On March 24, the second rock pipe jacking machine in the CYB8#-CYB9# section of the follow-up optimization project for the interconnection of the Hanjiang, Rongjiang and Lianjiang river systems accurately broke through, marking the successful completion of China's first hard-rock geological double-kilometer-level pipe jacking project after 472 days.

This 1,197-meter hard-rock pipe jacking operation with an inner diameter of 2.8 meters not only set a new domestic record for hard-rock jacking construction, but also achieved a historic leap in China's ultra-long-distance pipe jacking technology from following to leading.

Because this project section crosses granite strata and a complex hydrological environment, it is hailed by the industry as "embroidery on granite." Since the start of construction, the project team of Sinohydro Bureau 14 Co., Ltd. has relied on rich experience and a forward-looking approach to plan ahead, organize meticulously and continuously optimize the design scheme, successively overcoming three major technical fortresses: high water pressure impact when crossing the reservoir area, ultra-hard rock strata with uniaxial compressive strength exceeding 200 MPa, and groundwater-rich fault fracture zones, thereby ensuring steady progress of construction.

Technological innovation became the key to breaking through. The project team pioneered the construction technology of opening a chamber under a reservoir for strata reinforcement in hard-rock pipe jacking and the "tunnel portal water leakage sealing construction technology"; in response to the hard-rock jacking challenge, the team carried out technical improvements to the cutterhead system in the early stage so that the pipe jacking equipment could adapt to working conditions under hard rock; to address problems such as slag return at the machine head, sediment at the pipe bottom and mud loss when crossing fault fracture zones, they optimized the slurry circulation slag discharge method and adopted technical measures to reduce slag return at the machine head and sediment at the pipe bottom; by installing shield tail brushes, flushing slag at the pipe bottom, and using high-viscosity thixotropic slurry and dense mud, they reduced pipeline resistance and solved the difficult problem of smooth jacking construction for long-distance hard-rock pipe jacking.

The follow-up optimization project for the interconnection of the Hanjiang, Rongjiang and Lianjiang river systems is an important component of Guangdong Province's "five vertical and five horizontal" backbone water resource allocation network, and is of great significance for solving resource-based and engineering-based water shortages in eastern Guangdong and accelerating the "Hundred Counties, Thousand Towns and Ten Thousand Villages Project." The project is expected to be ready for water supply by March 2026. After completion, it will be able to allocate water from the Hanjiang River to Chaoyang District and Chaonan District of Shantou City, Puning City of Jieyang City, and Chao'an District of Chaozhou City and other areas, with an average annual water intake of 311 million cubic meters and serving a population of 8.5 million. It will effectively optimize the regional water resource allocation pattern and enhance regional water security capacity, while also helping improve the water environment of the Rongjiang and Lianjiang rivers.

successful breakthrough

breakthrough ceremony site