隧道盾构法施工参数对地表沉降的影响分析

Analysis of Shield Tunneling Parameters Influence on Ground Settlement

隧道盾构法施工地表沉降规律是反映施工安全性的最主要体现,以京滨铁路滨海机场隧道为工程背景,通过理论分析和数值模拟手段重点分析盾构法施工参数中不同密封舱压力和地层损失率对地表沉降的影响规律。研究结果表明:1) 随着密封舱内压力增大,掌子面后方累计地表沉降值逐渐减小,而掌子面前方地表会由沉降变为隆起,对于天津地区黏土地层,建议密封舱内压力取平衡土压或略高于平衡土压(0.15 MPa~0.20 MPa);2) 地表沉降最大值随地层损失率增加呈线性增加,地层损失率由0.5%升到3%时,地表沉降值由5.04 mm增大到31.50 mm,建议施工过程中地层损失率控制在0.5%以下。

The surface settlement law of shield tunneling is the most important reflection of construction safety. Taking Binhai Airport Tunnel of Beijing-Binhai Railway as the engineering background, and this paper focuses on the influence of different seal chamber pressure and formation loss rate in shield construction parameters on surface settlement through theoretical analysis and numerical simulation. The results show that: 1) With the increase of the pressure in the sealed chamber, the accumulated surface settlement behind the heading face gradually decreases, while the surface in front of the tunnel face will change from settlement to uplift. For the clay stratum in Tianjin area, it is suggested that the pressure in the chamber should be balanced earth pressure or slightly higher than the equilibrium earth pressure (0.15 MPa~0.20 MPa);2) The maximum value of ground settlement increases linearly with the increase of formation loss rate. When the formation loss rate increases from 0.5% to 3%, the surface settlement value increases from 5.04 mm to 31.50 mm. And it is suggested that the formation loss rate should be controlled below 0.5%.