盾构下穿胶济铁路路基沉降规律与变形控制

以青岛地铁2号线盾构隧道下穿既有胶济铁路为背景，采用三维数值模拟方法研究胶济铁路路基的沉降规律和变形控制。首先针对工程存在破碎带的情况，分析盾构穿越破碎带对铁路路基沉降的影响。然后考虑青岛上软下硬地层的特点，分别采用上部土层注浆加固和下部岩层全断面帷幕注浆加固方案，研究不同加固方案对盾构下穿既有铁路路基的变形控制效果。研究结果表明: 盾构穿越破碎带区段时铁路路基沉降偏大，施工存在安全风险，影响胶济铁路的安全运营；地层加固后路基的沉降相较于地层未进行加固有明显的降低，上部土层注浆加固使路基沉降值降低了约40%，全断面帷幕注浆加固使路基沉降值降低了约65%，同时下部岩层加固相较于上部土层注浆加固对路基变形控制更加显著；地层加固后TBM下穿施工对铁路路基的影响减小，能够确保胶济铁路的正常运营。

Settlement Law and Deformation Control of Subgrade When Shield Underneath Jiaoji Railway

Taking the shield tunnel of Qingdao Metro Line 2 undercrossing the existing Jiaoji Railway as the background, the settlement law and deformation control of Jiaoji Railway subgrade were studied based on three-dimensional numerical simulation method. Firstly, in view of the existence of crushing zone in the project, the influence of shield crossing crushing zone on railway subgrade settlement was studied. Then according to the characteristics of the upper soft and lower hard strata in Qingdao, the upper soil grouting reinforcement scheme and the lower rock curtain grouting reinforcement scheme were used to study the deformation control effect of shield undercrossing the existing railway subgrade. The results show that the settlement of railway subgrade is too large when shield passes through the broken zone section, and there are safety risks in construction, which affects the safe operation of Jiaoji Railway. The settlement of the roadbed after stratum reinforcement is significantly lower than that of the stratum without reinforcement. The upper soil grouting reinforcement reduces the settlement value of the roadbed by about 40 %, and the whole section curtain grouting reinforcement reduces the settlement value of the roadbed by about 65 %. At the same time, the lower rock reinforcement is more significant than the upper soil grouting reinforcement. The influence of shield tunneling on railway subgrade reduces after stratum reinforcement, which can ensure the normal operation of Jiaoji railway.