Publication Abstract

not signed in
Log In
Title Enhanced spatial resolution of caving-induced microseismicity

Authors Reyes-Montes, J.M.Pettitt, W.Young, R.P.

Publication Reference Proceedings of the 5th International Conference and Exhibition on Mass Mining, Luleå, Sweden, 9-11 June 2008

Abstract Microseismicity provides a unique means for monitoring rock mass response to stress changes, in particular in non-accessible regions in the mining environment. Source location provides first order information that can be used in the interpretation of damage evolution and fracturing extension and orientation within the cave-back, which in turn provides information on the cave position, block sizing and mobility. The combination of in-situ microseismicity and numerical modelling using Synthetic Rock Mass models provide a robust method for understanding the factors controlling the behaviour and damage development within a jointed rock mass. This approach is specially of interest in volumes where it is not possible to obtain representative samples, such as in deep cave mines. Classical location routines are often based on the assumption of a homogeneous-isotropic medium that can be quite different to the velocity model generated by the presence of excavations. In particular, in block-cave mining at late stages of exploitation this can lead to higher uncertainties on the positioning of the cave-back based on microseismic location. To minimise this effect we use two different methods: relative location and ray-tracing using wavefront construction. Relative location minimises uncertainties by constraining the location to a small volume comprising the microseismic cluster, and is hence able to delineate fracture structures with higher resolution. In order to provide more accurate locations for the microseismic clusters, a more realistic velocity model is proposed consisting of a semi-ellipsoid void surrounded by layers of increasing wave transmission velocity. Travel times are then calculated by propagating wavefronts through the model. We show that through the combined use of these techniques we can both lower uncertainties in the absolute location of the seismic cloud and provide a higher resolution analysis of fracture structures. This allows the microseismic technique and structure analysis to be more accurately applied to projects where array coverage is reduced by the development of the cave void and damage zone.

Key Figure

Link http://massmin2008.com/projectweb/portalproject/Monday%209%20June.html



Return to publications list

< Return to the home page   ::  Contact Us
Applied Seismology Consultants