Abstract
The study of rock blasting failure pattern is of engineering importance. In order to investigate rock blasting failure pattern with one free boundary, high‐speed photography technology is introduced into the two‐dimensional granite model. Through high‐speed camera images, a crack that originated from spalling is observed and then propagates inward. By using the high‐speed digital image correlation method, the full‐strain fields on the surface of the specimens are calculated. The preliminary results show that von Mises strain localization appears on the specimen surface near the free boundary. The axial strains near that crack present three kinds of characteristics. There are the joint action areas of the strain localization by analyzing strains in different directions, and the strain localizations are related to the crack propagation. Ultimately, after analysis of the experimental results, the preliminary diagrammatic drawing of rock blasting failure pattern under stress wave action with one free boundary is drawn.
Highlights
Various experimental methods and laboratory-scale specimens have been employed to investigate the subsystem of free face effect on dynamic fracture initiation and propagation
From experimental and theoretical results on two-dimensional Plexiglas, Kutter and Fairhurst [3] concluded that a free boundary normally prefers the generation and extension of radial cracks when they propagate towards the surface
Via application of holographic interferometry on two- and three-dimensional specimens, Holloway [4] obtained clear photographs of radial cracks which emanate from the borehole region, and a radially orientated crack initiates at the free boundary and propagates inwards
Summary
It can be seen that dominant horizontal cracks formed by 100 μs and those cracks are known as spalling. Ere is a crack that originated from spalling and propagated inward by 250 μs. When an explosive detonates under a surface, blasting causes two types of waves—a Pwave and an S-wave. When the waves reach a free surface, four waves are caused [18]: (1) a reflected P-wave (PP-wave) due to the incident P-wave; (2) a reflected S-wave (SP-wave) due to the incident P-wave; (3) a reflected P-wave (PS-wave) due to the incident S-wave; (4) a reflected S-wave (SS-wave) due to the incident S-wave. According to the study of Fourney et al [19], when the reflection process has been
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