泥水盾构开挖面失稳破坏的颗粒流模拟研究  

Research on Particle Flow Simulation for Excavation Face Instability of Slurry Shield

作　　者：王振飞[1] 张成平[1] 

机构地区：[1]北京交通大学城市地下工程教育部重点实验室,北京100044

出　　处：《中国铁道科学》2017年第3期55-62,共8页China Railway Science

基　　金：中央高校基本科研业务费专项资金资助项目(2016JBM042)

摘　　要：针对北京砂卵石地层大直径泥水盾构隧道开挖面稳定性和地表沉降的问题,采用颗粒流程序PFC2D研究砂卵石地层土体的颗粒流细观参数,从土体颗粒的摩擦系数和接触模量以及泥膜的厚度和黏合强度对开挖面的作用效果进行分析和评价。结果表明:土体的颗粒摩擦系数和接触模量以及泥膜的厚度和黏合强度对开挖面的稳定性有显著影响;土体颗粒的摩擦系数和接触模量越小,开挖面破坏越严重,地层坍塌轮廓越大,地表沉降槽越深;当土体颗粒的摩擦系数增大到2.4、接触模量增大到12×107 N·m^(-1)时,开挖面趋于稳定,地表沉降槽曲线平缓,地表竖向位移较小;泥膜的厚度和黏合强度越小,开挖面挤出变形越显著,越容易引起较大范围的地层变形,从而导致地表塌陷;当泥膜的厚度为20mm且泥膜黏合强度为1 400N·m^(-1)时开挖面稳定。Aiming at excavation face stability and ground surface settlement for large-diameter slurry shield driving in sand gravel stratum in Beijing, particle flow code PFC^2D was conducted to examine the micro-pa rameters of particle flow model for sandy cobble ground. Moreover, the friction coefficient and contact modulus of soil particle, the thickness and strength of mud membrane, were used for analyzing and evaluating the effect of tunnel face. Results show that： the friction coefficient and contact modulus of soil particle as well as the thickness and strength of mud membrane have significant influence on the stability of excavation face. The smaller the friction coefficient and contact modulus of soil particle are, the more serious failure of the excavation face is and the larger the boundary of ground collapse becomes, and the deeper ground settlement trough is. When the friction coefficient of soil particle reaches to 2.4 and its contact modulus reaches to 12×10^7 N·m^-1, the excavation face tends towards stabilization. Moreover, the curve of settlement trough is flat and the vertical displacement of ground surface is smaller. The smaller the thickness and strength of mud membrane are, the more obvious the extrusion of the excavation face is, which can easily cause a wide range of ground deformation, and directly leading to ground collapse. When the thickness of mud membrane reaches to 20 mm and its strength reaches to 1 400 N·m^-1 , the stability of excavation face can be ensured during construction.

关 键 词：砂卵石地层 泥水盾构 开挖面稳定 颗粒流细观参数 泥膜 数值模拟 颗粒流程序 

分 类 号：U451[建筑科学—桥梁与隧道工程]