软弱土地层下双线隧道盾构施工引起的地表沉降及其敏感性分析

Under soft soil layer on surface settlement induced by double-track tunnel construction and its sensitivity analysis

盾构隧道开挖所造成的地表沉降受设计参数和施工参数的影响。为研究双线盾构设计和施工参数对地表沉降的影响规律,本研究依托杭州下沙路隧道工程,结合FLAC3D有限差分软件研究双线隧道设计间距、双线隧道开挖间隔、注浆模量和掌子面压力对地表沉降的影响,并对这四个参数进行敏感性分析。研究结果表明:在各研究参数临界值之下,地表最大沉降随着双线隧道设计间距比值d/D、双线隧道开挖间隔L、注浆模量E、掌子面压力σ的增加而减小,当超过各研究参数临界值时,提高该参数对控制地表沉降的效果有限;在盾构施工中,未开挖隧道应在已开挖隧道不影响其初始位置处土体变形时再开挖;在基准条件下,掌子面压力的敏感度因子最大,其次为双线隧道设计间距、双线隧道开挖间隔和注浆模量,注浆模量的影响可以忽略不计。

The ground settlement caused by shield tunnel excavation is affected by design parameters and construction parameters. In order to study the rules of shield design parameters and construction parameters on ground settlement, this paper relies on the Hangzhou Xiasha Road Tunnel Project and combined with FLAC3 D finite difference software to study the effect of double-line tunnel design spacing, double-line tunnel excavation spacing, grouting modulus and different face pressures on ground settlement and the sensitivity analysis of these four construction parameters. Research shows: Below the critical value of each research parameter, the maximum surface settlement decreases with the increase of design spacing ratio d/D, excavation spacing L, grouting modulus E and face pressure σ of double track tunnel, and when it exceeds the critical value of the research parameters, the effect of improving the parameters on controlling surface settlement is limited;In shield construction, the unexcavated tunnel should be excavated when the excavated tunnel does not affect the soil deformation at its initial position;under the reference conditions bottom, the sensitivity factor of face pressure is the largest, followed by the double-line tunnel design spacing, double-line tunnel excavation spacing, and the grouting modulus. The influence of grouting modulus is negligible.