防灾减灾工程学报2023，Vol.43Issue(6)：1454-1462,9.DOI:10.13409/j.cnki.jdpme.20221009002
上覆富水砂层地铁隧道掌子面变形特征数值试验研究
Numerical Experimental Study on Deformation Characteristics of Metro Tunnel Excavation Surface with Overlying Water-rich Sand Layer
摘要
Abstract
In order to study the deformation characteristics of subway tunnel under the unfavorable geo-logical conditions of overlying water-rich sand layer,a typical tunnel,in dynamic water-rich and weak-ened sand stratum of Qingdao metro No.2 line(the Pi-Miao section),was taken as a research model,FLAC3D numerical simulation software is used to study the displacement of tunnel excavation surface and the variation characteristics of plastic zone under different thickness of water-rich sand layer and water-repellent layer.The results show that the larger the thickness of the water-repellent layer and the smaller the thickness of flowing sand layer,the smaller the deformation of the excavation surface will be.The thickness of waterproof layer is the main control factor affecting whether water and sand inrush occurs on the excavation face.In the process of excavation,maintain a safe distance between the sand layer and the tunnel.Once it is less than 3 m,tunneling should be stopped immediately and corresponding advance reinforcement measures should be taken.Taking the critical condition as the re-search object,the stress and displacement deformation law of tunnel's arch,waist,and face during ex-cavation were analyzed,and the displacement release coefficient and stress release rate were intro-duced to reveal the relationship between surrounding rock and the excavation face during tunnel exca-vation.By further fitting the prediction equation for the instability and failure of the excavation face,an important conclusion was drawn:that the inflection point of deformation release rate of excavation face is prior to the radial deformation of the surrounding rock in the same section and occurs before the excavation reaches the target section.Therefore,the deformation of the excavation face should be re-garded as the primary sensitive monitoring index during the actual tunnel excavation.The research re-sults can provide some theoretical guidance for the stability of the tunnel excavation face and the selec-tion of pre-reinforcement timing under the unfavorable geological conditions.关键词
富水砂层/数值试验/隧道掌子面/变形特征Key words
quicksand stratum/numerical experiment/tunnel excavation surface/deformation charac-teristics分类
建筑与水利引用本文复制引用
张红军,张太平,王奎峰,许艳,王薇,王强,张龚..上覆富水砂层地铁隧道掌子面变形特征数值试验研究[J].防灾减灾工程学报,2023,43(6):1454-1462,9.基金项目
山东省自然科学基金项目(ZR2019BEE021)资助 （ZR2019BEE021）
