Development and Application of Anti Caking Mud Cake Improver for Composite Sand Layer Shield Tunneling Cutterhead
During the process of shield tunneling through unfavorable geological conditions,it is easy to encounter phenomena such as mud cake formation and severe damage to the cutterhead,which can cause safety accidents in severe cases.Based on this,relying on the engineering of crossing fine sand and medium coarse sand layers in the section between Shuishang Park Station and Bailinzhuang Station of Shijiazhuang Metro Line 3,the phenomenon of mud cake formation on the cutterhead during shield tunneling through composite sand layers was analyzed.And different proportions of bentonite slurry and foam mixed improver were designed.Based on slump test and direct shear test,the best proportion suitable for this project was obtained and applied to the site.The research shows that mud cake formation occurs on the cutterhead when the shield passes through silty fine sand and medium coarse sand strata,and the shield tunneling parameters are poor.In the test,reducing the concentration of bentonite,increasing the injection ratio of bentonite,and increasing the injection ratio of foam can improve the slump value,and the improved muck cohesion increases,and the internal friction angle decreases.The optimal ratio of the modifier in this project is that the injection ratio of bentonite and foam is both15%,in which the concentration of bentonite is 10%(Scheme 4).After this improvement,the tunneling speed of the shield machine is significantly improved,the torque is reduced,and the improvement effect is significant,which can provide reference for similar projects.
sand layermud cake formation on cutterheadmuck improverexcavation parameter
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