Mechanical Properties and Influencing Factors of Shield Cutting Existing Station Supporting Piles

Based on the shield-cutting existing station supporting piles project of Zhengzhou metro line 6, the process and mechanism of concrete in the process of pile cutting were analyzed by establishing a three-dimensional model of concrete with a cutter. The magnitude and variation rules of cutting force, penetration force, and tangential force were explored. The variation rules of cutting force with four factors of cutting speed, cutting depth, cutter width, and tool rake angle were explored. The correctness of the numerical model and results were verified by the theoretical analysis method. Finally, the significance of the influencing factors of pile cutting was studied by means of range analysis and variance analysis using the orthogonal test method, and the cutter parameters were optimized. The cutting mechanism is that the front concrete is compressed and crushed to produce a dense core. The cutting force increases rapidly to its maximum value in a short time during the cutting process. The cutting force is always larger than the penetration force and tangential force. The cutter contact force basically remains unchanged with the change in cutting speed; however, it increases with the increase in cutting depth and cutter width. The significant order of the three influencing factors is cutting depth, cutter width, and rake angle. It is suggested that the cutting depth be adjusted preferentially, followed by the cutter width. And the principle of rake angle should be considered last.