软土地区盾构隧道斜下穿多股铁路路基变形规律

Deformation Law of Shield Tunnel Oblique Under-passing Existing Multi-track Railway Subgrade in Soft Soil Area

目的:目前,地铁隧道穿越铁路路基的情况越来越多,但软土地区盾构隧道斜下穿既有运营铁路的研究相对较少,因此需分析该情况下的路基变形规律。方法:以绍兴轨道交通1号线大滩站—火车站站区间盾构隧道下穿杭甬铁路绍兴站站房及6股铁路股道工程为例开展研究。采用有限元法分析了盾构隧道掘进施工对杭甬铁路路基的变形影响,并基于实测数据对数值模拟结果进行了对比分析,充分验证了袖阀管注浆加固方案的有效性。结果及结论:有限元分析结果表明:未考虑盾构穿越区域地基加固的情况下,杭甬铁路路基顶面最大沉降值为13.12 mm,不满足沉降控制标准要求;当盾构穿越区域采用袖阀管注浆加固措施后,杭甬铁路路基顶面最大沉降值为8.20 mm,满足沉降控制标准要求,说明袖阀管注浆能够有效控制铁路路基沉降和轨道的不平顺。实测数据结果表明,盾构隧道下穿铁路施工期间的累计变形历程可分为路基隆起、路基快速沉降、路基平稳波动及后续沉降4个阶段,且前期隆起量大、后续变形相对较小,加固后的路基累计变形量能控制在10.00 mm以内。

Objective:Currently,with an increasing number of metro tunnels crossing existing railway subgrades,there is relatively insufficient study on shield tunnel oblique under-passing operating railways in soft soil area,thus it is necessary to investigate the deformation law of subgrades in such situations.Method:The interval shield tunnel engineering of Shaoxing Rail Transit Line 1 Datan Sta.to Railway Sta.under-passing Shaoxing Railway Station building and six railway tracks on Hangzhou–Ningbo Intercity Railway(Hang–Yong Railway)is taken as study case.Finite element method is employed to analyze the impact of shield tunnel excavation on the deformation of Hang–Yong Railway subgrade,and the comparative analysis of numerical simulation results based on field-measured data fully validates the effectiveness of the sleeve valve pipe grouting reinforcement scheme.Result&Conclusion:The finite element analysis results show that the maximum settlement value of Hang–Yong Railway subgrade surface reaches 13.12 mm when the foundation reinforcement in shield crossing area is not considered,failing to meet the settlement control standard.However,when sleeve valve pipe grouting reinforcement measure is implemented in the shield crossing area,the maximum settlement value of Hang–Yong Railway subgrade surface decreases to 8.20 mm,meeting the settlement control requirements.This demonstrates the effectiveness of this measure in controlling the railway subgrade settlement and track irregularity.The field-measured results show that the cumulative deformation process during the construction period of shield tunnel under-passing railway can be divided into four stages:subgrade heave,subgrade rapid settlement,subgrade stable fluctuation and subsequent settlement.The initial heave amount is large,while the subsequent deformation is relatively small.The cumulative deformation amount of the reinforced subgrade can be controlled within 10.00 mm.