高水位砾砂地层地下连续墙成槽施工技术研究  

Research on Slot Formation Technology for Diaphragm Wall in High Water Head Gravel-sand Stratum

作　　者：李永灿 Li Yongcan(China Railway 18th Bureau Group Co.,Ltd.,Tianjin 300300,China)

机构地区：[1]中国十八局集团有限公司,天津300300

出　　处：《市政技术》2025年第2期88-95,共8页Journal of Municipal Technology

摘　　要：呼和浩特地铁2号线一期工程呼和浩特站所处地层为圆砾与砾砂互层地层,围护结构采用地下连续墙,地下水位标高与墙顶标高一致,在开槽施工过程中槽壁失稳,采用三维抛物柱体破坏计算模型及流体动力学理论对失稳原因进行了分析,并对其施工参数优化进行了研究。研究结果表明:泥浆液面与地下水位高差、泥浆重度、破坏体宽度、地面荷载和抓斗操作速度均对槽壁稳定性安全系数有显著影响;假定破坏体高厚比不变时,槽壁稳定性安全系数随泥浆液面与地下水位高差的增大呈非线性增大趋势,随泥浆重度的增大呈线性增大趋势,且深层(6 m以上)的槽壁稳定性安全系数敏感性大于浅层(6 m以内);槽壁稳定性安全系数随破坏体宽度的增大呈非线性增大趋势,随地面荷载的增大呈非线性减小趋势,且深层(8 m以上)槽壁稳定性安全系数敏感性大于浅层(8 m以内)。此外,雷诺数随抓斗操作速度的增大而增大,随浆液密度的增大而减小。基于此提出了高水位下砾砂地层成槽施工的控制参数:泥浆液面与地下水位高差大于1.5 m,泥浆重度大于11.8 kN/m^(3),地面荷载小于356.5 kN,抓斗操作速度小于0.85 m/s,经现场施工验证可知取得了良好的施工效果,为类似工程提供了参考。Hohhot Station of Hohhot Metro Line 2 is in alternating layers of round gravel and sandy gravel with the retaining structure of diaphragm wall.The elevation of the groundwater level was consistent with the one of the wall top.Instability of groove wall occurred during the slotting construction process.A 3D parabolic column model and fluid dynamics theory was used to analyze the causes of instability and optimize construction parameters.Results in-dicate that several factors significantly impact the stability safety factor of the trench wall,namely the difference be-tween the slurry level and the groundwater level,slurry density,the width of the failure zone,surface load,and the speed of the grab operation;With a constant height-to-thickness ratio of the failure body,the stability safety factor increases nonlinearly with the difference between the slurry level and groundwater level and linearly with slurry den-sity;Furthermore,sensitivity in deeper layers(over 6 m)is greater than in shallow layers(within 6 m);The stability safety factor also increases nonlinearly with the failure body width and decreases nonlinearly with surface load,with deeper layers(over 8 m)being more sensitive than shallower layers(within 8 m).Additionally,the Reynolds num-ber increases with grab operation speed and decreases with increase of slurry density.Based on the results,control parameters for trench excavation in gravel-sand stratum under high groundwater levels were proposed:slurry level to groundwater level difference is≥1.5 m,slurry density is≥11.8 kN/m,surface load is≤356.5 kN,and grab operation speed is≤0.85 m/s.On-site construction validation has shown good results,providing valuable insights for similar projects.

关 键 词：地下连续墙 成槽施工技术 高水位砾砂地层 流体动力学 

分 类 号：U231.3[交通运输工程—道路与铁道工程]