Novel PDC cutter for reinforced concrete based on linear and rotational cutting tests

Abstract

In tunnel mechanical excavation, when constructing in densely populated areas, it is challenging to cut through some obstacles, such as piles, tunnel segments, and diaphragm walls, using traditional tools. To address this, herein, a new type of polycrystalline diamond compact (PDC) cutter, which is based on cutters widely used in oil drilling, is used to cut reinforced concrete (RC). A linear cutting platform improved from a shaping machine is used, and the orthogonal test method is employed to investigate the sensitivities of different construction parameters on cutting performance when using a single PDC cutter. Rotational cutting tests with a pipe jacking machine are performed with multiple PDC cutters and their modified forms for RC cutting. The most significant factor is concrete strength, and it is not a changeable factor in practical engineering applications. Thus, the cutting depth should be finely controlled and the cutter taper should be optimized. Furthermore, a new form of PDC cutter with triple teeth is proposed for cutting RC in a pipe jacking machine with circular cutting trajectory. The results show that the conical cutterhead is more suitable for cutting segments than the plane cutterhead owing to its smoother torque and small-scale concrete chips that are formed during the final cutting stages. To avoid damage and wear to the cutter holder, a staggered arrangement of two PDC tools is designed for RC cutting. The optimal advancing speed is determined to be < 1 mm/min because it is most suitable for removing formed steel chips (length < 5 cm) and causes less damage on PDC tools. To adapt to the central turn of an “8″-like trajectory in a planetary oval pipe jacking machine, a cutter holder rotated 30° left and right is used. These results can provide important technical insights for efficient and safe RC cutting using PDC tools with more flexible structures in practical engineering applications.