富水砂层土压平衡式盾构螺旋输送机喷涌风险评价方法研究
曹铁军1曹阳2孟世强3蒋沛峰1朱儒3朱君4曹占林4
Blowout Risk Assessment Method of Screw Conveyor in Earth Pressure Balance Shield Tunneling through Water-bearing Sand Layers
CAO Tiejun1CAO Yang2MENG Shiqiang3JIANG Peifeng1ZHU Ru3ZHU Jun4CAO Zhanlin4
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作者信息:1.中国铁建股份有限公司南京地铁9号线一期工程施工总承包， 210019， 南京
2.南京地铁集团有限公司，210008， 南京
3.中铁十一局集团有限公司， 200126， 上海
4.同济大学交通学院， 201804， 上海
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Affiliation:1.Nanjing Metro Line 9 Phase Ⅰ Construction Contract, China Railway Construction Corporation Limited, 210019, Nanjing, China
2.Nanjing Metro Group Co., Ltd., 210008, Nanjing, China
3.China Railway 11th Bureau Group Co., Ltd., 200126, Shanghai, China
4.College of Transportation, Tongji University, 201804, Shanghai, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.20230523
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中图分类号/CLCN:U455.43
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栏目/Col:土建工程
摘要:
［目的］盾构在富水砂层中施工时，因地下水丰富、土体渗透性大，螺旋输送机极易发生喷涌,若控制措施不当，可能引发施工安全事故。因此，需对土压平衡式盾构在富水砂层中施工时螺旋输送机喷涌风险评价方法进行研究。［方法］建立了土仓-螺旋输送机压力梯度模型，将土压平衡式盾构的水流通道简化为二维平面问题；依据达西定律，认为土仓内的流体通过孔隙介质进行二维达西流动，而螺旋输送机内的流体则进行一维达西流动；结合边界条件，采用有限差分-解析解联合方法计算了土仓中一定水压条件下螺旋输送机出口处的水头-流量曲线，提出了螺旋输送机喷涌风险划分方法。根据螺旋输送机出口水流高度和涌水量，定义了4个临界状态和5个风险区域，分别为一级风险区、二级风险区、三级风险区、四级风险区和安全区，建立了螺旋输送机喷涌风险划分标准和喷涌风险分区分级方法。以南京地铁9号线穿越长江漫滩地区绿博园站—滨江公园站盾构区间为例，对该区间进行了螺旋输送机喷涌风险等级划分，形成了喷涌风险单元链。［结果及结论］该盾构区间存在6条螺旋输送机喷涌风险等级的施工单元链，包含3个风险等级，其中一级风险等级区段长约408 m，二级风险等级区段长约463 m，无喷涌风险等级区段长约241 m，占比分别为36.69%、41.64%和21.67%。在该区间施工时，螺旋输送机喷涌风险高，施工距离长，需要针对不同风险等级采用不同防喷涌措施，从而保证盾构施工安全高效。
Abstracts:
［Objective］ During shield tunneling in water-bearing sand layers, due to abundant groundwater and high soil permeability, screw conveyors are highly prone to blowout incidents. If control measures are inadequate, serious construction safety accidents may occur. Therefore, it is essential to study a blowout risk assessment method for screw conveyors in EPB (earth pressure balance) shield tunneling through water-bearing sandy strata. ［Method］ A pressure gradient model of the excavation chamber and screw conveyor is established, simplifying the water flow channel in EPB shield to a two-dimensional plane problem. Based on Darcy′s law, fluid in the pressure chamber is considered to undergo two-dimensional Darcy flow through a porous medium, while the fluid in the screw conveyor will undergo one-dimensional Darcy flow. By incorporating boundary conditions, a combined finite difference-analytical solution method is applied to calculate the head-discharge curve at the screw conveyor outlet under specified water pressure conditions in the soil chamber. A blowout risk classification method for screw conveyors is proposed. Four critical states and five risk zones are defined according to water height and inflow volume at the screw conveyor outlet, they are classified as Level Ⅰ, Ⅱ, Ⅲ, and Ⅳ risk zones, and a safety zone respectively. A classification standard and zoning-grading method for blowout risk of screw conveyors is established. Taking the shield interval between Lyuboyuan Station and Binjiang Park Station on Nanjing Metro Line 9 as an example, which crosses the Yangtze River floodplain area, a screw conveyor blowout risk level classification is carried out on the interval, forming a risk unit chain for blowout assessment. ［Result & Conclusion］ In this shield interval, six construction unit chains with varying screw conveyor blowout risk levels are identified, covering three risk levels. Among which, the segment of Level I risk measures approximately 408 m, Level II about 463 m, and the no-risk zone about 241 m, accounting for 36.69%, 41.64%, and 21.67% of the total length, respectively. Given the high blowout risk and long construction distance during the interval construction, differentiated anti-blowout measures should be adopted for different risk levels to ensure safe and efficient shield tunneling.
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