On August 8, 2024, the rectangular pipe jacking project of Sub-item 2 of the Wanqingsha South Supporting Power Cable Tunnel (Phase I) in Nansha District, Guangzhou, constructed by Guangzhou ** Municipal Engineering Co., Ltd. and jacked by Guangzhou Jintu Geotechnical Engineering Technology Co., Ltd., was successfully launched.

This pipe jacking project is located in the Wanqingsha area of Nansha District, Guangzhou. This section is divided into 10 pipe jacking segments, with the longest jacking length of approximately 389.7 m and the shortest jacking length of approximately 72.1 m, and a total jacking length of 3,201.3 m. The pipe jacking works pass beneath Lixinsha East Road and Wanhuan West Road, where road traffic is busy and passenger flow is heavy; the pipe jacking passes beneath rivers three times, successively beneath the Twelfth River, Thirteenth River, and Fourteenth River, with a minimum cover thickness between the river channels and the pipe jacking of approximately 7 m; the pipe jacking section also passes beneath numerous underground municipal pipelines, mainly power, telecommunications, water supply and drainage, and gas pipelines. The surrounding environment of the pipe jacking section is relatively complex, with prefabricated factory buildings, residential houses, high-voltage transmission towers, bridges, and other buildings (structures) distributed nearby.

Satellite Plan View of Pipe Jacking Construction

The cross-sectional dimensions of the pipe jacking works are 3.3 m × 4.4 m, with the longest jacking length of approximately 389.7 m, a cover depth of 6.002 m to 12.437 m, and a minimum horizontal curvature radius of 2,200 m. The works mainly pass through stratum ②-1, the muddy silty clay layer.

Pipe Segment Cross-Section Diagram

Project Characteristics

1. The pipe jacking mainly passes through the muddy silty clay layer, where the soil is relatively soft with low foundation bearing capacity, groundwater is abundant, and the pipe jacking burial depth is large. When breaking through the portal, water and sand inflow is likely, and the machine head is prone to pitching during launch, so the construction risks of pipe jacking launch and reception are high.

2. Of the 10 pipe jacking segments, 7 have jacking lengths greater than 300 m, with the longest jacking length of approximately 389.7 m. These are ultra-long-distance pipe jackings, and the friction resistance of pipe segments during jacking construction is large.

3. In the 389.7 m ultra-long-distance pipe jacking construction, the laser points for measurement are prone to scattering, and four segments involve curved jacking with a minimum curvature radius of 2,200 m, making axis measurement and control highly difficult.

4. The pipe jacking is driven throughout in water-rich, soft muddy soil strata. The soil is relatively soft with poor stability, and the soil mass ahead of the excavation face is prone to flowing mud and collapse risks.

5. The pipe jacking passes laterally at close range beneath existing buildings, bridge piles, etc., and beneath major urban arterial roads. The structural deformation control of existing buildings and structures places high demands on construction.

6. The pipe jacking passage passes beneath numerous pipelines, and pipeline deformation control places high demands on pipe jacking construction.

7. The pipe jacking section passes beneath rivers three times, with a minimum cover thickness at the riverbed of approximately 7 m. Construction is likely to cause soil instability and deformation, resulting in high construction risks.

8. Under water-rich soft stratum conditions, controlling uneven settlement of pipe segments in ultra-long-distance pipe jacking is highly difficult.‍

In response to the project characteristics, key difficulties, and risk points, Guangzhou Jintu will strictly follow the design drawings and specification requirements, meticulously organize construction, apply scientific management, strictly control every technical aspect of construction, carry forward the craftsman spirit, overcome difficulties, and complete this power cable tunnel pipe jacking construction task with high quality and high efficiency.

Integrity, pragmatism, innovation, and development collectively embody the business philosophy and corporate spirit of Guangzhou Jintu. Integrity is the cornerstone, pragmatism is the spirit, innovation is the driving force, and development is the absolute principle. Jintu people work together in unity and collaboration, leveraging their wisdom and talent to overcome one obstacle after another, helping the company become a benchmark and leading enterprise in China's urban underground space and underground engineering construction industry!