大直径双线盾构隧道施工期地表沉降监测分析

Analysis of Surface Settlement Monitoring during the Construction Period of a Large-Diameter Double-Line Shield Tunnel

摘要: 本文针对大直径土压平衡盾构施工期地表沉降进行监测及分析。依托南沙至珠海城际某段的盾构地铁项目，通过现场监测及研究分析，对盾构施工期地表沉降展开研究，得出结论：1) 先发左线隧道通过监测横断面后，横向沉降折线呈类似高斯曲线，地表沉降的最大值点位于左线隧道轴线上方地表土体。2) 后发右线通过监测横断面后，地表继续沉降，横向沉降折线类似一个标准高斯曲线右侧叠加一个不完整的高斯曲线，最大值点右移，位于左线隧道轴线与双线隧道中轴线间的上方地表。3) 双线隧道通过区间后，横向沉降近似为两个高斯拟合曲线叠加，且沉降折线整体不对称，最大值点位于双线隧道中轴线与右线隧道轴线间的上方地表。4) 纵向地表沉降监测中，沉降折线总体呈现随距离增加斜率逐渐降低的趋势。5) 地表沉降的大小与隧道上覆土厚度呈负相关，与土层刚度也呈负相关。

Abstract: This paper monitors and analyzes surface settlement during the construction period of large-diameter earth pressure balance shield tunneling. Based on a shield tunnel metro project along a section of the Nansha-Zhuhai Intercity Railway, this study conducted on-site monitoring and research analysis to investigate ground settlement during shield construction. The conclusions drawn are as follows: 1) After monitoring the cross-section of the left-line tunnel, the lateral settlement curve resembles a Gaussian curve, with the maximum surface settlement point located above the left-line tunnel axis on the surface soil. 2) After the right-line tunnel was constructed, the ground surface continued to settle. The lateral settlement curve resembled a standard Gaussian curve with an incomplete Gaussian curve superimposed on its right side. The maximum value point shifted to the right and was located above the ground surface between the axis of the left-line tunnel and the central axis of the double-line tunnel. 3) After the double-track tunnel passes through the section, the lateral settlement is approximately the superposition of two Gaussian fitted curves, and the settlement curve is overall asymmetric, with the maximum value point located above the ground surface between the centerline of the double-track tunnel and the axis of the right-line tunnel. 4) In longitudinal ground surface settlement monitoring, the settlement curve generally shows a trend of decreasing slope with increasing distance. 5) The magnitude of ground subsidence is negatively correlated with the thickness of the overburden above the tunnel and also negatively correlated with the stiffness of the soil layer.