咸水环境下泥水盾构泥浆配比试验研究

Experimental study on slurry mixing proportion in salt water by slurry shield

在水下盾构掘进过程中出现带压开舱检修情况时,如何在高渗透性地层形成质量较好的泥膜从而保证开挖面稳定,是保障工程安全与进度的重要前提。以青岛地铁跨海段隧道掘进工程为依托,自主设计试验装置开展咸水泥浆配比及渗透成膜试验,并设置淡水泥浆作为对照组。采用控制变量法和析因分析法研究膨润土、羧甲基纤维素(CMC)、碳酸钠等不同制浆材料引起的泥浆相对密度和黏度变化对泥浆滤水量的影响。试验结果表明:在咸水泥浆中,随着膨润土含量的增加,泥浆相对密度变大,可以显著降低泥膜的滤水量,增加CMC含量可以提高泥浆黏度从而更易成膜,对本工程咸水环境高渗透性砂土地层而言,采用相对密度为1.18~1.23 g/cm^(3)、黏度25~30 s的配制方案,可取得良好的成膜效果。

During the construction of underwater tunnels,the drilling of the shields has often need to be stopped to check and repair the cutting tools under hyperbaric conditions.Moreover,methods of forming a high quality slurry membrane in high permeability stratum for ensuring the stability of the excavation surface greatly restricts the safety and progress of the project.In this paper,based on the cross-sea tunnel excavation project of Qingdao metro,devices for the salt water slurry ratio and permeability membrane forming test was initially designed,independently developed,and fresh water slurry was established as the control group.Afterwards,the effect of the relative density and viscosity of the slurry caused by different pulping materials,such as bentonite,carboxymethyl cellulose(CMC)and sodium carbonate,on the filtration capacity of the slurry was studied by using the control variable method and the factorial analysis method.The test results show that in the salt water slurry,with the increase of bentonite content,the relative density of the mud becomes larger.This can significantly reduce the water filtration of the slurry membrane,and the increase of CMC content can improve the viscosity of the slurry,which makes it easier to form the membrane.In this project,it is found that the preparation scheme with relative density of 1.18~1.23 g/cm^(3) and the viscosity of 25~30 s can achieve strong membrane-forming effect.