Damage mechanism and spatial heterogeneity of loess subjected to explosion loading

The accelerated urbanization of the Chinese Loess Plateau has promoted the wide application of engineering explosion on the rapid excavation in loess regions. However, blasting in loess typically causes the various degrees of damage and failure to the remaining soil mass, compromising the bearing capacity and stability of the surrounding loess. Therefore, understanding the damage characteristics and microstructure changes of loess under explosion loading is essential for the construction of explosion projects in loess regions. In this study, the in-situ explosion experiment, dynamic triaxial tests, and micro-computed tomography (μ-CT) technology were employed to reveal the development characteristics of the blasting cavity, explore the dynamic properties of loess following the explosion, and visualize and quantitatively analyze the variation regulations of the loess microstructure. The results indicated that the shape of the blasting cavity was approximated as an ellipsoid. Explosion caused the breakage and rearrangement of particles and aggregates, significantly increasing the compaction of the loess mass, which promoted the evolution of loess dynamics properties towards high dynamic shear modulus and low dynamic damping ratio. In addition, the explosion loading significantly changed the size, number, morphology, and orientation of the loess pores, thereby causing a degradation in the pore network structure, and reducing its connectivity. Based on the spatial differentiation characteristics of the loess microstructure, the explosion zone outside the blasting chamber was divided into broken, plastic, and elastic zone. These findings provide valuable insights into the damage mechanism of loess under blasting loading.