Deriving formulas of loading distribution on underground arch structure surface under close-in explosion

Abstract

Arch structure is one of the basic structural form used in underground engineering. Its load distribution under blasting load directly affects/determines its failure mode and damage grade. However, the experimental studies on this issue are currently limited, owing to the complexity and difficulty of the blasting experiments of underground structures. Therefore, in order to explore the propagation and distribution of blasting stress waves in concrete, comparative analyses, which are based on model test results of concrete target implosion, in view of fluid–solid coupling algorithm were firstly adopted. The reliability of numerical simulation algorithms was also verified. Then, the close-in blasting simulation calculations of the underground arch structure were performed using the verified numerical algorithm. The distribution law of the surface load of the underground arch structure was analyzed, and the time-history curves of overpressure and impulse at various points on the surface were obtained. Through the data normalization and fitting method, the load distribution function of structure surface is obtained, and a simplified prediction formula for predicting the vault point blast load parameters was established. Utilizing these formulas, a general method for determining the blast load at any point on the structure surface is proposed.