软土地区盾构隧道掘进引起的地表沉降预测修订

在盾构隧道施工时, 地表沉降的Peck公式预测结果往往因地质条件的不同而与实测结果差异较大. 为此研究基于宁波轨道交通1号线地表沉降实测数据, 利用最小二乘和一元线性回归法, 确定了盾构隧道地表沉降槽宽度系数K和地层损失率Vl的取值范围, 并引入了地表最大沉降修订系数α和沉降槽宽度修订系数β对Peck公式进行修订. 结果表明: 宁波软土盾构隧道地表沉降槽宽度系数K范围为0.6~0.9, 建议取0.75, 地层损失率Vl范围为1%~3%, 建议取2%; 当修订系数α取1.2, β取0.8时, 能够获得比Peck公式更好的预测效果.

Modifications of Ground Surface Subsidence Prediction for Shield Tunnel Construction in Soft Soil

In the process of constructing shield tunnels, the result of prediction with Peck formula for ground surface subsidence shows great disagreement with the result measured under different geological conditions. Therefore, based on the measured data of ground surface subsidence in Ningbo Rail Transit Line 1, the range of trough width coefficient K of the ground surface settlement and the ground loss rate Vl of shield tunnel in soft soil of Ningbo are determined in this paper using the least square method and monadic linear regression. The coefficients of the maximum ground surface settlement α and the settlement trough width β are introduced and the Peck formula is modified. It is shown that the range of the surface settlement trough width coefficient K is between 0.6~0.9, and Vl is between 1%~3%, and 0.75 and 2% for K and Vl is recommended, respectively. When the value of α and β takes 1.2 and 0.8, respectively, a better prediction result can be obtained compared with the original Peck prediction formula