China Railway 25th Bureau Qingdao Metro Line 2 Shield Construction Project
Project Background
The Qingdao Metro Line 2 project, undertaken by China Railway 25th Bureau, is a key urban underground transit infrastructure crossing multiple complex soil layers including cohesive clay and water-rich sand stratum. The tunnel construction required high-performance shield auxiliary chemicals that could sustain long-lasting sealing effect under high groundwater pressure, reduce excavation resistance of sticky soil, and minimize equipment wear during continuous tunneling operation.
Project Details
|
Parameter |
Detail |
|
Client |
China Railway 25th Bureau Group Co., Ltd. |
|
Project |
Qingdao Metro Line 2 Shield Tunnel Construction Project |
|
Location |
Qingdao, Shandong Province, China |
|
Application |
Subway shield tunneling, tail sealing & soil conditioning |
|
Products Supplied |
Shield tail sealing grease, shield tunneling foam agent |
|
Project Scale |
Multi-kilometer urban tunnel construction section |
Challenges
01 High groundwater pressure
The tunnel section features abundant underground water, which brought risks of slurry leakage, water inflow at shield tail without reliable sealing materials.
02 Cohesive sticky clay stratum
Local clay soil easily adhered to cutterhead and formed mud cake, leading to high tunneling torque, slow advance speed and extra power consumption.
03 Long continuous construction cycle
The project adopted non-stop shift tunneling, requiring stable, long-efficiency chemicals without frequent refilling and performance attenuation.
04 Strict on-site construction coordination
Material delivery and technical parameters needed to fully match daily tunneling progress to avoid construction suspension.
Solution
HDC’s technical team analyzed local stratum data and tunneling equipment parameters, then customized a matched set of shield auxiliary chemical solution:
-
01
Shield tail sealing grease
Form dense waterproof grease layers between multi-layer tail brushes, resist high-pressure underground water and cement slurry backflow, reduce abrasion of tail brush accessories and extend service cycle.
-
02
Shield tunneling foam agent
Inject into excavation chamber to soften sticky clay, disperse soil aggregates, eliminate mud cake adhesion on cutterhead, lower tunneling torque and improve excavation efficiency.
-
03
On-site professional technical support
HDC field engineers cooperated with shield operators to adjust foam injection ratio and grease filling frequency according to real-time stratum changes.
Results
· All tunnel sections finished construction fully complying with design standards, passed acceptance inspection of China Railway 25th Bureau without leakage or rework.
· Mud cake issue of clay stratum was effectively eliminated, tunneling advance speed increased significantly thanks to foam conditioning.
· Zero water and slurry leakage at shield tail during whole construction period; tail brush wear rate reduced obviously.
· Stable batch delivery schedule kept consistent with tunneling plan, no material shortage or construction delay occurred.
· Highly positive client recognition: China Railway 25th Bureau praised HDC’s stable product performance and timely on-site technical service.
