危岩体断裂特性的网格重构数值仿真研究

危岩体稳定是三峡库区的主要关注点之一。为探究不同裂纹赋存形态以及不同降雨工况下危岩体断裂的变形特性,基于围道积分原理,在Abaqus平台上利用Python语言开发了基于断裂力学理论的危岩体任意裂纹扩展的网格重构数值模拟方法,该方法与以往危岩体裂纹扩展数值模拟方法相比,能够体现危岩体裂纹尖端的断裂力学特征,实现连续介质中的非连续表达。利用此方法对重庆市万州太白编号为W15的危岩体稳定性进行了数值仿真研究,结果表明:提出的基于断裂力学理论的网格重构新型数值模拟方法在危岩体裂纹扩展研究中的适应性良好,为危岩体断裂变形特性模拟提供了一种新的数值模拟方法;危岩体的最大主应力值和剪应力值随着裂隙角度的增大呈现先增后减的趋势,危岩体的水平位移值随着裂隙倾角的增大持续减小;随着裂隙角度的增大,裂隙对危岩体变形的影响逐渐减小,危岩体的水平位移主要集中于危岩体的突出部位;危岩体裂隙长度的增大对危岩体应力及变形的影响最大,使得危岩体的变形由危岩体的突出部位向裂隙处集中;暴雨工况下危岩体的变形及位移较之天然工况要大,是影响危岩体稳定的重要因素之一;危岩体裂纹朝着危岩体的突出部位进行扩展,主要受到Ⅰ型扩展主导,随着裂纹的不断扩展,危岩体裂纹尖端的Ⅰ型应力强度因子呈现指数型上升,Ⅱ型应力强度因子变化不大,危岩体初始裂纹长度越长,危岩体裂纹尖端的Ⅰ型应力强度因子和Ⅱ型应力强度因子的绝对值越大。

Numerical Simulation Study on Grid Reconstruction for Fracture Characteristics of Dangerous Rock Mass

The stability of dangerous rock mass is one of the main concerns in the Three Gorges Reservoir Area.In order to explore the fracture shape characteristics of dangerous rock mass under different crack occurrence and different rainfall conditions,this paper develops a new numerical simulation method for crack propagation based on the principle of circumference integral and the fracture force method has been developed on Abaqus platform with Python language.Compared with the previous numerical simulation methods of crack propagation,this method can reflect the fracture mechanics characteristics of the crack tip,and the mesh reconstruction method can realize the discontinuous expression in continuous media.Based on this,the paper carries out numerical simulation of W15 dangerous rock mass in Taibai,Chongqing.The results show that the new method of grid reconstruction based on the fracture force method has good adaptability and it provides a new numerical simulation method for fracture deformation cha-racteristics simulation of dangerous rock mass,and with the increase of fracture angle,the normal stress value and shear stress value of dangerous rock body first increase and then decrease,and the horizontal displacement value decreases continuously with the increase of fracture angle.With the increase of fracture angle,the effect of fracture on the deformation of dangerous rock mass decreases gradually,and the horizontal displacement mainly focuses on the protruding part of dangerous rock mass.The increase of fracture length has the greatest influence on the stress and deformation of dangerous rock mass,which makes the deformation concentrate from the protruding part of the dangerous rock mass to the fracture.The deformation and displacement of dangerous rock under heavy rain are larger than that under natural conditions,which is one of the most important factors affecting the stability of dangerous rock mass.The cracks of dangerous rock mass propagate towards the protruding part,which is mainly dominated by mode I propagation.With the continuous crack propagation of cracks,modeⅠstress intensity factor increases exponentially,while modeⅡstress intensity factor changes little.The longer the initial crack length,the greater the absolute value of modeⅠstress intensity factor and modeⅡstress intensity factor.