基于RPM方法的隧道开挖地层失稳模式及形成机理研究  

Study on Ground Instability Modes and Formation Mechanisms Induced by Tunnel Excavation Using the RPM Method

作　　者：路德春[1] 张富军 董宏宇 林庆涛 史磊磊 杜修力[1] LU Dechun;ZHANG Fujun;DONG Hongyu;LIN Qingtao;SHI Leilei;DU Xiuli(Institute of Geotechnical and Underground Engineering,Beijing University of Technology,Beijing 100124,China;Beijing Municipal Construction Group Co.Ltd,Beijing 100089,China)

机构地区：[1]北京工业大学岩土与地下工程研究所,北京100124 [2]北京市政建设集团有限责任公司,北京100089

出　　处：《应用基础与工程科学学报》2024年第4期926-943,共18页Journal of Basic Science and Engineering

基　　金：国家自然科学基金项目(52025084,52208396);国家重点研发计划项目(2022YFC3800901)。

摘　　要：基于材料破坏时邻近颗粒间相对运动的特征,提出了颗粒相对运动(RPM)指标描述材料的渐进破坏行为;考虑颗粒的平动和转动,建立了RPM计算的方法;基于PFC2D平台实现了RPM与离散元方法的结合,发展了颗粒材料破坏分析方法,并利用活动门试验结果验证了其描述岩土材料破坏过程的合理性.以北京地铁12号线暗挖隧道为背景建立数值模型,分析了隧道开挖时不同地层的破坏渐进过程和失稳模式.均质砂土和黏土地层最终都呈现椭圆形失稳模式,砂土地层表现为失稳区整体塌落,黏土地层中土体自拱顶至上分块逐渐掉落;黏土-砂土复合地层破坏区是否发展至地表和最终失稳模式与上层黏土厚度有关,黏土地层较厚时失稳模式接近于均质黏土地层,较薄时地层破坏区更易发展至地表,且呈现U型失稳模式;砂土-黏土复合地层上部地层厚度对破坏区是否发展至地表和最终失稳模式的影响较小,下部黏土地层破坏发展与均质黏土地层接近,上部砂土地层主要呈现整体失稳破坏的特征.A novel index named particle relative motion(RPM)is proposed to characterize the progressive failure behavior of materials.The calculation formula of RPM is deriveed by considering both translational and rotational movements of particles.Based on the PFC2D platform,the calculation of RPM field is realized,then a new analysis method for granular material failure is established.Further,the validity of this method in describing the failure process of geotechnical materials is verified by the results of the trapdoor test.Finally,the progressive failure processes and instability modes of different strata induced by tunnelling are analyzed by establishing PFC models taking a tunnel in the Beijing Metro Line 12 as the engineering background.In both homogeneous sand and clay strata,the collapsed areas are presented in an elliptical shape,but it exhibits overal collapse in the sand stratum and gradually falling with blocks from the tunnel crown to surface in the clay stratum.For clay-sand composite strata,the thickness of the upper clay layer is a key factor in determining whether the failure zone develops to the surface and the ultimate instability mode.When the clay layer is thicker,the instability mode is similar to that of a homogeneous clay layer,while when it is thinner,the collapse zone is more likely to develop to the surface and presents a U-shaped instability mode.For sand-clay composite strata,the thickness of the upper strata has a relatively small impact on whether the collapse zone develops to the surface and the final instability mode.The development of collapse in the lower clay layer is similar to that in the homogeneous clay stratum,and the upper sand layer mainly exhibits overall collapse.

关 键 词：隧道开挖 复合地层 失稳模式 土拱效应 颗粒相对运动(RPM) 变形局部化 离散元 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]