Recently, a 5.48m diameter CREC R277 hard rock TBM developed by China Railway Engineering Equipment Group Co., Ltd. (CREG) has completed the first section of Hubei Maping Phosphate Mine #2 Air Return Inclined Shaft Project in China, which is the first successful application of TBM in the inclined shaft construction of non-coal mines, and is of great significance to the safe and efficient downhill tunnelling of long-distance and large-slope mine inclined shafts.
The section 1 of the project is 2,311.7 m long with the maximum longitudinal slope of -15% and the minimum curve radius of 480m. During construction, the TBM has to overcome many challenges such as crown collapse in unfavorable geological sections, water ingress, and leakage water backflow to the front of the TBM from gantry area.
CREC R277 is therefore equipped with an advanced geological prediction system to achieve the precise identification of geology in front of tunnel face, and innovatively applies the synchronous excavation chamber dewatering technology during the large-slope downhill tunnelling. The TBM has set the records with the maximum daily advances of 29.2 m in the straight section and 25 m in the curved section so far.