Abstract
Uneven floor and fragmentation play an important role in blasting operations due to the direct effects on the efficiency of hauling and loading. This paper focuses on the influences of initiation position on bench blasting in order to improve blasting effects. The numerical simulations of bench blasting at different initiation points (top, middle, and bottom) are implemented based on secondary development of LS-DYNA with a tensile-compressive damage model. The damage spatial distribution characteristics of different initiation points are compared. The outlines of rock foundation and boulder areas are analyzed with the damage threshold of critical breakage that is ascertained by acoustic characteristic of damage rock mass. Results of the numerical simulations demonstrate that different initiation points make a great influence on the stress and energy distribution in blasting process and induce different blasting effects. Middle initiation turns out to be the best initiation to increase the flatness of the floor and decrease the oversize boulder ratio simultaneously, which will increase the damage areas of the bottom and top regions and give a better blasting effect. Field experiment in Baihetan Station was carried out to validate conclusions of numerical simulation. Research could provide a good reference for the improvement of rock blasting.
Highlights
Bench blasting is the most widely used excavation method in mining, quarrying, and civil construction excavation
The cumulative damage of bench blasting is recorded with history variable hsv(i) based on the restart method in LS-DYNA, which may restart the simulation with a restart file and a restart input that define the changes to the model, including deleting contacts, materials, and elements
The characteristics of bench blasting with different initiation points are investigated with the numerical simulation using LS-DYNA and the field experiment in Baihetan Station
Summary
Bench blasting is the most widely used excavation method in mining, quarrying, and civil construction excavation. Hu et al [20, 21] made a conclusion of the widely used rock damage models and proposed the rock tensile-compressive damage model, which is used to simulate the blasting excavation damage zone of the high rock slope, and the result matched with the in situ measured data. The existing research achievements show that it is feasible to analyze the effects of bench blasting by the rock damage model. Some more researches indicate that there is a great influence of the initiation position on the explosive stress field [24, 25]. The superposition effects of explosive stress in cylindrical charge at different initiation points are analyzed. The processes of blasting in different initiation points are simulated based on the secondary development of the dynamic finite element code LS-DYNA.
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