Research On Three-dimensional HB Criterion Based On Releasable Strain Energ

After continuous development and improvement,the Hoek-Brown（H-B）strength criterion has gradually formed a relatively complete system.which has been applied to slope engineering,foundation engineering,underground engineering,mining engineering and other aspects with good effect.It has become the most widely used and most influential strength criterion so far,but there are still problems of different degrees.Based on the fact that the releasable strain energy is the inherent mechanism of rock mass failure,based on the generalized three-dimensional H-B rock mass strength criterion（GZZ criterion）proposed by L.Y.Zhang,a three-dimensional H-B rock mass strength criterion based on releasable strain energy（referred to as EH-B criterion for short）is established by combining theoretical research and experiments,and the EH-B criterion yield trajectory is modified.The main results are as follows:（1）The existing H-B strength criterion is mainly improved by improving the rock mass parameters and considering the influence of the intermediate principal stress,but there are relatively few studies on the H-B criterion from the perspective of energy.Based on the fact that the releasable strain energy is the inherent mechanism of rock mass failure,it is clarified that the physical meaning of the existing H-B strength criterion is not consistent with the inherent mechanism of rock mass failure,which is an important reason for its calculation accuracy and applicability to be improved.（2）Based on the fact that the releasable strain energy is the inherent mechanism of rock mass failure,it is clarified that the existing H-B strength criterion regards the Poisson’s ratio（?）constant as 0.5 when the rock mass fails under any stress level,which is not only the fundamental reason for the limited improvement of the calculation accuracy and applicability of the H-B strength criterion,but also the key to improving the calculation accuracy and applicability of the H-B strength criterion.（3）Based on the generalized three-dimensional H-B rock mass strength criterion（GZZ criterion）proposed by L.Y.Zhang,the three-dimensional H-B rock mass strength criterion based on releasable strain energy（referred to as EH-B criterion for short）is established by introducing material deformation parameters（?）_hb derived from elastic strain energy.（4）The theoretical analysis and experimental verification of the EH-B criterion show that:（1）The EH-B criterion is the inheritance and development of the GZZ criterion.It is a set of strength criteria with（?）_hb as a parameter,not a single strength criterion,when（?）_hb（28）0.5,it becomes the GZZ criterion;（2）The EH-B criterion not only avoids taking the Poisson’s ratio（?）constant as 0.5when the rock mass fails under any stress level,but also can utilize the existing research results of the H-B criterion,which is convenient for its application in practical engineering;（3）The true triaxial test verification shows that the calculation accuracy of the EH-B criterion is higher than that of the GZZ criterion,and the higher the accuracy of the GZZ criterion,the higher the corresponding the EH-B criterion.（5）Theπplane yield trajectory of the EH-B criterion does not satisfy the complete smoothness and convexity,and there are singular points.Three corner models（E-D,H-D and S-D）and the transformed principal stress method（T-S）are used to modify theπplane yield trajectory of the EH-B criterion,so that it can be directly embedded in numerical software for numerical simulation calculation.（6）Theoretical analysis and experimental verification of the modified EH-B criterion show that theπplane yield trajectories of the four modified EH-B criterion can maintain complete smoothness and convexity,which can be directly embedded in numerical software for numerical simulation calculation,and the calculation accuracy of the revised EH-B criterion is also higher than that of the GZZ criterion,and the average error can be as low as 2.75%.