Abstract
In engineering blasting, the determination of the range of rock blasting fracture zone has important guiding significance for blasting construction. This paper proposes a method that can accurately and directly obtain the range of rock blasting fracture zone. Based on the theory of elastic wave propagation, test rods which are made of appropriate material are selected and prepared. A certain number of boreholes are drilled for subsequent insertion of the test rods along the direction perpendicular to the free surface of the excavation at a certain distance from the blast hole. Based on the field blasting test results, the deepest fracture position of the test rod is used as the boundary of the blasting fracture zone, and the range of the rock blasting fracture zone is obtained. A numerical analysis model is established according to the Mohr–Coulomb constitutive relationship and the Von Mises yield criterion. Then, the range of the fracture zone and the maximum horizontal radius of the fracture zone are analyzed and obtained. The numerical analysis results are compared with the field measured data. It is demonstrated that the range of the fracture zone obtained by the numerical simulation is in good agreement with the blasting test results of the pre‐embedded test rods. The research results can provide references for the safety control of blasting and excavation of rock slopes.
Highlights
Because blasting has the merits of fast excavation speed, high efficiency, and low cost, it has been widely used in the process of rock slope excavation and open-air pit mining
When the explosive explodes in the blast hole, a high-strength dynamic stress wave will be formed on the surface of the rock outside the blast hole, and the stress wave will propagate as an elastic wave in the surrounding rocks, producing crushing zones, fracture zones, and vibration zones [2]
In the area near the blast hole, the pre-embedded test rod was drilled along the direction perpendicular to the free surface of the excavation. e rupture depth of each test rod at different positions from the blast hole was obtained through the field blasting test, and the range of the rock fracture zone under the blasting load was obtained. e results will provide construction references for safe blasting excavation of rock slopes
Summary
Because blasting has the merits of fast excavation speed, high efficiency, and low cost, it has been widely used in the process of rock slope excavation and open-air pit mining. In the aspect of field testing, testing methods such as rock drilling acoustic wave testing and borehole television are widely used to determine the range of damage and tend to be convenient and efficient [14,15,16,17,18]. On the basis of previous research results, this paper attempts to propose a more accurate and intuitive test method to determine the range of rock blasting fracture zone. E rupture depth of each test rod at different positions from the blast hole was obtained through the field blasting test, and the range of the rock fracture zone under the blasting load was obtained. In the area near the blast hole, the pre-embedded test rod was drilled along the direction perpendicular to the free surface of the excavation. e rupture depth of each test rod at different positions from the blast hole was obtained through the field blasting test, and the range of the rock fracture zone under the blasting load was obtained. e results will provide construction references for safe blasting excavation of rock slopes
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