富水粗砂层地铁暗挖区间地表沉降模拟分析

A Simulation Analysis of the Ground Settlement in the Tunneled Section of a Coarse Sand Stratum Abundant with Water

为揭示富水砂质围岩地铁施工对周围环境的影响,采用应力释放法并考虑流固耦合模拟了某富水粗砂层地铁暗挖区间开挖及渗水引起的地表沉降过程。模拟结果表明:地下水向洞内渗漏的初期引起地表非均匀沉降,在后期影响范围内地表的沉降增量相差不大,表现为整体沉降;开挖面封闭后,孔隙水向低水头区渗流导致拱顶上方地表略有隆起;应力释放与渗水引起的地表沉降最大值出现位置相距约2.5m;最大地表累计沉降10.70mm。表明施工对周围环境影响有限。

To reveal the influence of the subway construction in rich-water coarse sand stratum on the surrounding environment,the stress-releasing method is applied to simulating the excavation-and-seepage-caused ground settling process of the tunneled section for the metro in the rich-water coarse sand stratum,with the fluid-solid coupling taken into consideration in the meantime.The simulated result shows that 1）uneven settlement appears in the earlier period when the groundwater seeps into the tunnel of the metro,while the ground surface settlement increment in the influenced area shows little difference in the later period,with the ground surface settling as a whole;2）After the closure of the excavated face,the groundwater seepage into the lower-water-headed area results in somewhat upheaval of the ground surface right above the vault.3）the distance between the stress-releasing-caused ground surface settlement location and the greatest value of the seepage-caused ground surface settlement is about 2.5m;4）the maximum accumulated ground surface settlement is 10.70 mm.It is proved that the effect of the construction on the surrounding environment is limited and acceptable.