The study of the damage effects resulting from the explosions of cylindrical charges holds significant importance in both military and civilian fields. In contrast to spherical charges, the explosive characteristics of the cylindrical charge exhibited spatial irregularities. To comprehensively quantify the influences of borehole diameter and buried depth on the damage effects, including the crater size and stress wave, experimental and numerical investigations on explosions induced by cylindrical charge are carried out in this paper. Firstly, a set of tests is conducted to provide fundamental data. Then, based on the meshfree method of Smoothed Particle Galerkin (SPG) and the K&C model, the variations in crater dimensions and the peak stress are fully simulated with a range of borehole diameters and buried depths. Finally, the influence of borehole and buried depth on the coupling factor is discussed. Both the buried depth and the borehole diameter impact the utilization of blast energy enormously. Furthermore, materials with distinct impedance values exert an influence on the distribution of the stress wave. Following the dimensional analysis, several empirical formulae expressing the crater size and peak stress are established, all of which can predict explosion damage rapidly and accurately.

It is important to study the effects of the mechanical properties and failure characteristics of defective frozen soil under coupled compression-shear loading for engineering construction safety and disaster prevention. In this study, the particle flow code was used to establish the distinct element method (DEM) model of a split-Hopkinson pressure bar experiment on frozen soil. The failure processes of frozen soils with different tilting angles and holes were simulated using the DEM model to investigate the influence of the tilting angle and hole deviation (deviation from the geometric center of the frozen soil specimen) on the impact mechanical properties and failure characteristics of frozen soil specimens under coupled compression-shear loading. The results of numerical simulation indicated that when the tilting angle and impact strain rate were 0 degrees and 100 s(-1), the axial peak stress of frozen soil specimen with a hole was smaller than that without a hole, the hole deviation had a minor influence on the axial peak stress. When the strain rate was 100 s(-1,) the axial and shear peak stresses of the frozen soil specimen without a hole increased and decreased, respectively, with increasing tilting angle, and the number proportion of shear-cracks also increased. When the tilting angle and strain rate were 60 degrees and 100 s(-1), the fully deviated hole had a minor influence on the impact mechanical properties and failure characteristics of the frozen soil. The impact loading also had a minor influence on the deformation of the hole.

Organic soil is often encountered in seasonally frozen areas in China. Before construction, the organic soil is required to be treated to improve its engineering performance due to the high moisture content and low bearing capacity. Cement and fly ash were adopted in this study to treat organic soil subjected to natural freeze-thaw cycles. The influences of freeze-thaw cycles on the stress-strain behavior and microstructure of cement and fly ash-stabilized organic soil (C-F-S-O-S) were evaluated using unconsolidated undrained triaxial (U-U), mercury intrusion porosimetry (MIP) and CT experiments. With and without freeze- thaw cycles, results indicate that the specimen with 20% cement and 5.0% fly ash content performed the best in strength and was selected to evaluate the influence of freeze-thaw cycles on C-F-S-O-S mechanical and microstructure characteristics. The strength, elastic modulus (E-M), cohesion, and internal friction angle of the specimen show the largest decrease of 9.27%, 13.97%, 3.45%, 5.19% after the first freeze-thaw cycle and then slow decreased with further increase of the number of freeze- thaw cycles. The strain corresponding to the peak stress increased with increasing freeze-thaw cycles, and the increase was the largest with a value of 10.19% after the first freeze-thaw cycle. Relationships between the number of freeze-thaw cycles and above parameters were established. A generalized model was also established to predict the stress-strain curve of the C-F-S-O-S. The applicability of the proposed model was validated with published experiment data. The specimen porosity increased first (by 11.03%) and then gradually stabilized after a series of freeze-thaw cycles as revealed by the MIP. Consequently, MIP and CT analysis reveals the soil structural variation since the freeze-thaw cycle is the main reason of the reduction of the specimen strength after the freeze-thaw cycle.