Enclosure Structure of Guanggang New Town Station on Guangzhou Metro Line 10 Completed

Recently, Phase II enclosure structure of Guanggang New Town Station on Guangzhou Metro Line 10 has been completed, marking the entire completion of the enclosure structures of this station. This is the fourth station of Line 10 that with the enclosure structure built by Beijing Urban Construction Investment & Development Co., Ltd, and the sixth station of the entire line with completed enclosure structure. The station has officially entered the construction stage of the main structure, which has saved precious time for the next stage of building shield tunnel from Guanggang New Town Station to Dongsha Station to start on time.

Guanggang New Town Station is the 13th station in the newly built section of Line 10 project, which is connected with Dongsha Station in the east and Xilang Station in the west. It provided shield tunneling starting wells for the station on the 2nd basement of Shuangdao line 4 and its east and west terminals. The station adopts open-cut construction method, and the main enclosure structure adopts a scheme that uses bored cast-in-place pile, check the water curtain for jet grouting piles and internal support. The construction project of the station will be delivered in two phases, and the first phase of building the enclosing structure has been successfully completed by the end of August 2020. At present, the preparation work for the shield tunneling in the section from Guanggang New Town Station to Xilang Station is under way.

In order to enter the site and begin construction as soon as possible, the 1st working area of Guangzhou Line 10 actively contacted the Land Management Department of the Headquarter and the 3rd/10th Construction Management Department, coordinated and communicated repeatedly with the local units. On March 25 this year, all sites of the phase II were handed over. On March 27, the project team immediately set about retaining piles construction in phase II comprehensively through the scientific method and reasonable arranged working procedure. In just 45 days, It successfully built 365 retaining piles, 73 uplift piles, 637 jet grouting piles, and 580 single axial mixing piles. Among them, the retaining piles and uplift piles adopts a construction technology of long liners and dry drilling, which greatly accelerated the site construction.

It is reported that before the construction of the retaining pile, the construction team in Guangzhou Line 10 Work Field 1 carefully compared the differences between the traditional mud wall protection construction and the technology of long liners and dry drilling. Considering that the site is a combination of soft and hard strata, and the upper soft soil layer is of poor self-stability and rich in groundwater, at the same time there is higher requirement for control on mud index and greater risk of hole collapse, the construction team finally decided to adopt retaining piles that built by long liners and dry drilling, so that there is no need to mix mud, and construction water and resources are saved. There are also other advantages. The construction will not produce mud and other waste, drilling residue can also be backfilled for reuse, which is conducive to the site safety, civilized construction and environmental protection. This technology is less dependent on mechanical resources, and does not need to control the mud index after drilling, so it can speed up the construction progress and save cost. In the field, the water-rich miscellaneous fill layer is thick, and there are silt and sand layers locally. The long liners are used to cross these detrimental geological layers, and adopting dry drilling can reduce the risk of hole collapse.