Testing method for mode I crack dynamic fracture overall process parameters under blast loading

Abstract

The invention, a testing method for mode I crack dynamic fracture overall process parameters under blast loading, discloses the testing method for the dynamic crack initiation toughness, dynamic expansion toughness and dynamic crack arrest toughness of mode I crack under blast loading, and belongs to the technical field of geotechnical engineering. The configuration of an internal single crack disc specimen with a large size is an autonomous design; testing results cannot be influenced by reflected extension waves and transmission waves; and the method is suitable for researching the crack growth rate and growth behavior of the whole process. Blast loading adopts an 8# detonator; numeral calculation adopts a finite element difference software AUTODYN; and a result basically accords with atest. A load stress time history curve can be input into a finite element program ABAQUS; the time history curve of a dynamic stress intensity factor can be obtained; and the dynamic fracture toughness of a material can be determined through the fracture time of a crack. The specimen is simple in configuration and easy in processing; the test is concise and clear in process and convenient in operation; and researches on crack dynamic growth behavior and tests on the dynamic fracture toughness can be realized.

Description

Technical field [0001] The invention belongs to the technical field of geotechnical engineering, and relates to a test method for the dynamic fracture toughness of a mode I crack under an explosive load with a high loading rate. Background technique [0002] In many rock mass projects, such as the construction of rock tunnels under mines, the excavation of mountain tunnels, the construction of subways and air defenses, etc., blasting has always been one of the main rock breaking methods. The main reason is that the blasting method is simple, economic and High efficiency and other advantages. However, our understanding of the blasting process is not deep enough. This is because explosives and rocks are relatively complex materials. The effect of blasting depends on the detonation characteristics of the explosive and the dynamic response characteristics of the surrounding rock mass. It is determined by detonation parameters, such as detonation pressure, detonation temperature, act...

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Problems solved by technology

Compared with the impact load, the peak value of the explosion load is larger and the loading rate is faster. Scholars have conducted fracture experiments on rock I-type cracks at four different loading rates: quasi-static, drop weight, light gas cannon, and explosion. The results show that the explosion The loading rate is much greater than the impact load, and the cracking time is shorter. Therefore, the study of rock fracture damage under blast load cannot be replaced by SHPB impact load, and its fracture toughness cannot be replaced by the test results under impact load.

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