Today's Topic

Erqi Road River-Crossing Tunnel (Jiefang Avenue—Yanjiang Avenue Section) Project Successfully Completed‍

Recently, the Erqi Road River-Crossing Tunnel (Jiefang Avenue—Yanjiang Avenue Section) project, invested and constructed by Wuhan Urban Construction Investment Group, successfully completed the concrete pouring of the station section base slab. The open-cut section has fully entered the deep foundation pit base slab construction stage, once again verifying that the foundation pit support form of double-bottom CSM method (cutter soil mixing wall) + underground diaphragm wall is a more efficient and reliable foundation pit support solution for ultra-deep foundation pit construction in high confined water areas.

Project Feature One

Shield Working Shaft Foundation Pit Excavation 47.7 Meters, Water Head Difference Inside and Outside the Pit Reaches 40 Meters‍

The Erqi Road River-Crossing Tunnel is located between the Wuhan Yangtze River Second Bridge and the Erqi Yangtze River Bridge. It is the first double-deck, dual-direction, 6-lane shield tunnel over the Yangtze River, with a shield outer diameter of 15.5 meters, making it the largest-diameter shield tunnel under construction in China. The shield end shaft area is only 70m from the Yangtze River levee, and the ultra-large-diameter shield needs to cross the Yangtze River. The designed excavation depth of the end shaft area reaches 47.7m, with the deepest point equivalent to excavating 16 stories downward.

The ultra-deep excavation depth creates a water head difference of nearly 40m inside and outside the foundation pit. Facing such complex working conditions, any carelessness during construction would cause incalculable losses.‍

Project Zoning Depth Map

Project Feature Two

CSM + Diaphragm Wall Double Insurance, Foundation Pit Seepage Prevention Fully Guaranteed‍

The overall reinforcement of the shield end shaft area adopts CSM equal-thickness cement-soil deep mixing reinforcement, while the overall foundation pit support adopts double-bottom CSM + underground diaphragm wall. On the Wuhan Yangtze River Grade I terrace, the foundation pit is close to the Yangtze River levee, surrounding structures are extremely sensitive, and the working conditions involve ultra-high confined water. All "low-probability, high-risk" problems should be resolutely avoided.

According to the actual pile (wall) quality requirements, after repeated demonstration, it was finally determined to adjust the original design of MJS diaphragm wall joint water stop to continuous closed CSM bottom-sealing water stop, maximizing the safety of the foundation pit!‍

Project Feature Three

CSM Method Equipment Has Low Noise and Slight Disturbance to Ensure Surrounding Safety‍

Because the project is close to the Binfengyuan residential community, which mostly has rammed expanded pile foundations with pile lengths of about 18m, the CSM method is also adopted to minimize the impact of construction on the surrounding environment. The CSM method is in-situ forced mixing under low air pressure and low slurry pressure, with an electro-hydraulic power system. During construction, the "drill one, skip three" construction method can be adopted to further reduce the impact on the surrounding environment. It is truly low-noise, slight-disturbance foundation construction equipment.

Project Feature Four

Core Sampling Rate Above 95%, Core Sampling Pass Rate 100%‍

To ensure the safety of the foundation pit, strict testing was carried out for each process. For CSM, hundreds of wall panels were randomly inspected, with core sampling rates all above 95%, core sample strength of 1.0-3.0Mpa, and a core sampling pass rate of 100%. In the foundation pit connectivity test, the total water outflow of the foundation pit was 36m³/h. The high-quality seepage-proof curtain escorted the foundation pit construction.

Shanghai Jintai has 12 years of application history since its first CSM method equipment was launched in 2011. Over these 12 years, the products have been continuously innovated and improved, and their functions continuously perfected and upgraded. Jintai CSM method equipment occupies an absolutely leading position in China in terms of both product spectrum and application achievements.

Zhengyu Kechuang (Wuhan) Geotechnical Engineering Co., Ltd., as one of the few domestic professional companies focusing on ultra-deep cement-soil mixing wall construction and method promotion, has joined forces with Shanghai Jintai Engineering Machinery Co., Ltd. to contribute to Wuhan's new development and construction.

They continue to deepen and expand their research and promotion of the CSM method, scoring new achievements and scaling new heights in the Erqi Road River-Crossing Tunnel (Jiefang Avenue—Yanjiang Avenue Section) project!‍