Method for Calculating the Pressure of Oblique Reflection of Shock Waves at the Water-Soil Interface

The theoretical framework for calculating the oblique reflection pressure of shock waves at the soil-water interface remains incomplete. In this study, building upon previous theoretical derivations, we established an analytical equation for the oblique reflection pressure of shock waves at the soil-water interface. Based on this, we conducted underwater explosion tests and developed a fluid-structure interaction numerical model, using the experimental data to validate both the theoretical model and the numerical model. To investigate the influence of different parameters on the normal reflection pressure coefficient, explosions were conducted using explosives with varying TNT equivalents at a distance of 0.52 m from the water-soil interface (with a proportional blast distance ranging from 0.326 to 2.936 m/kg¹^/³). Based on the incident pressure obtained from empirical formulas for underwater explosions, the calculated normal reflection pressure coefficient ranged from 1.26 to 1.50. At a distance of 0.3 m from the water-soil interface, with the air content of saturated soil varying between 0% and 10%, the reflected pressure ranged from 64.15 to 81.77 MPa, and the reflected pressure coefficient ranged from 1.19 to 1.52. To investigate the influence of different parameters on the oblique reflection pressure calculation model, the results of numerical simulations with varying blast distances and incident angles (0°-40°) were analyzed, clarifying the applicability range of the theoretical model: When the incident angle is ≤20°, the model’s prediction error is generally below 10%, demonstrating high engineering accuracy; when the incident angle is >30° and the blast distance is small, the model error increases significantly, providing clear boundary conditions for practical applications. The derived calculation method for the shock wave reflection pressure at the water-soil interface has clear physical significance and high computational accuracy, providing a theoretical foundation for assessing the damage caused by underwater explosions to engineering structures in subaquatic soil.