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根据杭州地区地下浅层气的分布规律和赋存特点,结合杭州地铁工程,设计了一套模型试验系统。借助物理模型试验,研究了浅层含气土层中气体释放和再回聚对地铁隧道受力稳定性的影响。试验结果表明,在含浅层气地层中穿过的地铁隧道,土中气体的释放和再回聚会使隧道产生附加变形与附加内力;气体变化过程对隧道管片截面相对变形和内力的影响较弱,而对隧道整体变形则具有显著影响;气体释放后的再回聚过程对隧道结构变形和内力的影响明显小于前期的气体释放过程。处于含浅层气地层区域的地铁隧道,应将隧道的整体稳定性作为控制重点,并且施工前,宜将地层中气体进行超前有控排放,以减弱后期给地铁工程带来的不利影响。
According to the distribution rules and occurrence characteristics of subsurface gas in Hangzhou area, combined with the Hangzhou subway project, a set of model test system was designed. With the help of physical model test, the influence of gas release and reagglomeration in shallow gas-bearing soil layer on the mechanical stability of subway tunnels was studied. The experimental results show that the release and re-assembly of gas in the earth can lead to additional deformation and additional internal forces in the subway tunnel passing through the shallow gas-bearing formations. The influence of gas change on the relative deformation and internal force of the tunnel segment Weak, but have a significant impact on the overall deformation of the tunnel; the effect of the re-aggregation process after release of gas on the deformation and internal force of the tunnel structure is significantly less than the previous gas release process. In metro tunnels with shallow gas formations, the overall stability of the tunnel should be the key point of control. Before the construction, the gas in the strata should be advanced and controlled to reduce the adverse impact on the subway project in the later stage.