富水地层盾构隧道同步注浆惰性充填材料配比与试验研究

为解决富水地层盾构同步注浆普通单液浆存在的易冲散、留存率低、凝结时间长、输送离析堵管等问题，依托长春地铁2号线西延线盾构隧道工程，开展富水地层盾构隧道同步注浆惰性充填材料配比与试验研究。为兼顾同步注浆管片壁后的高充填与浆液在管道中的高流动要求，选择低水泥、高骨料的惰性浆液，并研发一种同步注浆专用充填剂，能够有效减小浆液泌水和离析并加快凝结速度，提高壁后充填强度。试验结果表明，浆液泌水率随充填剂掺量TIR的提高呈现先减小后增大的变化规律，1h后泌水率曲线全部位于泌水合理区IV区的浆液满足工程要求。TIR=1.2%为最优掺入比，TIR过大会增加泌水，同时浆液流动性、凝结速度及早期强度也会得到一定的减弱。通过BC1201E型三维数字视频显微系统对不同龄期的试块进行细观分析，结果表明充填剂可提高浆液的均匀性，减小表面细小孔隙，更有利于管片壁后充填。另外新配比浆液保证现场工程盾构顺利通过风险源地段，最大地表沉降最终控制在12mm以内。

Experimental study on mix proportion of inert filling materials for synchronous grouting of shield tunnel in water-rich strata

To solve the problems of easy dispersion, low retention rate, long setting time, transportation segregation and pipe blockage of ordinary single slurry for synchronous grouting of shield tunnel in water-rich strata, an experimental study was conducted on the mix proportion of inert filling materials based on the shield tunnel project of West extension line of Changchun Metro Line 2. To meet the requirements of high filling behind the segments and high fluidity in the pipeline, the inert slurry with low cement and high aggregate was selected. A special filling agent for synchronous grouting was developed, which could effectively reduce the bleeding and segregation of slurry, accelerate the setting process, and improve the filling strength. The test results show that the bleeding rate of slurry decreases first and then increases with the increase of the filling agent content TIR. After 1 h, the slurry with bleeding rate curve located in the reasonable bleeding area of IV meets the engineering requirements and TIR=1.2% shall be the best mixing ratio. Excessive TIR may increase the bleeding rate and impair the fluidity, setting process, and early strength of the slurry. The BC1201E 3D digital video microscope system was used to analyze the microstructure of slurry specimens at different ages. The results show that the special filling agent can improve the uniformity of the slurry, reduce the small pores on the surface, and improve the filling quality behind the segments. Besides, the new inert filling slurry may ensure the successful passing of shield machine through the section with risk sources, and the maximum ground settlement may be finally controlled within 12mm.