承压水层下多孔同步注浆止水技术

Porous Synchronous Grouting,Water-Sealing Techniques for Construction in the Stratum with Pressure-Bearing Water

北京地铁某项目基坑基底位于承压水层中,由于受承压水影响,基坑开挖过程中因隔水层厚度不足导致基底出现涌水涌砂现象,需进行注浆止水,选用多孔同步深孔注浆施工技术。即多孔同步向承压水层中注入水泥水玻璃+速凝剂混合液体,瞬间形成固结体,达到改良土层的目的;通过多孔同步注浆,使注浆混合液体达到互相补充咬合的效果,同时将承压水挤排,形成止水帷幕,能有效的解决承压水层下基坑涌水涌砂现象,并对基底进行了加固处理,在节约工期和提高经济效益方面取得了良好效果。为今后类似地层承压水的治理及基底的加固处理提供了宝贵的技术经验。

Owing to the fact that the bottom of the foundation pit of a certain project of the Beijing Subway is located in the stratum of pressure-bearing underground water,the construction of the foundation pit is affected by the pressure-bearing water and the thickness of the water-stopping layer is insufficient,the phenomena of water gush and sand gush occur at the bottom of the foundation pit,in which case slip-casting has to be performed to stop underground water from gushing,and the porous-synchronization-slip-casting construction technique is applied.To be more specific,a mixed liquid of cement,sodium silicate and fast-hardening agent is slip-cast into the stratum with pressure-bearing water,which will instantly form a solid body and helps improve the geological properties of the stratum.Through the porous synchronous grouting,the inter-complementary and interocclusion effects of the grouted mixture are realized.In the meanwhile,the pressure-bearing water is squeezed out and drained,and a water curtain is formed,all of which help effectively solve the problems of water gush and sand gush in the foundation pit located in the stratum with pressure-bearing underground water.The paper may serve as a valuable reference for the treatment of pressure-bearing underground water and the consolidation of foundation pits.