Analytical method and damage evolution mechanism of coal and rock bursting based on Hamiltonian mechanics

In order to study the loading state of the coal body in front of the heading face of the outburst coal seam and the nonlinear mechanical transfer path of the in-situ coal and rock mass under static and dynamic loads, a mathematical model of the transversely isotropic layered combined coal and rock mass was established by using the Hamilton mechanical system, and the symplectic space-time subdomain method was used to solve the interlayer dynamic mechanical transfer path of the coal and rock mass. This study investigates the unloading-reloading process of excavation-induced stress waves and its effects on the coal-rock mass ahead of the tunneling face. The results show central stress concentration with attenuation along the short and long axes, and an "X"-shaped shear failure along the diagonal. Plastic loading waves overtaking elastic unloading waves induce delamination at 0.02, 0.03 and 0.06 s, while radial deformation causes additional delamination at 0.004 and 0.028 s. Analysis based on the Mohr-Coulomb criterion and strain energy density reveals a "V"-shaped energy pit, consistent with experimentally observed cross-shaped fractures dominated by axial propagation and long-axis extension. This study conclusions can provide a theoretical basis for predicting and preventing coal-rock instability.