新建城际铁路盾构小净距下穿既有地铁隧道沉降控制研究
葛佳佳1董卫国1江苏洋2李海波3张会坚1
Settlement Control of New Intercity Railway Shield Urderpassing Existing Metro Tunnel at Small Clearance
GE JiajiaDONG WeiguoJIANG SuyangLI HaiboZHANG Huijian
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作者信息:1.浙江杭海城际铁路有限公司, 314400， 海宁
2.河海大学土木与交通学院， 210024， 南京
3.中国中铁四局集团第二工程有限公司， 215131， 苏州
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Affiliation:Zhejiang Hanghai Intercity Railway Co., Ltd., 314400, Haining, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2023.08.009
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中图分类号/CLCN:P642.26∶U455
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栏目/Col:研究报告
摘要:
目的：新建线路盾构近距离下穿既有线隧道时，不仅会引起地层沉降和变形，还会引起既有线隧道的不均匀沉降、开裂，甚至破坏，因此需针对该类工程，研究沉降控制措施，以减小施工风险，确保既有线的安全运营。方法：依托杭海城际铁路下穿杭州地铁1号线工程，采用数值模拟方法进行分析。介绍了工程基本概况及施工风险点；建立了计算模型，确定了模拟数值计算过程，并对不同施工工况下的地面沉降计算结果进行了分析；结合盾构掘进试验段施工参数及实施效果，对下穿段施工控制参数进行了合理优化，并提出了盾构下穿既有线隧道的沉降控制措施。结果及结论：①新建线路盾构下穿既有线隧道，引起既有线隧道最大沉降约为地面最大沉降值的1.81倍。②新建线路盾构下穿既有线隧道施工过程中引起沉降较大的时段为：新建盾构刀盘从既有线左右线隧道中部下方穿越至既有线右线隧道下方，新建线路盾构刀盘离开既有线右线隧道后2 d（d为新建线路盾构隧道外径）位置处至施工结束。③盾构下穿过程中，选用注浆量为5.7 m3/环、注浆压力为0.3~0.4 MPa、土舱压力为260~270 kPa、掘进速度为2.5~3 cm/min、排土量为57~63 m3/环；每掘进2环进行一次二次注浆，并且对沉降较大区域每环注入0.3~0.5 m3克泥效浆液。现场监测结果表明：既有线隧道最大沉降约为地面最大沉降的1.73倍，与模拟数值计算结果相近。
Abstracts:
Objective: When a new railway line constructed using shield tunnel underpassing existing tunnel in proximity, it can cause land subsidence, stratum deformation, uneven settlement, cracking, and even damage to the existing tunnels. Therefore, it is necessary to study settlement control measures for such projects to minimize construction risks and ensure the safe operation of existing tunnels. Method: Taking HangzhouHaining Intercity Railway underpassing Hangzhou Metro Line 1 as example, numerical simulation methods are used for analysis. The basic project overview and construction risk points are introduced. A computational model is established, the numerical simulation process is determined, and the calculated results of land subsidence under different construction working conditions are analyzed. Based on the parameters and implementation effects of the shield tunnel test section, the control parameters for the underpassing section are reasonably optimized, and the settlement control measures for shield tunnel underpassing existing metro tunnel are proposed. Result & Conclusion: (1) New railway line shield tunnel underpassing existing metro tunnel causes maximum settlement in the existing tunnels to be approximately 1.81 times the maximum land subsidence. (2) The periods of significant settlement during the above underpassing process are as follows: when the shield cutterhead of the new tunnel passes from below existing line left/right line tunnel middle part to below existing tunnel right line tunnel, and the new line shield cutterhead leaves the position 2d (d is the outer diameter of the new line shield tunnel) away from existing line right line tunnel until the end of construction. (3) During shield underpassing process, 5.7 m3/ring grouting volume, 0.30.4 MPa grouting pressure, 260270 kPa soil chamber pressure, 2.53 cm/min excavation speed, 5763 m3/ring dumping volume. Secondary grouting is implemented for excavation of every 2 rings and 0.30.5 m3/ring gram mud injection at each ring in areas with larger settlement. Fieldmonitored results show that existing line tunnel maximum settlement is about 1.73 times of land maximum subsidence, similar to the simulation calculation results.
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