盾构隧道下穿对既有高铁桥梁的影响及其加固方案
耿大新谭成王宁
Impact of Shield Tunnel Underpassing Existing Highspeed Railway Bridge and Its Reinforcement Scheme
GENG DaxinTAN ChengWANG Ning
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作者信息:华东交通大学土木建筑学院， 330013， 南昌
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Affiliation:School of Civil Engineering and Architecture, East China Jiaotong University, 330013, Nanchang, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2023.08.006
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中图分类号/CLCN:U442.55
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栏目/Col:研究报告
摘要:
目的：盾构隧道掘进会引起周围既有高架桥梁整体结构的不均匀沉降，进而影响其正常使用功能和列车运行安全。对此，以南昌市轨道交通4号线一期工程某区间隧道为背景，分析盾构隧道先后下穿对既有高速铁路桥梁的影响及加固方案分析。方法：运用Midas GTS软件模拟盾构隧道先后下穿高速铁路桥梁的过程。分析高铁桥梁墩台顶部的位移及沉降的发展规律，以及加固前后墩台顶部的变形。结果及结论：盾构掘进对墩台顶沉降影响最大，墩台顶最大沉降约为340 mm，最大纵向位移约为250 mm；对横向变形影响最小，最大横向位移约为100 mm，且影响主要在初掘进阶段；盾构引起的高铁桥梁墩台顶变形随着后期管片安装和注浆有所减小；采取隔离桩+注浆加固措施后，桥墩台顶部产生的最大沉降约为154 mm，最大沉降差为034 mm，最大纵向位移为141 mm；最大墩顶沉降能满足高铁桥梁墩顶沉降的控制标准(300 mm)要求，且留有一定的变形裕量，较安全。采用注浆与隔离桩加固措施效果良好，安全可行。
Abstracts:
Objective: Shield tunnel excavation causes the overall structure uneven settlement of existing highspeed railway bridges in the surrounding area, thereby affecting their normal functionality and operational safety of train. In this context, based on an interval tunnel of Nanchang Rail Transit Line 4 phase I project, the impact of shield tunnel underpassing existing highspeed railway bridge and the reinforcement schemes are analyzed.Method: The process of shield tunnel underpassing existing highspeed railway bridges is simulated using Midas GTS software. The development law of displacement and settlement on the top of highspeed railway bridge piers and abutments are analyzed, as well as the deformation before and after reinforcement.Result & Conclusion: Shield tunneling has the greatest impact on the settlement of bridge piers and abutments, with a maximum settlement of approximately 3.40 mm and a maximum longitudinal displacement of about 2.50 mm. The impact on lateral deformation is minimal, with a maximum lateral displacement of about 1.00 mm, mainly occurring in the initial excavation stage. The deformation of highspeed railway piers caused by shield tunneling decreases with the subsequent installation of tunnel segments and grouting. After implementing isolation piles + grouting reinforcement measures, the maximum settlement of bridge pier tops is approximately 1.54 mm, with a maximum settlement difference of 0.34 mm and a maximum longitudinal displacement of 1.41 mm. The maximum settlement of the pier and abutment tops meets the control standard requirement (3.00 mm) for highspeed railway bridge pier settlement and allows for a certain deformation margin, being relatively safe. The reinforcement measures of grouting and isolation piles perform well, being safe and feasible.
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