Comparative analysis of adaptability of open TBM small curve turning radius

Aiming at the problems of difficult operation and low excavation accuracy of open TBM in the process of small curve cornering, the structural mechanism, and motion characteristics of the traditional Horizontal main beam type TBM and the new 8-SPS V-type TBM mainframe were compared and studied. Based on the drainage channel project of a pumped storage power station, the factors affecting the minimum turning radius of TBM were analyzed by establishing two TBM main engine turning direction models. Secondly, the design of two open TBM mainframes with a diameter of ϕ3530 mm is improved. Finally, the relationship between the displacement and velocity change between the cutterhead and the propulsion cylinder under the straight-line boring condition and the small curve turning boring condition of TBM was analyzed by ADAMS software. The results show that when the tunnel design axis has a large turning radius and is dominated by straight segments, the TBM propulsion system with horizontal main beam type has higher excavation efficiency. The 8-SPS V-type TBM cutterhead attitude change is more flexible, which is more suitable for complex and changeable small curve corner boring. Moreover, the 8-SPS propulsion system is symmetrical, and the speed of each cylinder changes more gently during the turning process, the cylinder attitude of TBM is easy to control during the small curve turning and propulsion, the boring accuracy is higher, and the propulsion system compliance is better.