盾构下穿高铁路基沉降控制标准及控制措施分析

Settlement Control Standard and Control Measures for Shield Tunneling under a High-speed Railway Subgrade

为研究盾构隧道下穿高铁路基的沉降控制措施及其效果,以西安地铁1号线三期工程盾构下穿徐兰高铁段工程为背景,通过对现行规范及既有类似工程案例的分析、结合既有无砟轨道的现状,确定了本工程隧道下穿高铁无砟轨道路基的控制标准,并以此选定了盾构隧道下穿高铁路基的盾构、加固以及辅助控制变形措施,依据施工方案并结合工程实际情况,理论分析了影响分区的判别准则及判别阈值,进而划分了铁路路基受到不同影响的分区,通过数值模拟的方法分析拟定施工方案的实施效果。结果表明:采用盾构下穿高铁路基避开CFG桩(水泥粉煤灰碎石桩)且进行地面袖阀管注浆加固的方案能够满足工程要求,道床的最大竖向位移为4.716 mm,最大水平位移仅为0.301 mm;CFG桩的最大竖向位移为11.93 mm。

To study the settlement control measures and effects of a shield tunnel passing through a high-speed railway foundation from below,taking the phaseⅢproject of the Xi’an Metro Line 1-Shield Crossing Xulan high-speed railway as the background,the current specifications and similar cases of existing projects,as well as the current situation of existing ballastless tracks are analyzed to,determine the control standards for the tunnel to pass through the subgrade of the high-speed rail ballastless track from below measures such as shield tunneling reinforcement and auxiliary deformation control for the shield tunnel are formulated to pass through the high-speed railway foundation.According to the construction plan and the actual situation of the project,the criterion and threshold of the influence zone are theoretically analyzed,the zones affected by different railway subgrades are divided,and the implementation effect of the proposed construction plan is analyzed through numerical simulations.The results show that the scheme of avoiding CFG(Cement Fly-ash Gravel)piles and grouting reinforcement with a sleeve valve pipe on the ground for the shield tunnel crossing the high-speed railway foundation from below can satisfy the engineering requirements.The maximum vertical displacement of the track bed was 4.716 mm,maximum horizontal displacement was only 0.301 mm,and maximum vertical displacement of the CFG pile was 11.93 mm.