圆形巷道围岩变形破坏的连续–离散耦合分析

基于有限差分理论及颗粒流理论,以FLAC及PFC程序为实现平台,将颗粒体模型嵌入有限差分网格内部空域,采用fish语言编译连续元与离散元计算数据传输交换函数,建立二维平面应变圆形巷道连续–离散耦合分析模型,从宏–细观角度深入开展不同围压条件下圆形巷道围岩变形破坏机制的研究。研究表明:(1)在低围压条件下,巷道开挖围岩发生弹性变形。当水平围压与垂直围压相等,相同径向距离处的围岩变形量近似相等,均指向圆心。(2)在高围压条件下,当侧压系数K1,围岩破坏主要集中在巷道顶板、底板,当侧压系数K1,围岩破坏主要集中在巷道两帮。围岩破坏形态均呈"毡帽形",帽口朝向巷道中心。(3)在高围压条件下,随着围压不断提高,破裂总数逐渐增多,而破裂孕育扩展时间不断延长。当侧压系数K=1,围岩破坏表现出明显的分区破裂化现象。

DEFORMATION AND FAILURE ANALYSIS ON SURROUNDING ROCK OF CIRCULAR TUNNEL USING COUPLED CONTINUUM-DISCRETE METHOD

Based on finite difference and particle flow theory，FLAC and PFC code were used as implementation platform. Bonded particle model was embedded in finite difference grid，and communication function of computational data between continuum and discrete element was compiled using fish language. The coupled continuum-discrete model of circular tunnel in 2D plane strain mode was constructed and used to investigate the deformation and failure mechanism of surrounding rock with different confining stress from macro-meso viewpoint. The research resualts are as follows：(1) With lower confining stress，elastic deformation generates in surrounding rock after tunnel excavation. When horizontal and vertical confining stress are equal，the deformation value of surrounding rock with identical radial distance are the same，and directing the tunnel center. (2) Under the condition of higher confining stress，the failure of surrounding rock mainly generates in the upper and bottom plate of tunnel with side pressure coefficient K＞1，while the failure of surrounding rock mainly generates in the tunnel sides with K＜1. Both the failure mode of surrounding rock are the shape of felt cap，with the cap mouth directing the tunnel center. (3) With higher confining stress，the amount of crack increases and the evolution time of crack extends continually with the increase of confining stress. Meanwhile，the failure of surrounding rock exhibits obvious zonal disintegration phenomenon with K = 1.