北京地铁车站洞桩法施工变形规律分析

Analysis of Deformation Laws in Construction of Beijing Metro Stations by Hole Pile Method

以北京某地铁线单层导洞洞桩法(PBA工法)车站为工程背景,运用FLAC3D有限差分数值模拟软件对车站PBA工法施工过程中地表竖向及水平位移、底部隆起、边桩水平位移进行模拟分析,并将结果与监测数据进行对比,结果表明:数值模拟结果和实测数据略有差异,但变形趋势相同,即在整个车站施工过程中,地表沉降及底部隆起均呈现对称趋势,但地表最大沉降点始终发生在中线位置,而最大隆起位置从中导洞逐渐移动到车站中线上;地表水平位移呈现以车站中线为对称轴的反对称图形,两侧土体向中线方向移动;两侧边桩向结构内部移动呈现“凸”形。

This paper takes the single-layer pilot tunnel pile method(PBA method)station of a Beijing subway line as the engineering background,and uses FLAC3D finite difference numerical simulation software to calculate the vertical and horizontal displacements of the ground surface,the bottom uplift,and the horizontal displacement of the side piles during the construction of the station by the PBA method,performs simulation analysis and compares the results with the monitoring data.The results show that the numerical simulation results are slightly different from the measured data,but the deformation trend is the same,that is,during the entire station construction process,the surface settlement and bottom uplift show a symmetrical trend,but the maximum settlement point of the ground always occurs at the center line,and the maximum uplift position gradually moves from the pilot hole to the center line of the station;the horizontal displacement of the ground surface presents an anti-symmetric figure with the center line of the station as the axis of symmetry,and the soil on both sides moves toward the center line;The movement of the side piles into the structure presents a“convex”shape.