不同含水率软弱结构面剪切蠕变试验及模型研究

Experimental and theoretical studies on the effects of water content on shear creep behavior of weak structural plane of sandstone

软弱结构面的蠕变特性是岩体重要力学特性之一,其蠕变特性常控制着岩体的蠕变变形和长期强度。软弱结构面中充填物的含水率是影响其蠕变特性的重要因素之一,通过开展不同含水率砂岩软弱结构面剪切蠕变试验,得到了具不同含水率的砂岩软弱结构面剪切蠕变试验曲线。基于得到的剪切蠕变试验曲线,分析了含水率对软弱结构面剪切蠕变特性及长期抗剪强度的影响规律。最后通过模型辨识,采用改进的粘弹塑性模型来描述考虑含水率变化的砂岩软弱结构面蠕变特性。

Creep behavior of weak structural plane is one of the most important mechanical characteristics of rock mass and always has an important influence on deformation and long-term strength of rock mass. Water content of the fillings is a significant factor influencing the creep properties of the weak structural plane. In this study, by multi-stage loading, a series of shear creep tests on the weak structural plane of sandstone with different water contents are conducted. The curves of the shear creep deformation vs. time under different water content of the fillings are derived. The effects of water content on the shear creep behavior and long-term shear strength of weak structural plane of sandstone are analyzed. Compared with the shear strength by rapid shear test, the long-term strength has sharply decreased. Based on the test results and analysis, modified viscoelastoplastic model is identified to describe the behavior of water content influencing on the weak structural plane of sandstones and parameters of this model are also given through back analysis.