Abstract:

The Shangteng StationDadao Station on Fuzhou Metro Line No.1 in high water pressure and high permeability sandy stratum is constructed by earth pressure balance (EPB) shield and prone to water gushing accidents. Therefore, the ground conditioning technology by taking sodium bentonite, carboxymethylcellulose (CMC) and polyacrylamide as the main materials is used to carry out laboratory test and site test and study the comprehensive ground conditioning method for EPB shield tunneling in high water pressure and high permeability sandy stratum. The study results show that: 1) The ground conditioning effect is not obvious when using single material. 2) The workability and permeability of the soil can be improved significantly by using mixed solution of sodium bentonite and CMC, while, the slump of the soil can not meet the requirement in available concentration range of solution. 3) The workability and permeability of the supersaturated medium sand can be improved significantly by using mixed solution of sodium bentoniteCMC cooperatively with polyacrylamide solution. 4) The solution of 100∶5 mixing solution of 3% polyacrylamide solution cooperatively mixed with 10∶2.5 mixing solution of bentonite (with mass fraction of 1∶10) and 5‰ CMC is adopted in Fuzhou Metro Line No.1; and the conditioning effect is verified by sample test.

Key words: earth pressure balance (EPB) shield, high water pressure and high permeability sandy stratum, water gushing, ground conditioning, site test