In early October 2017, XCMG XTR7/360, the largest tunnel boring machine, went off the production line successfully. The tunnel boring technology of XCMG has led the world and reached a new height of “Made in China”.
The first XTR7/360 tunnel boring machine has been delivered to the reconstruction project of sewage pipe network in a Miao autonomous county of Shaoyang City, Hunan Province. How does it perform?
The project is a city-gate water conservancy tunnel with a full length of 1.2km, an excavation section width of 4.6m, and a height of 6.6m. Above the tunnel are residential buildings and pavement, buried for a depth of about 4m. These buildings have strict requirements on the disturbance on surrounding rock and noise control. The tunnel strata is all rock roadway. The rocks are limestone and granite with saturated uniaxial compressive strength of 90-110MPa, or over 110MPa partially. The project started in 2015, with the tunnel entrance and the tunnel exit commenced at the same time. The entrance was constructed with quartering hammer, and withdrawal was made due to the hard rocks. The exit was exploded with static dynamite blast, with a drill footage of 2-6m per month. After a few months, the construction team withdrew helplessly due to low construction efficiency.
Failed Static Dynamite Blast
All Rock Roadway Tunnel Strata
XCMG XTR7/360 cantilevered tunneler has a weight of 145t, a cutting power of 360/280kw, cutting height and width of more than 7m. The machine focuses on the design of hard rock cutting reliability and has high reliability and strong rock breaking ability. The working mechanism has diverse configuration to adapt to different stratum. It is also equipped with advanced features such as smart roll cable, sound and light alarms, soft start, and remote control.
XTR7/360 tunnel boring machine works in the full cross-section of the project. It has withstood hard rock formation and landslide since construction and shown stable performance. The tunneling efficiency has been significantly improved since its entry.
Local residents expressed their spontaneous thanks to the technical service staff of XCMG:
It rains for months during the rainy season. Last year, rainwater flooded the second floor of the building. When the tunnel is built, the water will be drained and we won’t have to worry. What a job you have done!”