Encountering water-rich sand stratum geology with soft upper layers and hard lower layers

Traditional trenching machines have no way to cope?

XCMG's complete set of piling machinery at Qingdao Metro Line 9

"Flow-line" operation

Not only perfectly completed the trenching, but also advanced the construction period by half a month

Recently, the first ultra-hazardous major project of Zhengyang Middle Road Station—the underground diaphragm wall construction—was completed 16 days ahead of schedule in the Phase I Section 1 project of Qingdao Metro Line 9.

Zhengyang Middle Road Station has a total length of 155 meters, a foundation pit depth of about 31.5 meters, and a standard section width of 23.5 meters. It is a four-story underground double-column three-span frame structure and the only four-story station on Line 9. The average depth of the underground diaphragm wall is about 36.5 meters, making it the deepest diaphragm wall since the construction of Qingdao Metro.

Faced with water-rich sand stratum geology featuring soft upper layers and hard lower layers, the construction party needed to overcome difficulties such as high stratum permeability, poor self-stability, strong fluidity, and easy occurrence of collapse and piping during trenching. To this end, the project department innovatively adopted the trenching process of "rotary drilling rig + trenching machine + double-wheel trench cutter."

Through comprehensive investigation and analysis, XCMG technical personnel and project personnel offered advice on equipment selection for the project and dynamically adjusted the construction procedures. Ultimately, XCMG XR420E rotary drilling rig, XG700E underground diaphragm wall hydraulic grab, and XTC120 double-wheel trench cutter were deployed together, cooperating with the construction method of pilot hole drilling by rotary drilling rig + grabbing by grab + rock milling by trench cutter, with three XCMG piling machines carrying out "flow-line" operation.

The XR420E rotary drilling rig took the lead in drilling pilot holes. After the XCMG diaphragm wall hydraulic grab grabbed to a certain depth, the hard rock stratum was milled by the XCMG double-wheel trench cutter, maximizing the efficiency of complete-set construction!

Drilling into hard rock and forming the wall by grabbing and milling. XCMG's complete set of piling machinery completed the diaphragm wall construction in only 75 days, 15 days ahead of the planned construction period, effectively ensuring the smooth progress of subsequent construction tasks.