On January 18, the super-large diameter (15.53m) slurry shield machine "Mawan" successfully rolled off the production line. The equipment will be applied to the Shenzhen Mawan Cross-Sea Passage, currently the largest-diameter subsea highway tunnel constructed by shield method in China.

The shield-driven section of the Mawan Cross-Sea Passage is 2,063 meters long, and there are many difficulties in construction: "Long"——50% of the driving route consists of soft-hard uneven rock strata, and 34.15% is full-face hard rock, so the equipment traverses high-strength rock strata over a long distance; "Difficult"——crossing complex subsea terrain easily causes the shield machine to float and deviate from the preset trajectory, with large cutter wear and high cutter replacement risk, making construction quite difficult; "Deep"——the subsea tunnel is located more than 40 meters underwater, with a maximum water pressure of 5 bar and rock strength of up to 193 MPa; "Large"——the tunnel cross-section is large, with a segment outer diameter of 15 meters, adopting currently China's largest subsea shield equipment, which places extremely high demands on equipment performance and construction technology.

The equipment is an air-cushion slurry shield machine with an excavation diameter of 15.53 meters, a total length of about 140 meters, and a weight of 4,650 tons. It features atmospheric cutter replacement, cutterhead swing and telescoping, main drive pressurization, a dual-air-circuit pressure maintenance system, and an efficient muck screening system. It is also equipped with a large-flow slurry circulation system to ensure rapid tunneling of the shield machine in composite strata and to better cope with engineering risks under complex working conditions.

The Mawan Cross-Sea Passage is an amphibious project, divided into two parts: ground roads and underground roads. The tunnel has a total length of 6,280 meters, of which the underground road is planned as an urban expressway with dual carriageways and six lanes, designed at a speed of 80 km/h. After completion, the project will undertake port-dredging freight traffic for the Nanshan Port Area, while also serving passenger transport links between the Mawan and Chiwan areas and the Dachan Bay area, realizing the "separation of passengers and freight" for external traffic in Qianhai. It is of great significance for reducing the impact of minor port-dredging traffic on the Qianhai traffic environment, improving the regional road network structure, and supporting Qianhai's high-end positioning.