Optimum Layout of Underground Explosives Storage Chambers - Case Study: Underground Explosives Storage of Bakhtiary Dam Project

If layout of underground storage of energetic materials such as explosives¡ gases and petroleum designed inappropriately¡ an unexpected explosion can result in transmission and spread of the explosion to other adjacent underground spaces and causing catastrophic events both in surface and underground. In this paper a calibrated elasto-plastic numerical model in FLAC3D software is used to simulate the underground storage explosion. The peak particle velocity (PPV) damage criterion and the plastic deformation criterion were adopted to study the extent of damage zone around the explosion. The results show that the extent of damage measured based on the PPV criterion is larger than the plastic deformation criterion. Investigating responses of concrete lining supports shows tensile ruptures in the concrete due to reflection of stress waves from inner walls¡ which can cause transmission of explosion without direct contact of damage zone to the nearby storage chamber. Finally¡ in this paper the safe separation distance and embedment depth is proposed for three underground explosives storage chambers of Bakhtiari Dam project.
Summary: In this paper¡ the explosion of underground storage facilities are modeled numerically using Flac3D software and it is tried to find the optimum layout of the underground facilities based on the extension of the explosion damage zone in numerical simulations.
The main purpose of this research is the use of numerical modeling in prediction of safe separation distance and embedment depth for energetic materials underground storage chambers¡ to prevent transmission of explosion between chambers.
Methodology and Approaches: In this paper¡ major features of chambers and surrounding rock mass have been numerically simulated using 3D finite difference method. The damage extension around the exploded chamber is evaluated using two criteria of critical PPV and Mohr-Coulomb failure criterion. The results of numerical simulations are compared with international standards.
Results and The results have proved that due to explosion stress waves reflection from inner walls of adjacent chambers that causes tensional cracks in concrete supports and adjacent rock mass it is necessary to simulate the presence of adjacent chambers in the numerical models. Results of simulations in different rock masses show that in strong rock masses¡ the extension of the damage zone is lower than week rocks¡ while due to lower attenuating ability of strong rock masses¡ the energy of stress waves propagating with in it is high and vice versa.