Recently, the rectangular pipe jacking for the street-crossing passage at Exit A of Panhuo Road Station on Ningbo Metro Line 4, undertaken by Guangzhou Jintu Geotechnical Engineering Technology Co., Ltd., was successfully completed.

The project is located on the east side of the intersection of Canghai Road and Panhuo Road in Yinzhou District, Ningbo City, and is the street-crossing passage at Exit A of Panhuo Road Station on Ningbo Metro Line 4. The passage connects to Exit A of Panhuo Road Station in the north and the Shimao Plaza plot in the south. It is an important passage linking Decathlon and the Shimao Plaza plot, and is constructed using rectangular pipe jacking. The pipe jacking passes from north to south beneath the municipal road Panhuo Road, where ground traffic is busy. There are many major buildings and structures in the surrounding area, including shopping malls, residences, restaurants, hotels, and office buildings. It passes beneath multiple municipal pipelines, including gas, water supply, rainwater, sewage, power supply, and communication conduits and cables. Among them, the vertical clear distance between the DN300 concrete sewage pipe and the pipe jacking is only 1.45 m.

Plan view of the pipe jacking project

The cross-sectional dimensions of the pipe jacking are 7.5 m × 4.3 m, with a length of approximately 38.3 m and a longitudinal jacking gradient of 1%. The upper cover soil thickness is approximately 5.3 m to 5.6 m, and the strata crossed are mainly silty clay layers.

Geological section of the pipe jacking project

Cross-section of the pipe segment

Project Characteristics

1. The pipe jacking passes beneath a busy urban road with heavy ground traffic and high vehicle volume, so strict requirements are imposed on ground deformation control during pipe jacking construction.

2. The pipe jacking passes beneath numerous municipal pipelines, among which the vertical clear distance between the DN300 concrete sewage pipe and the pipe jacking is only 1.45 m. Improper construction may easily cause the sewage pipe to rupture, and in severe cases may lead to jacking failure. Therefore, pipeline protection imposes high precision requirements on pipe jacking construction.

3. The pipe jacking passes through silty clay layers with high compressibility and low foundation bearing capacity. During launching, the pipe jacking machine may experience nose-diving. During the launching stage, measures such as soil reinforcement at the portal, attitude control, and tie-back measures are required to prevent the machine head from sinking.

During construction, Guangzhou Jintu strictly followed the requirements of the owner, design drawings, and specifications, strictly controlled every technical aspect of construction, carried forward the craftsman spirit, overcame difficulties, and ultimately successfully completed the pipe jacking task.

With meticulous workmanship and safe production, Jintu quality is crafted with ingenuity. Build a project, establish a monument. Guangzhou Jintu is willing to work with you to push the cause of trenchless underground engineering to new heights and create greater brilliance.