Experimental and numerical study on ground shock propagation in calcareous sand

Surface explosion tests were conducted on calcareous sands to study the ground shock propagation in this medium. In the tests, ground shock at scaled distances between 0.33 m/kg1/3 and 1.46 m/kg1/3 was measured. After each explosion, the surface craters were observed and measured. The propagation and attenuation law of the peak pressure was derived according to the experimental measurement. The shock wave velocity and rise time were derived based on the pressure time-history curves. The empirical formula for pressure time-history curve of direct ground shock in calcareous sand induced by surface explosion was derived, and the predicted impulses showed good agreement with the experimental impulses. The indirect ground shock induced by air shock compression effect on the soil was discussed. Based on the field blast test results, validated numerical models were established to investigate the propagation of direct and indirect ground shock in calcareous sand. The attenuation law of peak pressure of indirect ground shock was then derived according to the numerical simulation results. Besides the surface explosion scenario, the contained burst cases were also modelled. The critical scaled depth of burial was derived as 1.3 m/kg1/3 in calcareous sand based on the surface crater and shock impulse.