Rock bursts simulation with DDA:preliminary results
Rockbursts pose a great risk for deep underground excavations.Two different mechanisms are discussed in the recent literatures as possible triggers for rock bursts: 1)strain relaxation due to removal of opening material in highly stressed rock environments,2)energy redistribution induced by excavation related activities such as blasting.We develop in this paper an analytical expression for the change in elastic strain energy due to tunneling in a two dimensional continuous,homogeneous,linear elastic medium subjected to initial far field stresses.We find that the creation of underground circular opening results in increase of 1.7 times the initial strain energy of excavation in an annulus around the opening to a distance of three times the diameter of the tunnel,regardless of variables such as the radius of excavation,initial principal stresses and elastic modulus of the rock.We argue,therefore,that the annulus around the opening most affected by strain relaxation extends to a distance of three diameters from the tunnel center.The rockburst mechanism due to strain relaxation has been investigated by utilizing the energy budget associated with energy concentrations using the numerical DDA method.With increasing initial stresses,energy dissipation due to frictional sliding increases as well as the kinetic energy of the block system.We find that with decreasing frictional resistance of the block system(lower initial friction angle along pre-existing discontinuities)the sudden release of strain energy associated with tunneling is increased,resulting in stronger instantaneous shock energy which increases the likelihood for rockbursts.We believe that the systematic instantaneous strong shock energy of the blocks system as computed with DDA can model the temporal behaviour of micro-seismic energy monitored using acoustic emissions and/or geophones,in the field.
Y.H.HATZOR R.ZELIG B.G.HE X.T.FENG
Dept. of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, Isra State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechan
国际会议
The 12th International Conference on Analysis of Discontinuous Deformation(第12届非连续变形分析国际大会)
武汉
英文
15-23
2015-10-16（万方平台首次上网日期，不代表论文的发表时间）