考虑节理倾角的岩体损伤本构模型及强度准则

A damage constitutive model and strength criterion of rock mass considering the dip angle of joints

针对不同倾角单一贯通节理岩体,提出了初始节理损伤、荷载损伤和总损伤的概念;利用损伤力学理论,综合考虑岩体结构效应与荷载耦合作用,建立节理岩体损伤演化模型及损伤本构模型;基于多元函数全微分法则,构建了考虑节理倾角影响的节理岩体强度准则。然后对模型进行验证分析,结果表明:所建立的模型理论曲线与实测曲线高度吻合,验证了模型的正确性;初始节理损伤随节理倾角先增大后减小,总体呈现倒"U"型分布规律;初始节理损伤最大值与最小值之比达到2.13,表明节理倾角对节理岩体初始损伤影响较大;总损伤演化曲线随节理倾角增大先缓慢上升,然后快速上升,最后又缓慢上升趋于1,总体呈"S"型分布规律;总损伤率随应变增加先增大后减小,总体呈现正态分布规律;总损伤率随节理倾角先减小后增大,总体呈"U"型分布规律;随围压增大,总损伤和总损伤率均有一定的减小,表明围压对损伤演化具有一定的抑制作用。

For the single continuous jointed rock mass with different dip angles,the concepts of initial joint damage,load damage and total damage were proposed. Based on the damage mechanics,a damage evolution model and a damage constitutive model were established considering the coupling of structural effect and loading. The method of total differential was employed to establish the strength criterion of jointed rock mass considering the effect of the dip angle of joints. The models were verified and analyzed. The theoretical curves of the models constructed in this paper agree with the experimental result,which verifies the correctness of the models. The initial joint damage shows an inverted U-type distribution that increases first and then decreases with the increase of the dip angle of joints. The ratio of the maximum to minimum values of the initial joint damage reaches 2.13,indicating that the dip angle of joints has a great influence on the initial damage of the jointed rock mass. The total damage curve shows an S-type distribution that rises slowly first,then rises rapidly and finally rises slowly to 1 with the increase of the dip angle of joints. The total damage rate curve shows a normal distribution that increases first and then decreases with the increase of the strain and a U-type distribution that decreases first and then increases with the increase of the dip angle of joints. The total damage and total damage rate decrease with the increase of confining pressure,indicating that the confining pressure has an inhibitory effect on the damage evolution.