上软下硬地层盾构开挖面稳定性计算模型  

Calculation Model of Shield Tunnel Face Stability in Upper-Soft and Lower-Hard Strata

作　　者：刘泉维 邵小康 黄成 李琛 叶守杰 江玉生[2] 杨志勇[2] LIU Quanwei;SHAO Xiaokang;HUANG Cheng;LI Chen;YE Shoujie;JIANG Yusheng;Yang Zhiyong(Qingdao Metro Line 6 Co.,Ltd.,Qingdao Shandong 266100,China;School of Mechanics and Civil Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China)

机构地区：[1]青岛市地铁六号线有限公司,山东青岛266100 [2]中国矿业大学(北京)力学与土木工程学院,北京100083

出　　处：《中国铁道科学》2024年第4期111-119,共9页China Railway Science

基　　金：国家自然科学基金资助项目(U1261212)。

摘　　要：针对上软下硬地层失稳特点,在假定开挖面附近因土体失稳而由软硬地层分界线先向上诱发形成部分楔形体、再呈倒圆台状向地面发展的基础上,提出开挖面稳定性计算模型。先基于极限平衡法提出部分楔形体计算模型;再依据修正后的楔形体计算模型,分别计算上覆土压力和开挖面前方部分楔形体的受力;最后依托青岛地铁6号线某区间工程开展数值模拟,验证理论模型。结果表明:不同支护应力比条件下的土体变形范围有所差异,土体变形主要发生在开挖面前方和上方并呈泡状延伸;数值模拟得到的开挖面失稳形态基本符合理论计算模型的假定形状;理论计算得到该例盾构开挖面极限支护应力比为0.21,与数值模拟的误差率为5%;当开挖面支护力小于极限支护力时,上软下硬地层开挖面水平变形会突然迅速增大;开挖面附近的岩土体变形主要发生在上部软弱部分,最大水平位移出现在上部软土中心附近,开挖面上土体最大水平位移与开挖面上方地表最大竖向位移间的相关性较高,两者变形规律类似。In response to the instability characteristics of the upper-soft and lower-hard strata,a stability calculation model for the tunnel face was proposed based on the hypothesis that the boundary between soft and hard strata caused by soil instability near the tunnel face first induced the formation of partial wedge-shaped bodies upward,and then developed into inverted conical shapes toward the ground.Firstly,the calculation model of partial wedge-shaped body was proposed through the limit equilibrium method.Subsequently,according to the modified calculation model of wedge-shaped body,the overlying soil pressure and the forces acting on the partial wedge-shaped body in front of the tunnel face were calculated respectively.Finally,relying on a tunnel section project of Qingdao Metro Line 6,numerical simulations were conducted to verify the theoretical model.The results showed that the soil deformation range under different conditions of supporting stress ratio was different,and the deformation mainly occurred in front of and above the tunnel face with the extension of bubble-like shape.The instability shape of tunnel face obtained from the numerical simulation basically accorded with the assumed shape of theoretical calculation model.The limit supporting stress ratio of the shield tunnel face obtained from the theoretical calculation was 0.21,with an error rate of 5%compared to the numerical simulation results.In addition,when the supporting stress of tunnel face was less than its limit value,the horizontal deformation of tunnel face in upper-soft and lower-hard strata would suddenly increase rapidly.The deformation of rock and soul near the tunnel face mainly occurred in the upper weak sections,and the maximum horizontal displacement appeared near the center of the upper-soft soil.There was a high relevance between the maximum horizontal displacement of soil on the tunnel face and the maximum vertical displacement of surface above it,both exhibiting similar deformation patterns.

关 键 词：盾构隧道 上软下硬地层 开挖面稳定性 极限平衡法 数值模拟 

分 类 号：U455.43[建筑科学—桥梁与隧道工程]