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Construction Methods of Longitudinal Synchronous Grouting for Tunnel
Crown Secondary Lining Voids
(1. China Railway 18th Bureau Group Co. Ltd., Tianjin 300222; 2. College of Transportation Engineering, Nanjing Tech University, Nanjing 211816; 3. The Second Engineering Co., LTD., China Railway 18th Bureau Group, Tangshan 063000;4. Civil Engineering and Architecture ,Southwest University of Science and Technology Civil ,Mianyang 621010)
Abstract Conventional void prevention technologies for the crown of secondary tunnel linings struggle to signifi?
cantly reduce void formation and often result in layering between cast-in-place concrete and grouts. To address these issues, a study was conducted based on the Qu'ao Tunnel on the Lanzhou-Hezuo Railway. Using numerical simulation, the impact of crown voids and asynchronous grouting on the stress behaviors of the lining structure was analyzed. A longitudinal synchronous grouting technology for the crown of secondary linings was proposed, and its effectiveness was verified through field applications and cross- detection using various specifications of ground-penetrating radar. The findings are as follows: (1) Compared to a dense state, crown voids and asynchronous grouting increase the minimum principal stress of the crown by 86% and 39%, respectively. This indicates that crown voids pose the greatest safety risk to secondary linings, and layering between grouts and concrete is also a weak point in the structure. Grouting must be synchronized with concrete casting to ensure the integrity of secondary lining; (2)The proposed longitudinal synchronous grouting technology involves arranging grouting pipes with vent openings along the longitudinal direction within the inner edge of the waterproof board at the crown. Grouting is performed immediately after concrete placement and compaction, eliminating blind spots in radial grouting and avoiding cavities
or density defects. This also eliminates the composite beam effect in the lining structure and enhances its overall load-bearing capacity; (3) The construction method for longitudinal synchronous grouting is simple to operate and significantly reduces costs compared to radial grouting with mold.
Abstract：
Conventional void prevention technologies for the crown of secondary tunnel linings struggle to signifi?
cantly reduce void formation and often result in layering between cast-in-place concrete and grouts. To address these issues, a study was conducted based on the Qu'ao Tunnel on the Lanzhou-Hezuo Railway. Using numerical simulation, the impact of crown voids and asynchronous grouting on the stress behaviors of the lining structure was analyzed. A longitudinal synchronous grouting technology for the crown of secondary linings was proposed, and its effectiveness was verified through field applications and cross- detection using various specifications of ground-penetrating radar. The findings are as follows: (1) Compared to a dense state, crown voids and asynchronous grouting increase the minimum principal stress of the crown by 86% and 39%, respectively. This indicates that crown voids pose the greatest safety risk to secondary linings, and layering between grouts and concrete is also a weak point in the structure. Grouting must be synchronized with concrete casting to ensure the integrity of secondary lining; (2)The proposed longitudinal synchronous grouting technology involves arranging grouting pipes with vent openings along the longitudinal direction within the inner edge of the waterproof board at the crown. Grouting is performed immediately after concrete placement and compaction, eliminating blind spots in radial grouting and avoiding cavities
or density defects. This also eliminates the composite beam effect in the lining structure and enhances its overall load-bearing capacity; (3) The construction method for longitudinal synchronous grouting is simple to operate and significantly reduces costs compared to radial grouting with mold.
WANG Lichuan1,
2 GE Lihui3 WANG Haiyan2 KONG Chao4 LI Qingbin1 WANG Yuntao3 LIU Yufei1
.Construction Methods of Longitudinal Synchronous Grouting for Tunnel
Crown Secondary Lining Voids[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(6): 269-277
2024, Vol. 61 