An examination of stress wave blasts deflection in materials that resemble rocks with soft and hard interlayers

This study employs the particle flow algorithm to simulate stress wave propagation across stuffed joints in a singlehole blasting scenario involving concrete with soft and stiff interlayers. Blasting was conducted at different depths, locations, and interlayer thicknesses, followed by analysis of the energy field and crack development. Results showed that shear fractures formed perpendicular to tensile cracks, which developed parallel to the blast hole. Increasing the hard interlayer's thickness enhanced its capability to accommodate concrete failure and reflect stress waves. The proximity of the weak interlayer to the blast hole influenced damage in the surrounding rock, with a threshold radius roughly twice the blast area. Outside this radius, the effects of blasting were minimal. For fixed weak interlayers, greater thickness led to more stress wave reflection and worsened concrete collapse. Lengthening weak interlayers improved stress reduction, while shortening them decreased the peaks of angular momentum and friction potential, increasing strain energy. In contrast, lengthening hard interlayers reduced effective stress dispersion and lowered both kinetic and friction energy peaks. The stress states of an object show that when a weak interlayer is within a radius of approximately twice the crushing area, the surrounding host concrete experiences high stress. In contrast, stress is low when the weak interlayer is outside this radius. When a hard interlayer is included, the host concrete is under high stress regardless of distance. The soft interlayer model exhibits higher kinetic and overall friction energy peaks compared to the hard interlayer model, but has a lower strain energy peak due to its significant dampening effect on wave propagation.