复合砂层盾构刀盘防结泥饼改良剂研制与应用

Development and Application of Anti Caking Mud Cake Improver for Composite Sand Layer Shield Tunneling Cutterhead

盾构穿越不良地质过程中易出现刀盘结泥饼、严重破损等现象,严重时引起安全事故。基于此,依托石家庄地铁三号线水上公园站~柏林庄站区间穿越粉细砂、中粗砂地层工程,分析了盾构穿越复合砂层过程中刀盘结泥饼现象;并设计不同配比膨润土泥浆和泡沫混合改良剂,基于坍落度试验和直剪试验,获得了适用于本工程的最佳配比,并应用于现场。研究表明:盾构穿越粉细砂、中粗砂地层而发生刀盘结泥饼、盾构掘进参数不佳情况,试验中降低膨润土浓度、增大膨润土注入比、增大泡沫注入比均能提升坍落度值,且经过改良后的渣土粘聚力增大,内摩擦角减小;本工程改良剂最佳配比是膨润土和泡沫注入比均为15%,其中膨润土浓度为10%(方案4),经此改良后,盾构机掘进速度明显提升,扭矩降低,改良效果显著,可为类似工程提供参考。

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 both 15%,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.