Napier, JALMalan, DF2007-02-062007-06-072007-02-062007-06-071997-10Napier, JAL and Malan, DF. 1997. Viscoplastic discontinuum model of time-dependent fracture and seismicity effects in brittle rock. International journal of rock mechanics and mining sciences, vol 34 (7), pp 1075-10890148-9062http://hdl.handle.net/10204/1525http://hdl.handle.net/10204/1525A model is proposed for the direct mechanistic simulation of seismic activity and stress transfer effects in deep level mines. The model uses a discontinuum viscoplastic formulation to relate the rate of slip on a crack to the shear stress acting on the crack. A procedure is outlined for the solution of a collection of interacting cracks in a series of time steps and for the computation of energy changes in the crack assembly during each time step. Elastodynamic effects are not considered. In spite of the simplicity of the proposed slip law, it is shown that complex material behaviour can occur if the model is applied in a random assembly of cracks. A particular demonstration is given of the simulation of primary, secondary and tertiary creep phases in a uniaxially compressed sample containing an initial population of weak flaws. The model is next applied to the simulation of face advance steps in a deep level gold mine excavation and is shown to give favourable agreement between observed seismic activity and the length of fractures mobilized in a random mesh of cracks around the opening. The modelled closure between the excavation roof and floor, as a function of time, is also shown to be quantitatively similar to the observed field movements. A final example is given of the mining of a parallel-sided excavation at different rates which illustrates the tradeoff between high face advance and high seismic activity and low face advance but potentially greater damage in the rock near the stope.1770969 bytesapplication/pdfenCopyright: 1997 Pergamon-Elsevier Science LtdSeismic activitiesMining operationsViscoplastic displacement discontinuity methodArticleNapier, J., & Malan, D. (1997). Viscoplastic discontinuum model of time-dependent fracture and seismicity effects in brittle rock. http://hdl.handle.net/10204/1525Napier, JAL, and DF Malan "Viscoplastic discontinuum model of time-dependent fracture and seismicity effects in brittle rock." (1997) http://hdl.handle.net/10204/1525Napier J, Malan D. Viscoplastic discontinuum model of time-dependent fracture and seismicity effects in brittle rock. 1997; http://hdl.handle.net/10204/1525.TY - Article AU - Napier, JAL AU - Malan, DF AB - A model is proposed for the direct mechanistic simulation of seismic activity and stress transfer effects in deep level mines. The model uses a discontinuum viscoplastic formulation to relate the rate of slip on a crack to the shear stress acting on the crack. A procedure is outlined for the solution of a collection of interacting cracks in a series of time steps and for the computation of energy changes in the crack assembly during each time step. Elastodynamic effects are not considered. In spite of the simplicity of the proposed slip law, it is shown that complex material behaviour can occur if the model is applied in a random assembly of cracks. A particular demonstration is given of the simulation of primary, secondary and tertiary creep phases in a uniaxially compressed sample containing an initial population of weak flaws. The model is next applied to the simulation of face advance steps in a deep level gold mine excavation and is shown to give favourable agreement between observed seismic activity and the length of fractures mobilized in a random mesh of cracks around the opening. The modelled closure between the excavation roof and floor, as a function of time, is also shown to be quantitatively similar to the observed field movements. A final example is given of the mining of a parallel-sided excavation at different rates which illustrates the tradeoff between high face advance and high seismic activity and low face advance but potentially greater damage in the rock near the stope. DA - 1997-10 DB - ResearchSpace DP - CSIR KW - Seismic activities KW - Mining operations KW - Viscoplastic displacement discontinuity method LK - https://researchspace.csir.co.za PY - 1997 SM - 0148-9062 T1 - Viscoplastic discontinuum model of time-dependent fracture and seismicity effects in brittle rock TI - Viscoplastic discontinuum model of time-dependent fracture and seismicity effects in brittle rock UR - http://hdl.handle.net/10204/1525 ER -