跨海隧道泥水盾构泥浆劣化试验研究

为解决泥水盾构在海底掘进时海水及含盐地层侵入导致泥浆性质劣化的问题,以厦门地铁3号线五缘湾站—刘五店站（五刘区间）海底隧道工程为依托,通过膨胀指数试验分析淡水、海水及NaCl溶液膨化造浆的区别,并通过海水混入淡水泥浆试验分析海水对泥浆性质的影响。试验结果表明： 1）相较于淡水造浆,利用海水或NaCl溶液造浆会使膨润土泥浆的电位显著降低,膨润土的膨胀性变差,甚至几乎不能膨化; 2）向膨水质量比为1∶10的淡水泥浆中添加海水,当海水添加质量达到泥浆质量的10%时,泥浆便分层离析、泌水; 3）添加羧甲基纤维素钠（CMC）和HS－3均能提高泥浆稳定性,增加泥浆黏度,降低海水混入时泥浆泌水率。基于以上研究成果,厦门地铁3号线五刘区间采用CMC和HS－3复合改性泥浆实现安全顺利穿越富水高渗透地层。

Experimental Study on Slurry Degradation of Slurry Shield Used in Subsea Tunnel

The slurry degradation induced by seawater and salt bearing formation often occurs to slurry shield boring undersea. As a result, the difference among the slurry formulated by freshwater, seawater and NaCl solution is analyzed by the swelling deformation test based on the subsea tunnel project from Wuyuanwan Station to Liuwudian Station on Xiamen Metro Line 3, and the rule of the property variation of bentonite slurry under seawater intrusion is analyzed by seawater infiltrating freshwater slurry test. The experimental results show that: (1) Slurry formulated by seawater or NaCl solution will significantly reduce the Zeta potential of the bentonite slurry, resulting in poor swelling of the bentonite and even expansibility damage. (2) Under seawater intrusion, the slurry, of which the quality of sodium bentonite is one tenth of that of freshwater, particles and the water separates when the amount of seawater intrusion increases to 10% of the slurry quality. (3) The injection of additives such as CMC and HS 3 into the slurry is beneficial to the stability improvement, resulting in slurry viscosity increase and bleeding rate reduction of slurry with seawater intrusion. By using the composite slurry modified by CMC and HS 3, the Wuyuanwan Station to Liuwudian Station Section on Xiamen Metro Line 3 has been successfully passed through the water rich and high permeable stratum.