隧道施工引发粉土地面沉降模拟与分析

Simulation and Analysis of Silt Land Subsidence Caused by Tunnel Construction

为研究黄泛区粉土地层内开挖双线地铁隧道对地上及其周边地面沉降的影响,以某双线地铁隧道开挖工程为例,考虑地下水、隧道间距对地面沉降的影响,采用流固耦合数值方法和理论分析方法对隧道施工引起的地面沉降规律进行分析。将数值模拟数据与Peck公式进行反演计算,并考虑隧道间隔和埋深的影响提出修正Peck公式,再结合叠加原理建立适用于双线隧道开挖引起地面沉降的修正叠加公式。结果表明:隧道开挖扰动地层将引起超静孔隙水压力现象;数值模拟与理论计算得到隧道间隔为4 m时,地面沉降曲线呈现“V”型,隧道间隔为8 m、12 m时,则沉降曲线呈现“U”形;粉土内开挖双线地铁隧道,地面容易受到扰动且沉降量大,随着隧道间距的增加,隧道上方土体沉降量逐渐减小;基于修正Peck公式计算结果与数值模拟结果基本一致,相对误差在3%左右,表明该公式具有很好的实用性。研究可为粉土地区隧道及地下工程建设提供理论依据和技术支撑。

In order to study the influence of a twin-line underground tunnel excavation in the Yellow River flood area silt on the land subsidence above and around it,a twin-line underground tunnel excavation project is taken as an example,considering the influence of groundwater and tunnel spacing on the land subsidence,the fluid-structure coupling analysis and theoretical analysis methods in numerical simulation are used to analyze the land subsidence law caused by tunnel construction.The numerical simulation data and Peck formula were inverted,and the Peck formula was proposed considering the influence of tunnel spacing and buried depth.Combined with the superposition principle,the corrected superposition formula suitable for land subsidence caused by double-line tunnel excavation was established.The results show that tunneling disturbs the stratum and causes the phenomenon of excess pore water pressure.According to numerical simulation and theoretical calculation,when the tunnel interval is 4 m,the land subsidence curve presents a"V"shape,while when the tunnel interval is 8 m or 12 m,the land subsidence curve presents a"U"shape.When the twin-line tunnel is excavated in silt,the land is prone to disturbance and subsidence is large.With the increase of tunnel spacing,the subsidence of soil above the tunnel decreases gradually.The calculation results based on the modified Peck formula are in good agreement with the numerical simulation results,and the relative error is about 3%,indicating that the formula has good practicability.This study can provide theoretical basis and technical support for tunnel and underground engineering construction in silt area.