砂砾地层中盾构隧道衬砌后背回填注浆施工技术

Backfill grouting construction technique for shield tunnel lining in sand and gravel stratum

为提升隧道中注浆的强度与耐久性,需要调整注浆的配比与工艺。因此,本文针对砂砾地层中盾构隧道衬砌后背回填注浆施工技术展开研究。初步确定注浆的两种主要材料为水泥与水玻璃,按照水灰比差异制备三种试件。在此基础上,分别尝试前进式分段注浆与后退式分段注浆两种注浆工艺,并调整外加剂的浓度与水玻璃用量,确定最终的注浆配比。试验结果显示,后退式分段注浆工艺能够更充分地回填衬砌后背中存在的缝隙和空洞;在注浆水灰比为1.0∶1.0时,选用氧化铝作为外加剂能够减缓注浆的凝胶时间,进而为注浆工作调整争取更多时间;在水泥—水玻璃比例为1.0∶0.7时,砂砾层在掘进过程中受到的扰动最小,不易出现塌陷且具有较为良好的耐久性能。

In order to improve the strength and durability of grouting in tunnel,it is necessary to adjust the grouting ratio and technique.The construction technique of backfilling grouting at the back of shield tunnel lining in sand and gravel stratum is studied in this paper.The two main materials of grouting are cement and sodium silicate,and three kinds of specimens are prepared according to the difference of water-cement ratio.On this basis,two kinds of grouting technique,forward and receding segmental grouting were tried.The concentration of admixture and the amount of sodium silicate were adjusted,and the final grouting ratio was determined.The test results show that the receding segmental grouting process can more fully backfill the gaps and voids in the back of the lining;when the water-cement ratio of grouting is 1.0∶1.0,the use of alumina as admixture can slow down the gelling time of grouting,so as to get more time for the adjustment of grouting work;when the ratio of cement to sodium silicate is 1.0∶0.7,the disturbance to sand and gravel stratum is the small in the process of tunneling,and the tunnel is not easy to collapse and has relatively good durability.