1、SEISMIC HAZARD EVALUATION IN UNDERGROUND CONSTRUCTION：THEORY AND PRACTICEPETER KAISERCentre for Excellence in Mining Innovation， Sudbury， Ontario， CanadaThe nature of Web systems is substantially different from more conventional software systems. They are developed in shorter timeframes， often act a
2、s the direct interface between multiple stakeholders， meet a more generic set of requirements， and generally serve a less specific user group. They are often developed very quickly from team. There is often considerable uncertainty on the part of the client as to their own requirements. The importan
3、ce of defining the objectives of the system during the early stages of a project are generally acknowledged to be important， but access to the tools and the templates can encourage developers to build too early. Often requirements are inadequately documented. or only emerge during development， or ch
4、ange as development proceeds.IntroductionThe keynote highlights recent developments in mining-induced seismicity research and development of procedures and tools for mine operators based on experience in the Sudbury Basin， Canada. The basin hosts major copper-nickel sulphide deposits that have been
5、minded since the early 1900， s. With over a century of mining， most operations are producing at greater depth where seismicity is a concern and seismic monitoring is now standard practice.Many mines and deep tunnels are plagued with strainbursts that are either triggered by seismic events or self-in
6、itiated due to stress concentrations near excavations. This topic will be covered in Part 1 for civil and mining applications. The rest of paper is divided into three parts dealing with structurally-induced seismicity and the procedures and tools developed to aid mine operators in dealing with seism
7、ic hazard through the use of Scismic Excavation Hazard Maps， and finally with integrated modeling approaches for mine-wide seismicity assessment.1、Stress Induced Seismicity-StrainburstsSelf-initiated rockbursts occur when the stresses near the boundary of an excavation exceed the rockmass strength a
8、nd failure proceeds in an unstable or violent manner. The stress deviator near an excavation increases as an excavation is advanced and eventually， particularly in brittle rock， fails with various degrees of energy release. During mining， the stress state is further disturbed and may lead to a furth
9、er stress increase and thus an increased strainburst potential. Finally， remote seismic events (e.g.，fault slip events) may add a dynamic stress component and thus trigger strainbursts. In addition， the rockmass strength may degrade with time or with loss of component， leading to sudden failure. In
10、either case the rockmass strength-to-stress ratio reaches unity and the rock fails. The failure process is sudden and violent if the stored strain energy in the rockmass is not dissipated by the supported rock near the excavation boundary. The strainburst potential is particularly high when the stif
11、fness of the loading system， i.e.， the mine stiffness， is lower (soft) than the unstable failure unloading stiffness of the volume of failing rock. The various causes of strainburst will be explained and guidelines for anticipated rock mass behavior prediction will be provided. 2、Mine Wide Seismic M
12、igration-Channel Element ModelMining-induced stress changes during excavation are generally associated with rockmass displacements， which are enhanced by chains of rotations of discontinuous rock mass blocks. These may lead to rockmass slip along pre-existing discontinuities or fracturing of massive
13、 or moderately jointed rock. As a result， seismic events not only occur in the rockmass near the boundaries of mine excavations or on excessively stressed geological structures； in deep mines， they can migrate far， at the mine-wide scale， from a triggering event. This type is more problematic and ma
14、y be destructive to mining production due to their apparently unpredictable characteristics. The concept of gravity-driven and thus displacement dependent mine-wide seismicity migration will be explored. A novel approach， the Channel Element Model (CEM)， based on rockmass displacement and chain-like
15、 rotational movement， will be introduced (Figure 1) and explored， CEM is a mathematical model that describes the time dependent migration and remote interactions from source disturbances. In contrast to mechanical contact interactions by the Discrete Element Method (DEM)， or constitutive relations b
16、y the Finite Element Method (FEM) to model near source disturbance responses， the CEM describes the phenomenon of gravity-driven displacement and thus stress and rockburst migration.Figure13、Scientific Visualization using Virtual Reality-Seismic Excavation Hazard MapsMIRARCO has pioneered the use of virtual reality (VR) technology for solving complex problems in the underground mining. The technology， first introduced for earth modeling in oil
