盾构隧道同步注浆增粘型浆液流动特性分析

Analysis of the Flow Characteristics of Synchronous Grouting Viscous Slurry in Shield Tunneling

目前常用絮凝剂改善水泥基同步注浆浆液的水下注浆性能,但絮凝剂在改善浆液抗水分散性的同时,极大降低了浆液的流动性,不利于浆液在管道中泵送。目前,同步注浆浆液的流动性指标参考普通水泥浆液,缺乏浆液流动性关键性能影响指标的测试,无法全面体现增粘型水泥砂浆在同步注浆施工时的流动特性。为此,基于普通水泥砂浆管道流动特性,结合增粘型水泥砂浆改性机理,提出同步注浆增粘型浆液流动性影响指标。同时利用研发的同步注浆浆液流动性模拟试验装置,对增粘型浆液的流动特性以及影响指标进行测试及分析。结果表明:浆液塑性粘度、粘附力和浆液流动压力损失随絮凝剂掺量增加,呈现相似的变化规律,印证了浆液塑性粘度和粘附力是控制浆液流动性的主要指标;浆液的流动性与浆液的塑性粘度及粘附性关系为低粘度调节、高粘附力控制;考虑到施工中对同步注浆浆液抗水分散性、流动性的要求,浆液的粘附力应保证在200 Pa左右,同时根据现场施工需要调控浆液塑性粘度。

Currently,commonly used flocculants are used to improve the underwater grouting performance of cement-based synchronous grouting slurry.However,while flocculants improve the slurry′s resistance to water dispersion,they greatly reduce the flowability of the slurry,which is not conducive to pumping the slurry through pipelines.At present,the flowability index of synchronous grouting slurry refers to ordinary cement slurry,lacking key performance indicators for evaluating the flow characteristics of viscous cement mortar in synchronous grouting construction.Therefore,based on the pipeline flow characteristics of ordinary cement mortar and the modification mechanism of viscous cement mortar,the flowability influencing indicators of synchronous grouting viscous slurry are proposed.At the same time,a developed simulation test device for the flowability of synchronous grouting slurry is used to test and analyze the flow characteristics and influencing indicators of viscous slurry.The research results show that:the plastic viscosity,adhesion force,and pressure loss of the slurry show similar changes with an increase in the dosage of flocculants,confirming that plastic viscosity and adhesion force are the main indicators controlling the flowability of the slurry;the relationship between the flowability of the slurry and its plastic viscosity and adhesion is controlled by low viscosity adjustment and high adhesion force;considering the requirements for the slurry′s resistance to water dispersion and flowability during construction,the adhesion force of the slurry should be maintained at around 200 Pa,and the plastic viscosity of the slurry should be adjusted according to the needs of on-site construction.