曲线呈现出应变软化的特征。根据剪切试验结果，推导出桩岩接触面应变软化本构方程。利用fish语言对FLAC^3D中自带的理想弹塑性接触单元进行二次开发，并应用开发的模型对桩岩接触面直剪试验进行了数值模拟，分析剪应力与剪切位移之间的关系，证明了该本构能够较好地模拟接触面间的应变软化特性。

Interface constitutive model test and numerical simulation of red mudstone pile-rock

The pile-rock(soil) interface mechanical behavior was the basis of pile foundation bearing mechanics. Firstly, the mechanical property of the interface was investigated through the laboratory large direct shear test of red mudstone pile-rock interface. The results indicated that the shear stress-strain curve presented strain softening behavior. The shear stress was increasing with the shear strain initially, and when the shear stress came to a peak, the shear stress was decreasing with the shear strain and finally reached a steady. Subsequently, the constitutive equation was deduced based on the interface mechanical property, the ideal elastic-plastic contact element in FLAC^3D was further developed through fish language. Additionally, the direct shear test of red mudstone was simulated according to the interface constitutive model, and the relationship of shear stress and shear displacement between the pile and soil were analyzed which proved that the constitutive model showed good performance on simulating strain softening features of the interface.