盾构开挖引起的地层位移空间分布预测模型

Spatial Distribution Prediction Method of Ground Displacement Induced by Shield Tunneling

研究目的:盾构施工引起地层位移是城市地铁建设中不可忽略的问题。目前,大多数沉降预测方法是针对地表的,缺乏对地层位移空间分布的具体研究。基于此,本文以北京地铁14号线为工程背景,采用数值分析手段研究地层内部沉降及其影响范围与地表的联系,提出一种基于地层位移沿横向和纵向分布公式相结合的空间分布预测方法,并与现场实测进行对比验证。研究结论:(1)盾构前后地层任意横剖面的地表沉降槽宽度系数与其最终值基本一致;(2)地表及地层内部沉降槽都呈现正态分布形式,随着埋深增加,沉降槽最大值呈现幂函数的非线性增长规律,沉降槽宽度系数呈现幂函数形式的非线性减小趋势;(3)任一点的地层位移与地表最终沉降值、沉降槽宽度系数、地层损失率等有关;(4)该研究成果可为类似地质条件盾构施工引起地层位移的空间预测提供理论依据。

Research purposes： The effect of shield tunnelling - induced displacement is really a concern that should be drawn attention in metro construction. Most prediction of settlement is focused on surface and rare study on spatial distribution prediction is carried out. Therefore, based on the engineering background of Line 14 in Beijing Subway, numerical simulation is adopted to investigate the relationship of the settlement and influence range between subsurface and surface, and a prediction method of spatial distribution for ground settlement on the basis of the combination of the transverse and longitudinal ground settlement is proposed and verified with field test.Research conclusions ： （ 1 ） Coefficients of surface settlement trough width of any cross section ahead of or behind the shield is generally equal to that of the final settlement trough. （2） The settlement troughs both in surface and subsurface reflect the normal distribution. With the increase of depth, the maximum of settlement shows a nonlinear increase of power function and the width coefficient of settlement trough reflects a nonlinear deerease of power function. （ 3 ） The ground settlement of any point is related to the maximum surface settlement value, coefficient of settlement trough width and volume loss. （4） The research results provide theoretical guidance for shield tunnelling- induced displacement in similar geological conditions.