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.

Propagation characters of optical soliton in single-mode fiber is studied by using Bäcklund transformation. The results show that optical soliton pulse width broaden as excp(2Γξ) and the faster soliton speed is, the smaller soliton intensity decays because of fiber loss.