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随着地下工程的建设日益增多,部分工程穿越含气地层,含气地层会对隧道的施工产生一定不良的影响。盾构在沼气地层掘进过程中,由于管片气密性不良造成沼气通过管片环缝进入隧道,引起管片的纵向变形。针对这一现象,建立管片环缝单点气体释放条件下的管片变形模型,并用数值模拟方法与理论结果进行对比验证。通过其变形公式,分析不同含气层厚度、不同初始气压条件对管片的变形及管片接缝张开量的影响,探讨管片损坏的地层条件。结果表明,对于含气层较薄(<1.5 m)、气体压力比较小(<150 kPa)的地层,隧道气密性不严导致气体泄漏进入隧道会导致管片下沉,但一般不会破坏管片的防水设施。当含气层厚度大或气体压力较大时,气体释放会引起比较大的管片变形,破坏管片的防水能力,导致地下水进入隧道,引起管片的进一步变形;地层扰动大时,地层土体随地下水进入隧道,会造成管片的严重损坏,以至于断裂。
With the construction of underground works increasing, some of the projects through gas-bearing strata, gas-bearing strata will have a certain adverse impact on the construction of the tunnel. In the biogas formation tunneling process, the biogas enters the tunnel through the girth of the pipe segment due to the airtightness of the pipe segment, causing the longitudinal deformation of the pipe segment. In response to this phenomenon, the deformation model of the tube under the single-point gas release condition was established and verified by numerical simulation and theoretical results. Through the deformation formula, the influence of different gas-bearing layer thickness and different initial pressure conditions on the deformation of the segment and the amount of joint opening is analyzed, and the formation conditions of the segment are discussed. The results show that for the strata with thin gas reservoirs (<1.5 m) and small gas pressure (<150 kPa), the gas tightness of the tunnel can lead to the sinking of gas into the tunnel, but it will not be damaged Pipes waterproofing facilities. When the thickness of gas-bearing layer is large or the pressure of gas is large, the release of gas will cause the deformation of larger pipe pieces and destroy the waterproofing ability of pipe pieces, resulting in groundwater entering the tunnel and causing further deformation of the pipe pieces. When the disturbance of formation is large, Body with the groundwater into the tunnel, will cause serious damage to the piece, so that rupture.