泥水平衡盾构中海水泥浆性质试验研究

采用泥水平衡式盾构开挖海底隧道,考虑地层富含海水,泥水仓泥浆可采用海水泥浆和淡水泥浆。利用海水配制泥浆可以大大降低施工成本,但海水富含的离子成分引起海水泥浆性质降低。为明确海水泥浆性质与不同影响因素的定量关系,笔者开展了不同膨润土类型、膨润土含量、不同海水掺入量及静置时间对海水泥浆性质的影响试验,认为:海水离子对海水泥浆的黏度和胶体率的影响巨大,分析不同影响因素对泥浆性质指标的影响规律,提出了膨润土与海水离子的中和作用关系,采取增加膨润土而改善海水泥浆性质的措施并不经济;同时,采用海水泥浆时不可停止泥浆搅拌与循环,防止海水泥浆离析。研究成果明确了海水泥浆性质与不同影响因素的定量关系,对于泥水平衡盾构采用海水泥浆的认知与配制具有重要的指导作用。

Experimental Study on Properties of Seawater Slurry for Mud-balanced Shield Construction

The slurry balance shield is used to excavate the subsea tunnel.Considering that the stratum is rich in seawater,the slurry in the mud tank can be seawater slurry and fresh water slurry.Suing sea water to configure slurry can greatly reduce the construction cost,but ionic composition in sea water cause a decrease in the properties of seawater slurry.To clarify the quantitative relationship between the seawater slurry and different influencing factors,experiments on the effects of different types of bentonite,bentonite proportion,different seawater incorporation proportion and standing time on the properties of seawater slurry were carried out.The research results show that the influence of seawater ions on the viscosity and colloidal rate of seawater slurry is huge.And by analysing the influence law of different influencing factors on the properties of slurry,the neutralization relationship between bentonite and seawater ions was proposed,and the measures to increase the properties of sea cement by increasing bentonite are not economical.When using seawater slurry,the slurry mixing and circulation should not be stopped to prevent the separation of seawater slurry.The research results clarify the quantitative relationship between the properties of seawater slurry and different influencing factors,and have an important guiding role for the understanding and preparation of seawater slurry using mud-balanced shield.