For underground chemical explosions in a cavity surrounded by uniform rock media, regularity of gas leakage was studied. Firstly, with method of dimensional analysis, influence physical quantities of gas leakage time, such as gas dynamic viscosity, overpressure of cavity, porosity of surrounding rock and ratio of the square of surrounding rock's thickness to permeability, were obtained. Qualitative functional relation of these quantities was proposed. Then, on the basis of Darcy's law, analytical formula for gas leakage time was derived. It agrees well with the qualitative functional relation derived with dimensional analysis method. Namely, two functions derived from totally different ways are highly compatible with each other. The method proposed is an enlightening idea and an efficient technique for theoretical analysis and regularity research of underground explosions gas leakage. It provides references for engineering estimation.

Two-dimensional axi-symmetric gas-solid two-fluid model was established. Under three conditions of source: E0/10,E0/100,E0/1 000 (initial energy per mass of gas),diminishing of gas energy and gas pressure caused by packing particles was studied. It shows that: With higher initial energy per mass of source kinetic and internal energy of gas is diminished by packing particles more quickly,gas fluid is close to stillness more quickly,gas pressure is decreased more quickly.

An operator splitting method is developed for numerical simulation of strong explosion fireball.In the approach the system is split into two parts.One part couples radiation and fluid in a hyperbolic subsystem.Another parabolic part evolves radiation diffusion and source-sink terms.We propose a numerical method for stiff source term.It shows that the method maintains efficiency and satisfies the needs of engineering.At last,spatial distributions of parameters in nuclear explosion reflecting fireball evolution are given.The calculation agrees well with empirical formulas.

To forecast gas leakage of a planned experiment,harmful gas leaking time from a scaled underground explosion cavity and ratio of leaked harmful gas to entire harmful gas are studied with theoretical analysis and numerical simulation.The leakage mechanisms are:(1) gas leaks through uniform porous media,(2) gas leaks through non-uniform porous media,(3) gas leaks through fractures.It shows that leakage time is proportional to two thirds power of explosive amount in scaled underground explosions.Percentages of leaked gas are approximately same for scaled explosions in same media.Theoretical results about leakage time is basically in line with scaled experimental results.

For evaluating damage of strong explosion,boundary conditions of coupled Eulerian-Lagrangian calculation are used.Energy accumulation due to radiative transfer is considered.Coupled methods of two-dimensional numerical simulation with cylinder symmetry are established,which calculate simultaneously equations of radiation hydrodynamics and hydro-elasto-plastic.Full physical processes of underground strong explosion are presented.They are propagation of radiation front in detonating room,transmitting of radiative energy to wall of detonating room,inward expanding of detonating room wall,propagation of shock wave in rock,compressing of high-pressure in detonating to room wall and outward expanding like waves of detonating room wall.

One-dimensional radiation hydrodynamics equations with spherical symmetry are used to study early development of fireball front and case shocks in strong explosion.Numerical method for radiation transport equations is established.The calculation results agree well with Brode's.Early formation of fireball front and case shocks in strong explosion at different yield,density in explosion zone and altitude are simulated numerically.Calculation results are analyzed.

Using high resolution TVD schemes and MacCormack schemes and two-phase gas-droplet conservation equations with 2D cylindrical symmetry in the Euler coordinate, it investigates the forming process of gas-droplet detonation and attenuating regularity of shock wave. The calculated results are in good accord with others.