Abstract:

The ground surface settlement and building damage are easily occurred during earth pressure balance shield crossing underneath concentrated building group in sensitive soft soil stratum. Hence, the horizontal directed grouting reinforcement technology is proposed based on shield crossing underneath Xingzhongwei building group reinforcement project of Guangzhou Metro Line No.14. The technology combines horizontal directed drilling technology with ground surface grouting technology, uses the wireless MWD system to measure, collect, analyze and locate, and grouts through speciallymade steel valve pipe. The drilling technology of horizontal holes is introduced； and the applicable effect and economic benefit of the technology are analyzed. The study results show that: (1) By using the horizontal directed grouting reinforcement technology, the deformation of reinforced zone is controlled within ± 5 mm； no building cracking, tilting and collapsing happen; and the shield crosses underneath concentrated building group in soft soil stratum safely and smoothly. (2)The cost is saved by more than RMB 6 million compared with MJS high pressure jet grouting pile reinforcement scheme, which shows remarkable economic benefit.

Key words: soft soil stratum, shield, underneath crossing, horizontal directed grouting, building group, reinforcement technology