静水压力条件下开挖直径及卸荷时间对巷道围岩变形-开裂影响的连续-非连续方法模拟  

Numerical simulation of effects of the excavation unloading time and chamber diameter on deformation-cracking processes of the chamber surrounding rock under hydrostatic pressure

作　　者：王学滨 芦伟男[2] 钱帅帅 白雪元 Wang Xuebin;Lu Weinan;Qian Shuaishuai;Bai Xueyuan(Institute of Computational Mechanics,Liaoning Technical University,123000,Fuxin,China;College of Mechanics and Engineering,Liaoning Technical University,123000,Fuxin,China)

机构地区：[1]辽宁工程技术大学计算力学研究所,阜新123000 [2]辽宁工程技术大学力学与工程学院,阜新123000

出　　处：《应用力学学报》2020年第4期1841-1848,I0032,共9页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(51874162);辽宁省百千万人才工程项目(2017)。

摘　　要：以自主开发的拉格朗日元与变形体离散元耦合的连续-非连续方法为基础,引入Ⅱ型断裂能,用以模拟剪切开裂现象,并通过直接剪切实验对方法的正确性予以验证。在静水压力条件下,开展了关于巷道开挖直径、开挖卸荷时间对巷道围岩变形及开裂过程影响的数值模拟研究。研究结果表明:岩样上端面平均剪应力-水平位移曲线的峰值随着Ⅱ型断裂能的增加而增加,且岩样脆性降低;随着时步数的增加,多条剪裂纹自巷道周边向围岩内部扩展,部分剪裂纹相互交叉而形成Ⅴ形坑,最终使围岩处于不平衡或趋于平衡的状态;在此过程中剪裂纹时而扩展,时而基本停滞,并在一些位置呈间隔排列;随着开挖直径的减小,Ⅴ形坑的最大深度减小,剪裂纹区段数目及平行的剪裂纹数目均减少,当开挖直径较小时,模型最终趋于平衡;开挖卸荷时间不同,巷道围岩开裂呈现一定的规律性和复杂性。In order to simulate the shear fracture, the Ⅱ-type fracture energy is introduced into the developed continuum-discontinuum method in which the Lagrangian element method and deformational discrete element method are combined together. The proposed method is verified through a numerical simulation of the direct shear test. With an increase of the Ⅱ-type fracture energy, the peak of the relation between the averaged shear stress acting at the top increases and the brittleness of the specimen decreases. Effects of the excavation unloading time and chamber diameter on the deformation and cracking processes of the chamber surrounding rocks under hydrostatic pressure are studied numerically. Following results are obtained. With an increase of the number of time steps, several shear cracks extend toward the depth of the surrounding rock, and a few cracks cross each other to form Ⅴ-shaped notches. Eventually, the surrounding rocks are in equilibrium state or not. In this process, shear crack propagation is intermittent. At some positions, there are approximately parallel shear cracks. With a decrease of the chamber diameter, the number of shear crack segments decreases, the maximum depth of Ⅴ-shaped notches decreases, and the number of approximately parallel shear cracks also decreases. For a small chamber, the surrounding rocks easily reach an equilibrium state. Effects of the excavation unloading time on the cracking process exhibit a certain regularities and complexities to some extent.

关 键 词：连续-非连续方法 静水压力 开挖卸荷 巷道直径 剪切开裂 Ⅴ形坑 

分 类 号：O39[理学—工程力学]