Justification of safe distances in relation to surrounding objects during rock camouflage explosions

Abstract

Introduction. Despite the simplicity and accessibility of camouflage blasting, the issues of ensuring the safe conduct of such work are important. A camouflage explosion eliminates the occurrence of an air shock wave and the harmful effects of the explosion products on the environment, but leads to strong seismic vibrations. The impact of seismic loads on nearby objects can lead to the loss of their carrying capacity, damage and destruction, therefore, when choosing a place for installing camouflage charges, the task arises of assessing the field of environmental velocities during an explosion and determining the distances at which the velocities do not exceed the maximum allowable values established for objects under consideration. The aim of the study is to solve the problem of determining the velocity field in a continuous elastic-plastic medium during a camouflage explosion. Research methodology. The solution of the central symmetric problem of the propagation of explosive disturbances in solid media is based on the assumption that a deep spherical charge of a certain radius is placed in an unbounded half-space, which instantly turns into a high-pressure gas without changing the volume. It is assumed that the pressure in the cavity decreases according to a power law, and the relationship of pressure with the radius, velocity and acceleration of the expanding cavity is determined by the camouflage equation , whose constants A, B and C are functions of the parameters of rocks and soils. The perturbed state of the medium caused by the expanding cavity is also characterized by densities ρ0 and ρ respectively, in the elastic and plastic regions of its deformation, and the transition from the elastic state to the plastic state is accompanied by an instantaneous change in the density of the medium from ρ0 to ρ, introduced to approximately take into account the actual compressibility. Results. The determination of the velocity field in the medium surrounding the charge during the explosion is reduced to solving the ordinary differential equation of motion of a spherical cavity expanding due to internal pressure. It is shown that the unknown constant included in the obtained relation can be determined from the condition of conservation of the energy released during the explosion in the entire elastoplastic region of the medium motion. Discussion. The novelty of the result obtained lies in the substantiation of the possibility of using the assumptions about the vibrationless nature of the movement of the camouflage cavity and the incompressibility of the medium in the plastic and elastic regions to determine the velocity field that forms in a continuous medium during the explosion of a camouflage charge. Conclusion. Under the assumption of the vibrationless nature of the motion and the incompressibility of the medium in the plastic and elastic regions, a solution is obtained for the centrally symmetric problem of determining the velocity field in a continuous elastoplastic medium during a camouflage explosion. The solution obtained makes it possible to estimate the sizes of expansion zones, plastic deformation of the medium, and the impact of explosive disturbances on various objects.