圆形巷道围岩剪切带形成过程的能量释放模拟  

Modeling of the Energy Release during the Shear Band Formation in the Circular Tunnel Surrounding Rock

作　　者：王学滨[1] 伍小林[1] 潘一山[1] 

机构地区：[1]辽宁工程技术大学力学与工程学院,辽宁阜新123000

出　　处：《地下空间与工程学报》2014年第1期43-50,共8页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金项目(51374122);国家重点基础研究发展计划(2010CB226803);辽宁省煤矿液压技术与装备工程研究中心(辽宁工程技术大学)开放基金(CMHT-201205)

摘　　要：利用FLAC模拟不同侧压系数条件下圆形巷道围岩破坏过程中的能量释放规律,着重考察V形坑及短剪切带形成过程中的剪切破坏的单元数及应变能释放率的演变规律。在计算中,采用初始化模型内部正应力的方法,利用应变软化的本构关系,采用"先加载,后挖洞"方式。模拟结果表明,当剪切破坏单元仅位于巷道的表面上时及深入围岩很浅时,剪切应变能释放率的值很低,呈"脉冲式"及"振荡式"特点;当短剪切带形成后向围岩中传播时,其呈"激增式"特点。对本文模型和传统的轴对称模型的差别进行了讨论。在本文的内圆外方的模型中,剪切应力尽管没有初始化,在加载后也会存在,因此不属于轴对称模型。剪应力的存在及变化是V形坑及短剪切带发生及发展的主要因素。侧压系数的提高使剪切应变能释放率的峰值提高,两种能量释放现象提前,破坏单元数提高。The released energy in the failure process of a circular tunnel surrounding rock at different lateral pressure coefficients is modeled using FLAC. The emphasis is put on the formation of V-shaped notches and short shear bands. In the present calculation, the normal stresses are initialized in the model~ a strain-softening constitutive relation is used; and a tunnel is excavated after the model is loaded to reach a static equilibrium state. Numerical re- sults show that when the failed elements in shear are located at the tunnel surface or when they just extend toward the surrounding rock, the shear strain energy release rate is low, exhibiting pulse and oscillation characteristics. Howev- er, after the formation of short shear bands, the shear strain energy release rate exhibits rapidly increasing character- istics when they propagate toward the depth of the surrounding rock. The difference between the present model and the traditional axisymmetric thick-wall barrel model is discussed. In the present model, the shear stress is not initial- ized and it will exist after the model is loaded at its outer surfaces. Therefore, the model is not axisymmetric. The for- mation of V-shaped notches and short shear bands stems from the existence of the shear stress. As the lateral pressure coefficient increases, the peaks of the shear strain energy release rate rise ; the phenomena of the released energy in shear and in tension become earlier; and the number of failed elements increases.

关 键 词：侧压系数 V形坑 能量释放 圆形巷道 剪切破坏 

分 类 号：TU45[建筑科学—岩土工程] TD322[建筑科学—土工工程]