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Water decoupling blasting is an efficient method that can significantly improve blasting effects. A three-dimensional (3D) numerical investigation is conducted using the multimaterial Arbitrary Lagrangian Eulerian (ALE) method to deepen the understanding of the method. The blasting effects and pressure attenuation regularities for coupling, air and water decoupling blasting are compared to reveal the fracture mechanism for water decoupling blasting. The simulated results indicate that water is desirable to transmit blasting pressure, because it slows the blasting pressure attenuation and improves the blasting effect. Quantitative analysis of the radial, axial, and radial–axial decoupling charges is performed to optimize the charge structure. The radial decoupling charge is a better charge structure, which results in a more uniform blasting energy distribution. With the increase in the radial decoupled coefficients, the blasting pressure attenuation index first decreases and then increases. The analysis results indicate that 1.5 is the optimal radial decoupling coefficient, which can achieve the highest energy utilization efficiency. The simulated results for radial–axial decoupling blasting show that the rock failure regularities of radial or axial decoupling blasting exist in radial–axial decoupling blasting. By comparing the blasting effect of four commonly used explosives, trinitrotoluene (TNT), which has high blasting pressure, detonation velocity, and initial internal energy density, is the optimal explosive in water decoupling blasting, which is different from coupling blasting. [ABSTRACT FROM AUTHOR]

• A plastic Stillinger-Weber potential for soft rocks is proposed. • The plastic fracture behavior of soft rocks is effectively simulated. • The dependence of simulation results on mesh size is effectively mitigated. • Influence factors on the failure behaviors of soft rock tunnels are investigated. Soft rocks present some undesirable behaviors, such as low strength, high plasticity and softening. These traits pose challenges in the design and construction of soft rock tunnels. To address these issues and model plastic fracture behaviors of soft rocks, we proposed a plastic Stillinger-Weber (PSW) potential and integrated it into the discretized virtual internal bond (DVIB) model. The PSW-DVIB model combines the strengths of the plastic DVIB and the SW-DVIB models. It not only effectively reproduces the plastic fracture behavior but also accurately reflects the Poisson's ratio. Moreover, due to the inclusion of fracture energy in the PSW potential, the simulation results are basically mesh size independent. The PSW-DVIB model is then utilized to investigate the failure behaviors of soft rock tunnels. The effects of the coefficient of lateral pressure, in-situ stress, Poisson's ratio and tunnel shape on tunnel failure are investigated. The simulated results indicate that the coefficient of lateral pressure has significant influence on the failure zone distribution of the surrounding rock. With the coefficient of lateral pressure increasing, the failure degree of surrounding rock decreases firstly and then increases. The optimum coefficients of lateral pressure for the stability of circular, arched and square tunnels are about 1.00, 0.75 and 0.75, respectively. When the in-situ stress or Poisson's ratio is larger, the influence of the coefficient of lateral pressure on tunnel failure is more obvious. The influence of the coefficient of lateral pressure on square tunnels are more significant than the arched tunnels, and then the circular tunnels. These findings provide valuable insights for the design and construction of soft rock tunnels. [ABSTRACT FROM AUTHOR]