小半径曲线段盾构隧道掘进过程中地表变形规律

Ground Deformation Laws During Shield Tunneling Construction in Small Radius Curved Section

依托西安地铁2号线正阳大道—北客站区间小半径曲线段盾构隧道工程,通过现场监测和数值模拟,分析了考虑千斤顶不对称推力和曲线内侧土体超挖情况下,小半径曲线段盾构隧道掘进过程中地表变形规律及曲线半径对地表竖向位移的影响。研究结果表明:在盾构掘进过程中开挖面前方22.1 m附近地表轻微隆起;隧道纵向地表沉降最大值出现在开挖面后方12 m处;隧道横向地表沉降槽呈非对称分布,曲线内侧地表沉降大于曲线外侧,沉降槽中心线向曲线内侧偏离隧道轴线,偏移距离为5.5 m;曲线半径主要影响开挖面后方地表沉降,隧道纵向、横向地表沉降最大值均随曲线半径减小而增大,曲线半径超过350 m后,半径变化对开挖面后方地表沉降影响较小。

Based on the small radius curved tunnel section of metro line 2 Zhengyang Avenue-Beike station in Xi’an,considering asymmetric jack thrust and soil overbreak on the inner side of the curve,the ground deformation laws and the influence of curve radius on vertical displacement during the shield tunneling process in small radius curved section were analyzed through on-site monitoring and numerical simulation.The results show that the ground surface is slightly uplifted near 22.1 m ahead of the excavation face during shield tunneling process.The maximum longitudinal surface settlement appears at 12 m behind the excavation face.The transverse surface settlement trough was asymmetrically distributed,the surface settlement on the inner side of the curve is greater than that on the outside of the curve,and the centerline of the settlement trough deviates to the inner side of the curve with an offset of 5.5 m from the tunnel axis.The curve radius mainly affected the surface settlement behind the excavation face.The maximum values of longitudinal and transverse surface settlement increase with the decrease of curve radius.The radius change has little effect on the surface settlement behind the excavation face when the radius exceeds 350 m.