Non-complete relief method for measuring surface stresses in surrounding rocks
来源期刊：中南大学学报(英文版)2014年第9期
论文作者：ZHANG Feng-peng(张凤鹏) QIU Zhao-guo(邱兆国) FENG Xia-ting(冯夏庭)
文章页码：3665 - 3673
Key words：non-complete relief method; surface stress in surrounding rock; stress relief rate; ratio of initial principal stresses; ratio of released principal strains
Abstract: The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter (d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth (h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.
ZHANG Feng-peng(张凤鹏)1, QIU Zhao-guo(邱兆国)2, FENG Xia-ting(冯夏庭)1
(1. Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines
(Northeastern University), Shenyang 110819, China;
2. School of Science, Northeastern University, Shenyang 110819, China)
Abstract:The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter (d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth (h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.
Key words:non-complete relief method; surface stress in surrounding rock; stress relief rate; ratio of initial principal stresses; ratio of released principal strains
