3D modeling of the influence of a splay fault on controlling the propagation of nonlinear stress waves induced by blast loading

Abstract

Risk assessment of the propagation of stress waves induced by blast loading is an important aspect engineering design and practice. Pre-existing geological structures affect the propagation of stress waves in the rock masses/strata. For homogenous materials, the wave energy scatters in the forms of wave reflection, refraction, diffraction, and mode conversion. The coefficient of absorption and scattering losses can help to understand the structural (joints, cracks, and large-scale faults) and physical properties (strength, lithology) of the rock masses/strata. Therefore, to explore the influence of interacting faults on the propagation of blast loading-induced stress waves, six 3D high-resolution numerical models were developed and run on with COMSOL Multiphysics software to test the influence of the Young's Modulus (E) of two pre-existing and interacting faults on the attenuation, superposition, and reflection of nonlinear stress waves. The results show that propagation of the stress waves through the domain in between the two faults amplified the stress energy. Moreover, and the stress wave intensity increased noticeably as they entered and left the tips of the interacting faults. The optimal propagation path of the stress waves lie within the materials whose E differ the least from that of the surrounding rocks. The fluctuation of the displacement along fault A was relatively large when the E of fault A was small (R = 0.1). The maximum strain energy density (SED) dropped by 84.2% from 3396 J/m3 to 536 J/m3 from the beginning tip to the middle domain of fault A; and further dropped by 28.9% as the waves traveled from the middle part to the tail of fault A. he reduction in the SED is in agreement to the power function (y = 3409x−0.406, R = 0.9994). The time interval (△FP) for having obtained the different △SED between the neighboring crest and trough of the frequency is significantly different. △FP yielded approximately 0.002, 0.0022 and 0.0325 s at an equal propagation distance from the beginning tip to the tail of the faults, respectively. This indicates that the energy loss during the first stage is large, and the stress wave decays quickly. This paper contributes significantly to our contemporary understanding of the attenuation, superposition, and reflection effects of the blast-loading induced stress wave propagation between the interacting tips of adjacent faults.