双线盾构隧道施工稳定性分析

Analysis on construction stability of double-line shield tunnel

为研究双线盾构隧道先后开挖对结构稳定性以及两者相互作用的影响,本文以厦门市翔安行政中心站——浦边站为工程背景,采用有限元软件Midas-GTS建立模型,分析双线隧道先后开挖对盾构管片、箱涵结构以及地表沉降的影响,对比隧道加固前后箱涵结构的关键点沉降变化规律。研究结果表明:1)双线隧道开挖完成后,左右线隧道正上方处箱涵结构沉降最大,分别为6.74、6.14 mm,箱涵结构正下方处的隧道管片变形最小;2)箱涵结构限制了土体的竖向位移,使土体产生横向变形,导致开挖后沉降槽宽度增大至30 m,最终地表沉降呈现“U”形;3)在隧道下穿箱涵范围内对隧道进行环向注浆加固,可保证箱涵结构的稳定。本文成果可为今后双线盾构隧道施工提供一定借鉴。

In order to research the influence of successive excavation of double-line shield tunnel on structural stability and the interaction between the two,the finite element software Midas-GTS is used to establish a model based on Xiamen Xiang’an Administrative Center Station to Pubian Station,the effects of successive excavation of double-line tunnel on shield segments are analyzed,box culvert structure and surface settlement,and the settlement variation law of key points of box culvert structure are compared before and after tunnel reinforcement.The results show that:1)After the completion of the excavation of the double-line tunnel,the box culvert structure directly above the left and right line tunnel has the largest settlement,6.74 mm and 6.14 mm,respectively,and the tunnel segment deformation at the bottom of the box culvert structure is the smallest;2)The box culvert structure limits the vertical displacement of the soil and causes lateral deformation of the soil,resulting in the increase of the width of the settlement groove to 30 m after excavation,and the final surface settlement is“U”shaped;3)Ring grouting reinforcement of the tunnel within the scope of the tunnel through the box culvert can ensure the stability of the box culvert structure.The results can provide a certain references for the construction of a double-line shield tunnel in the future.