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Study on Backfill Grouting Behind the Segment of Double Shield TBM Metro
Tunnel Crossing Water-bearing Fault Zone
(1. Qingdao Metro Line 6 Co., Ltd., Qingdao 266427; 2. Qingdao Metro Group Co., Ltd., Qingdao 266045;
3. School of Mechanics and Civil Engineering, China University of Mining and Technology-Beijing, Beijing 100083;4. China Railway No.2 Engineering Group Co., Ltd., Chengdu 610031)
Abstract For tunnelling through a stratum in water-bearing fault zone by double shield TBM in urban metro construction, the problems such as water inflow and poor self-stability of surrounding rock are very likely to occur.Grouting in the gap between the segment wall and surrounding rock will prevent water inflow, and also reinforce and support the surrounding rock in a timely manner. On this basis, the TBM shield tail blocking plate structure is designed, and a new construction process is devised that allows pea gravel backfilling and synchronous grouting. First,the optimum mix ratio of synchronous grouting slurry is determined through laboratory test. Then based on the positions of the preformed holes of segment and the volume of gap between surrounding rock and segment, the construction process of "three-step pea gravel backfilling" and "three-step grouting" is devised. At last, the process is put to field application. The results indicate: the optimum solution A mix ratio of synchronous grouting slurry is fly ash∶cement∶
water=2.5∶1∶2, the concretion rate is up to 95%, and the double-solution grout with solution A∶solution B=1∶1 has the shortest initial setting time and strongest resistance against water dilution. When this process is applied in practical work, pea gravel backfilling creates solid mass, the backfilled structure is intact, the formed tunnel structure is stable, segment settlement is effectively controlled, and there is no water leakage.
Abstract：
For tunnelling through a stratum in water-bearing fault zone by double shield TBM in urban metro construction, the problems such as water inflow and poor self-stability of surrounding rock are very likely to occur.Grouting in the gap between the segment wall and surrounding rock will prevent water inflow, and also reinforce and support the surrounding rock in a timely manner. On this basis, the TBM shield tail blocking plate structure is designed, and a new construction process is devised that allows pea gravel backfilling and synchronous grouting. First,the optimum mix ratio of synchronous grouting slurry is determined through laboratory test. Then based on the positions of the preformed holes of segment and the volume of gap between surrounding rock and segment, the construction process of "three-step pea gravel backfilling" and "three-step grouting" is devised. At last, the process is put to field application. The results indicate: the optimum solution A mix ratio of synchronous grouting slurry is fly ash∶cement∶
water=2.5∶1∶2, the concretion rate is up to 95%, and the double-solution grout with solution A∶solution B=1∶1 has the shortest initial setting time and strongest resistance against water dilution. When this process is applied in practical work, pea gravel backfilling creates solid mass, the backfilled structure is intact, the formed tunnel structure is stable, segment settlement is effectively controlled, and there is no water leakage.
LIU Quanwei1,
2 YANG Xing3 YE Shoujie1,
2 JIANG Yusheng3 ZHAO Jizeng1 etc
.Study on Backfill Grouting Behind the Segment of Double Shield TBM Metro
Tunnel Crossing Water-bearing Fault Zone[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(6): 255-261
2023, Vol. 60 