Engineering practices of preventing seepage damage of excavations in coastal thick sand layer region
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摘要: 介绍了某邻海基坑工程中三重管旋喷桩与单轴水泥搅拌桩组合式止水帷幕的成功应用。实践证明，这种组合式止水帷幕不但解决了一般单轴搅拌桩在厚砂层地质中垂直度难以保证、咬合不好易形成桩底开叉的难题，又解决了沿海地区涨退潮对旋喷桩施工时水泥浆可能被水流带走难以连续成桩的影响。同时，本工程局部南面区域相对隔水层较薄，设计计算时该区域会形成基坑突涌，因此根据大面积基坑的水文地质情况及基坑渗流计算数据，布置了相应数量的减压井和疏干井，成功避免了基坑的突涌渗流破坏。Abstract: The successful application of sealing curtain in an excavation in thick sand layer coastal region is introduced. The curtain combines triple-tube jet grouting piles with uniaxial cement mixing piles. The practices have proved that the combined curtain has solved the problem of poor interlocking and easy separation at the bottom due to the difficulty of vertical uniaxial cement mixing piles in thick sand layer. It has also solved the difficulty to form continuous jet grouting piles because the cement slurry is easily carried away by tides in coastal region. At the same time, the water-resisting layer is locally thinner in the southern area of the project, which will lead to piping in the design and calculation. Based on the hydrogeological conditions and the calculation, some relief wells and drainage wells are arranged so as to avoid the piping of seepage damage in the project.
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Keywords:
- deep excavation /
- seepage damage /
- sealing curtain /
- sealing well test /
- relief well /
- drainage well
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[1] 广州地区建筑基坑支护技术规定[S]. 1998. (Technical regulations for retaining and protection of building foundation excavations in Guangzhou region[S]. 1998. (in Chinese)) [2] 姚天强, 石振华. 基坑降水手册[M]. 北京: 中国建筑工业出版社. (YAO Tian-qiang, SHI Zhen-hua. The precipitation manual for building foundation excavations[M]. Beijing: China Architecture and Building Press. (in Chinese))
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