含软弱夹层隧道围岩渗流稳定性离散元分析  

Discrete Element Analysis of Seepage Stability of Tunnel Surrounding Rock with Weak Interlayer

作　　者：董琪 王媛 陈宇 DONG Qi;WANG Yuan;CHEN Yu(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210024,China;National Key Laboratory of Water Disaster Prevention,Nanjing 210024,China;College of Civil and Transportation Engineering,Hohai University,Nanjing 210024,China)

机构地区：[1]河海大学水利水电学院,南京210024 [2]水灾害防御全国重点实验室,南京210024 [3]河海大学土木与交通学院,南京210024

出　　处：《河南科学》2024年第7期1011-1018,共8页Henan Science

基　　金：国家自然科学基金(52309128);江苏省卓越博士后计划(2022ZB170)。

摘　　要：软弱夹层和地下水渗流作用均对隧道开挖时的围岩稳定性有重要影响.依托蒙华铁路中条山隧道工程,搭建了PFC-FLAC流固耦合模拟平台,通过与均质围岩隧道位移理论解作对比,验证了该平台模拟渗流作用下隧道开挖时围岩力学响应的可靠性.在此基础上,对地下水渗流作用下含软弱夹层隧道围岩的失稳破坏过程进行了非连续数值模拟,深入分析了隧道开挖后围岩位移场、应力场、裂纹动态发展规律及能量场演化规律,研究了复杂水文地质条件下隧道围岩失稳破坏机理.结果表明:隧道开挖后的围岩破坏形式表现为顶部软弱夹层区域出现大量张拉和剪切裂纹,软弱夹层和少部分砾岩逐渐剥落破坏.洞周围岩迅速形成一个带有缺口的接触力链环,环内围岩应力卸载明显,洞周围岩的应变能密度差值均呈现先减小后回升的规律.The stability of surrounding rock during tunnel excavation is significantly influenced by the presence of weak interlayer and groundwater seepage.Based on the Zhongtiaoshan tunnel project of Menghua Railway,a PFC-FLAC fluid-solid coupled simulation platform is established,and its reliability in simulating the mechanical response of surrounding rock during tunnel excavation under seepage conditions is validated.On this basis,the discontinuous numerical simulation of the instability and failure processes of surrounding rock of the tunnel with weak interlayer under the influence of groundwater seepage is conducted.The displacement field,stress field,dynamic crack development law and energy field evolution law of the surrounding rock after tunnel excavation are deeply analyzed.Moreover,the instability and failure mechanism of the surrounding rock of the tunnel under complex hydrogeological conditions is investigated.Research findings indicate that the failure mode of the surrounding rock mass after tunnel excavation is that a large number of tension and shear cracks appear in the top weak interlayer zone,and the weak interlayer and a small portion of gravel gradually peel off.The rock around the tunnel quickly forms a contact force chain ring with a notched structure.Stress unloading of the surrounding rock in the ring is obvious,and the difference value of strain energy density of the rock around the tunnel decreases first and then rises.

关 键 词：隧道工程 渗流作用 软弱夹层 离散元 围岩稳定性 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]