Dynamic fragmentation and chip formation of water-soaked rock in linear cutting with a coupled moisture migration-fracture model

Abstract

Water can greatly influence the mechanical properties and dynamic fracture of underground rock mass. However, the dynamic fragmentation and chip formation of water-soaked rock in linear cutting is neglected. In this work, a coupled moisture migration-fracture model is utilized to investigate this problem. First, the water weakening effect on rock mechanical parameters is introduced in the coupled model according to a fitting laboratory test. Then, the uniaxial tensile, uniaxial compression, triaxial compression, and swelling experiments are utilized to calibrate the input micro-parameters. Subsequently, a series of scratch tests are carried out on the water-soaked rock samples. The stress evolution, fragmentation mode, cutting force, crack number, extent of fracture zone, chip shape, chip area, cutting work, and mechanical specific energy (MSE) with different water content are studied. The results indicate that as water content increases, the rock sample changes from brittle failure to ductile failure in linear cutting, the peak cutting force gradually decreases, and the chip area first becomes larger and then smaller, while the MSE shows an opposite trend. Especially, a water content of 2% can bring the largest chip area and the highest cutting efficiency. Moreover, the effects of cutting velocity and cutting depth on the above indexes are discussed. Finally, a complex specimen composed of half wet and half dry rock is built to further demonstrate the influence of water on rock dynamic fragmentation and chip formation in linear cutting. The modeling results in this paper provide new insights into the influence mechanism of water on rock dynamic fragmentation, chip formation, and cutting efficiency in linear cutting.