武汉地铁2号线盾构施工对地表沉降影响分析

Analysis on Influence of Shield Construction to Ground-surface Settlement in Wuhan Subway Line 2

对武汉地铁2号线盾构掘进施工过程中地表沉降监测数据统计,并根据Peck理论进行拟合对比分析,得到盾构施工引起纵横断面地表沉降的特点:纵向上,盾构机切口前30m以内和后50m以内为影响区域,其中又以切口后50m为显著影响区,盾构通过该区域产生的沉降占总沉降量的80%～90%,盾构对某断面上影响范围在沿盾构中心轴线向左右两侧延伸10～18m;对武汉粉质黏土夹粉土粉砂层,盾构掘进引起的地表沉降数据累计变化控制指标宜为-40mm,盾构机切口通过监测断面6～20m范围内单次平均变化速率控制值宜为-15mm/d。

The ground-surface settlement caused by shield construction is monitored in Wuhan Subway Line 2.Meanwhile the ground-surface settlement is simulated with Peck formula.Comparing the monitored and simulated settlement,some conclusions about the ground-surface settlement characteristics are obtained.In vertical cross-section,the impact region is 30m before shield incision and 50m after shield incision,and the later region is significantly impact region.The settlement amount caused by shield passing through is 80% ～ 90% of the total settlement.Shield impact region of a cross-section along the central axis of shield extends to the right and left sides within 10 ～ 18m.For the silty clay silt and silty sand layers in Wuhan,control index of cumulative ground-surface settlement caused by shield construction might be-40mm,and the control index about the average single settlement changing might be-15mm /d,within 6 ～ 20m of shield incision through the monitoring cross-section.