Recently, the Guangzhou揭榜挂帅 project "Development and Application of Complete Sets of Equipment for Rail Transit Underground Engineering in Complex Environments," led by Guangzhou Metro Group and jointly undertaken by CRCHI (China Railway Construction Heavy Industry) together with Guangzhou Metro Design Institute, China Railway Construction South China Construction, China Railway 15th Bureau, Sun Yat-sen University, and other units, has once again achieved a breakthrough: the development and application of China's first domestic composite caisson-type shaft machine has succeeded, marking the smooth completion of the project's first-phase research tasks and the achievement of important practical results.

Construction site of China's first domestic composite caisson-type shaft machine "Future"

It is reported that China's first domestic composite caisson-type shaft machine, "Future," has completed the dual-shaft excavation task at Shaft No. 2 of the shield section from Jingxi Road to Baiyun Dongping on the Guangzhou-Huadu Intercity Railway (hereinafter referred to as Jingbai No. 2 Shaft), marking the successful verification of the vertical mechanical shaft construction technology applied for the first time in China's rail transit construction field. Shield shaft construction for rail transit in China has entered a new era of mechanized construction. This construction method adopts a non-drainage excavation process inside the shaft, greatly reducing the cost of the retaining structure and minimizing the impact on the surrounding environment, while achieving unmanned operation underground and minimal personnel on the surface, substantially improving the safety of shaft construction.

Jingbai No. 2 Shaft has segment outer diameter of 14 meters, inner diameter of 13 meters, and a depth of 37.2 meters. This shaft boring machine successively traversed backfill soil, silty fine sand, silty clay, sandy cohesive soil, completely weathered granite, strongly weathered granite, moderately weathered granite, and slightly weathered granite strata, which are typical composite strata in South China, and there exist large quantities of boulders and adverse geological conditions such as large undulations of the rock surface, along with abundant groundwater, placing extremely high demands on equipment reliability and making construction extremely difficult.

Aerial view of "Future" construction

In response to the challenges of high water pressure, high hardness, large boulders, and large undulations of the rock surface, the CRCHI research and development team conducted extensive investigation and thorough research, and carried out targeted design of the equipment through theoretical model analysis, technical verification, and other methods. On the basis of completing the right-line shaft construction, they summarized experience and optimized and improved the equipment and construction technology, enhancing the equipment's adaptability and excavation efficiency in hard rock and boulder strata, and completed the left-line shaft construction task in only 34 days.

CRCHI has overcome difficulties and continuously innovated in the field of shaft boring machine development. Another major national heavy equipment—the world's largest-diameter 23-meter shaft boring machine "Dream"—is entering the critical stage of on-site assembly and commissioning and is about to be launched, which will create new glory in the field of urban mechanized shaft construction!