高水平应力环境下层状岩体隧道稳定性分析  

Layered rock mass tunnel stability analysis under high horizontal stress

作　　者：苗秋福 MIAO Qiufu(Shanxi Xiyang-Yuci Expressway Co.,Ltd.,Jinzhong,Shanxi 030611,China)

机构地区：[1]山西昔榆高速公路有限公司,山西晋中030611

出　　处：《公路交通科技》2025年第2期196-206,共11页Journal of Highway and Transportation Research and Development

基　　金：山西交控路桥集团企业课题(20-JKKJ-52)。

摘　　要：【目标】研究层状岩体隧道在高水平构造应力环境下开挖的破坏机制与稳定性问题。【方法】以太行山隧道穿越层状砂质板岩为背景,通过建立PFC2D离散元隧道开挖数值模型,研究了侧压系数、结构面间距和结构面倾角变化对隧道稳定性及破坏模式的影响。【结果】当岩层与主应力的方向平行或正交时,裂纹数目明显小于与主应力斜交的工况。倾斜岩层条件下,主地应力方向为竖向时,隧道围岩开挖后断裂规模大于水平方向工况,对于水平岩层与陡立岩层这一结果相反。岩层倾角决定了隧道围岩的破坏模式。在水平构造应力影响下,水平岩层破坏为岩层挤压卸荷后的脆断,倾斜岩层则是发生压弯折断与剪切断裂,垂直和陡立岩层受力呈现固端梁的弯曲特征。水平岩层工况中隧道围岩变形最小,倾斜岩层变形最大,围岩最大变形为垂直岩层走向的拱部与底部位置,陡立与垂直岩层的变形呈现“蝴蝶”状,以边墙处的弯曲折断挤压变形为主。【结论】岩层的厚度直接影响了岩层的承载能力。水平岩层在中厚及薄层时(层厚<0.5 m)较容易引发较大规模的断裂事件,倾斜岩层在厚层0.5~1.0 m及以下时容易发生大规模的断裂侵限事件,而陡立岩层在厚层0.5~1.0 m及以下时容易发生大规模的断裂事件。[Objective]The layered rock mass tunnel excavation failure mechanism and stability under high horizontal tectonic stress were studied.[Method]The Taihang mountain tunnel,crossing layered sandy shale,was taken as the study background.The influences of lateral pressure coefficient,structural plane spacing and structural plane inclination variation on tunnel stability and failure mode were studied by establishing PFC2D discrete element tunnel excavation numerical model.[Result]When the rock layers are parallel or orthogonal to the principal stress direction,the number of cracks is significantly lower than that under oblique conditions.Under inclined rock layer conditions,the fracture scale after surrounding rock excavation is greater in the vertical stress condition than that under horizontal stress conditions.For horizontal and vertical layers,the result is opposite.The rock layer angle determines the surrounding rock failure mode.Under horizontal structural stress,the horizontal rock layer failure occurs as brittle fracture after rock mass squeezing and unloading.While the inclined rock layer exhibits compression bending and shearing fractures.The vertical and steep rock layers display a fixed-end beam bending characteristic.Among different rock layer scenarios,the minimal deformation is observed under horizontal rock layer conditions,while the maximal deformation occurs under inclined rock layer conditions,particularly at the arch and bottom in vertical rock layer direction.The steep and vertical rock layers show the butterfly-shaped deformation,with bending,fracturing,and squeezing deformation predominating at sidewalls.[Conclusion]The rock layer thickness directly affects the rock layer bearing capacity.The horizontal rock layers are prone to large-scale fracture events under medium thick and thin layer conditions(thickness<0.5 m).The inclined rock layers are prone to large-scale fracture intrusion events when the thickness is 0.5-1.0 m and below.The steep rock layers are prone to large-scale fracture events wh

关 键 词：隧道工程 破坏模式 离散元模拟 层状岩体 高水平应力 

分 类 号：U459.3[建筑科学—桥梁与隧道工程]