Rock dilation criteria development based on releasable strain energy

In order to overcome the problems that the calculation accuracy of current dilation criterion is not high and it is difficult for rock dilation to describe exactly the effect on the strain energy of the quake,based on the fact that en- ergy transformation is the essential attribute of material physical process,the existing dilation criterion is studied from the angle of elastic strain energy through theoretical analysis and experimental study,and a generalized dilation criteria are established accordingly. The results reveal that the Poisson’s ratio of 0. 5 is regarded as the premise of material di- lation of arbitrary stress state in the existing dilation criterion,and the influence of intermediate stress on dilation is not considered in the existing linear dilation criterion,and the stress of dilation increases linearly to confining pressure. Based on the analysis of the dilatancy criterion,a generalized dilatancy criterion is proposed to the energy point of view when the elastic strain energy reaches a critical value. The criterion breaks the rule that the traditional assumption that Poisson’s ratio is constant at 0. 5,and can reflect the influence of intermediate stress,elastic modulus,Poisson’s ratio and unknown releasable strain energy (or source releasing strain energy) on rock mass dilation. When Poisson’s ratio equals 0. 5,the criterion degenerate into the existing dilatancy criterion;when the stress level is the same,the smaller the Poisson’s ratio,the smaller the dilatancy stress calculated by the generalized dilatancy criterion;with the increase of the intermediate principal stress,the dilatancy stress calculated by the generalized dilatancy criterion may decrease. The generalized dilatancy criterion provides a theoretical support for earthquake prediction. It can not only calculate the dilatancy of rock mass affected by the strain energy released by the source,but also calculate the absorption strain energy of rock mass. The calculation of rock dilatancy stressed under triaxial tension and triaxial compression shows that the generalized dilatancy criterion can describe rock dilatancy characteristics,and the intrinsic mechanism of the above results is analyzed. The generalized dilatancy criterion can be used for rock dilatation,earthquake prediction,the mining of deep mineral resources and the stability evaluation of underground engineering.