粉细砂地层盾构施工地层变形规律分析

摘要

In bypassing water-rich silty fine sand stratum,a section of the No.1 Metro Line in Suzhou faced the challenges of water inflow,sand gushing and instability in evacuation face. Drawing on the data collected on site,the paper analyzed stratum deformation and concluded the following. T he Peck equation can be applied in depicting the ground deformation,with the ground loss ratio 0. 37% ~ 0. 66% and trough with parameter 0. 30 ~ 0. 38. T he relation between embedment depth and the settlement of the arch crown was found to be a linear one,with every 1 m drop in embedment depth bringing about 0. 89 mm decrease in average settlement. Stratum deformation has dispersim effect in the upword propagation process,during which the decline of maximum settlement promised more extensive effect. Different embedment depth and ground environment,the stratum deformation was still in accordance with Peck equation. W ith increase of embedment depth,ground loss ratio had not obvions change,but trough width parameter had the trend of increase. T he relation between the two was roughly a linear one.%苏州市轨道交通1号线一区间穿越富水粉细砂地层，盾构施工面临涌水、涌砂、开挖面失稳的风险。本文结合现场监测数据，对地层变形进行分析，得到以下规律：地表变形可用经典的 Peck 公式描述，拟合得到的地层损失率为0.37%～0.66%，沉降槽宽度系数为0.30～0.38；隧道拱顶上方地层埋深与沉降值变化总体呈线性关系，埋深每减小1 m，平均沉降减小0.89 mm；地层变形在向上传播过程中有扩散效应，最大沉降值减小而影响范围增大；不同埋深、不同地层环境下，地层变形仍符合 Peck 公式；随着埋深的增加，地层损失率没有明显变化，而沉降槽宽度系数呈逐渐增大的趋势；埋深与地表沉降槽宽度系数近似呈线性关系。