Experimental study on fracture process in tight sandstone under pure shear based on digital image technology
The fracture process of tight sandstone under pure shear stress is key to understand the failure mechanism of tight sandstone.However,it has been controversial whether the initial cracks develop into mode Ⅰ or mode Ⅱ cracks under pure shear stress.This paper is based on the new optical measurement technology of digital image correlation(DIC)method and the theoretical method of double edge compression experiment.Double edge compression experiment was carried out,and then displacement and strain fields were obtained by the DIC method.The experiment results show that the double edge compression experiment can generate pure shear stress at the groove tip(prefabricated crack tip).The initiation process of tight sandstone specimens includes two stages of Type I cracks.The first stage cracks start from the groove tip and the second stage cracks start from the area connecting the two groove tips in the centre of the specimen.The research results of this paper provide new ideas for the application of digital imaging technology in the field of rock fracture mechanics.It has certain reference value for the analysis of the evolution law of pure shear fractures in tight sandstone during hydraulic fracturing.
万方数据
维普
