浅层气地层对地铁隧道稳定性影响模型试验研究

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。

Model test research on influences of shallow gas stratum on stability of metro tunnel

Based on the distribution and occurrence characteristics of underground shallow gas in Hangzhou area, and combined with the Hangzhou Metro project, a model test system was established; and influences of gas release and re-accumulation of the shallow gassy soil on stabilities of metro tunnel were studied by the physical model test. Results show that gas actions of shallow gassy soil may cause the tunnel crossing gas reservoirs to generate additional deformations and internal forces; disturbances on relative deformation and internal force of the shield lining segments are little; but influences on the global deformation of tunnel structures are significant; values of the additional deformation and internal force caused in gas re-accumulation are much less than those in the former process of gas release. For the metro tunnel in regions buried shallow gas, global stability of tunnel structure should be as the control emphasis; and the gas in strata should be released under control before construction so as to reduce the later adverse effects on metro engineering.