非共面双裂隙层状岩石破坏特征及工程应用

Failure Characteristics and Engineering Application of Layered Rock with Two Pre-existing Non-coplanar Fissures

为了研究层状岩石在预存裂隙作用下的破坏机理,基于颗粒离散元理论,构建能反映岩石各向异性特征的数值模型.基于该模型,系统研究了含非共面双裂隙层状岩石在单轴压缩条件下裂纹的产生与演化规律,并揭示了双裂隙层状围岩中隧道开挖后岩体的破坏模式.研究结果表明:存在预制裂隙的岩石,其抗压强度值小于相同条件下的完整岩石,但岩石强度与层理面倾斜角度的关系曲线仍呈U形分布;竖向加载时,试样的破坏形态同层理面倾斜角度(β)与预制裂隙倾斜角度(α)间相对大小有关.当β<α时,岩石的破坏受预制裂隙控制;当β>α时,岩石的破坏可分为预制裂隙与层理面共同控制与层理面控制两类;隧道围岩的细观破坏模式也与β、α的相对大小有关,但破坏区域均集中在洞周两侧垂直于层理面的一定范围内.

In order to study the failure mechanism of layered rock with pre-existing cracks,a numerical model which is based on particle discrete element method and can reflect the anisotropic characteristics of rock is built.The initiation and propagation of micro-cracks in anisotropic rock with two pre-existing non-coplanar fissures under uniaxial compression tests are analyzed.Furthermore,the failure process of surrounding rock after tunnel excavation is also obtained.Results shows that,the compressive strength of specimens with pre-existing fissures is smaller than that of intact rock,while the curve of relationship between strength and inclination angles is still‘U’shaped.The failure patterns are controlled by inclination angle of bedding plane(β)and inclination angle of fissures(α).Forβ<α,failure is controlled by fissures;forβ>α,failure is controlled by both fissures and bedding planes or bedding planes.Failure patterns of surrounding rock is also related toβandα,while the damage zone is concentrated in certain regions around the tunnel in the direction normal to layers in all cases.