Experimental and numerical study of blast-induced liquefaction in saturated calcareous sand sites

Calcareous sands are an important backfill material in artificial reef construction, and its stability under strong dynamic loads is crucial for ensuring the overall stability of reefs. Extensive studies on the seismic-induced liquefaction of calcareous sands have been conducted, but none have examined its characteristics of blast-induced liquefaction. Therefore, this study conducted a series of experimental and numerical investigations on the characteristics of blast-induced liquefaction in saturated calcareous sand sites. Field explosion tests were carried out on saturated calcareous sand sites with different scaled burial depths. Subsequently, liquefaction analysis models were constructed using the nonlinear dynamic analysis software LS-DYNA and were validated against measured stress waves. The numerical results indicated that the variation in pore water pressure (PWP) was consistent with the shock wave pattern, exhibiting a significant peak. Based on the numerical calculation results, empirical formulas for blast-induced liquefaction in saturated calcareous sands were established. Finally, the parameters analysis revealed that, under the same scaled burial depth, the stabilized PWP increased with the charge weight, and the liquefaction zone increased with the explosive charge. Under the same explosive equivalent, the accumulated area of excess pore water pressure (EPWP) decreased with the increase of explosive scaled burial depth. At the same scaled burial depth, the liquefaction impact range remained essentially the same across different charge weights. Enhancing the compactness of calcareous sands can improve its resistance to blast-induced liquefaction.