Mechanical Study of Shear Failure of Vertical Goaf Drainage Hole

Geotechnical and Geological Engineering - Most of the published research on goaf-hole failures are performed using 2D numerical analyses. However, 2D analyses of the goaf-hole failure mechanism,...     

Numerical Study of Mine Site Specific Multiseam Mining and Its Impact on Surface Subsidence and Chain Pillar Stress

This paper investigates various multiseam mining related parameters using mine site specific data and numerical simulations. Two important mining effects—subsidence and stress—are analysed for different possible mining layouts. A geological mine dataset has been used to generate a numerical model. The predicted surface subsidence magnitude and surface profile have been compared under different scenarios to assess potential options in multiseam mining strategies. The effects that seam separation distances, mining offset, panel layout and panel orientation each have on surface subsidence and chain pillar stress magnitude have been investigated. The numerical simulation shows that ascending or descending mining directions have little impact on controlling the surface subsidence in multiseam mining and predicted an almost identical maximum stress development at the chain pillars. Numerical simulations infer that the orientation of the top panels control the subsidence profile.     

Mine Overburden Dump Failure: A Case Study

In any open cast mine, the management of stripped spoil during mining is crucial to the mine’s successful operation. The improper management of the overburden (OB) dump can result in stability issues which may affect safety and production of the mine. Various literatures have reported the failure of open pit dumps and the consequences in loss of life, production and impact on neighbouring amenities. Recently, the failure of an out-of-pit OB dump at an Indian Colliery was reported. The failed OB dump displaced spoil approximately 70 m from the original location of the dump toe and impacted on neighbouring amenities. This paper back analyse material properties and investigates the probable mechanism of this OB failure. Well established tools including limiting equilibrium and continuum numerical methods have been used to understand and identify the failure kinematics of this dump. It has been found that the residual friction angle of the material comprising the dump structural unit dominates stability. Mobilisation of residual strength can occur by operational induced strains and/or the presence of water. The shear strength of the foundation was fully mobilised and provided a slip surface for the overlying dump material. The resultant failure is manifest as a bilinear wedge movement of two ridged blocks defined by linear rupture planes.     

Assessment of Chock Capacity and Strata Caving for a Longwall Mine

A mine scale numerical analysis of modern day longwall using a 3D Cosserat continuum method has been presented. The effect of mine specific geological conditions on viability of introducing a modern day longwall is comprehensively investigated and analysed in this paper. The various longwall parameters like chock (face support) convergence and strata caving mechanism are evaluated. The varying thickness of the sandstone present in the roof can be seen to have a strong impact on the magnitude and pattern of chock convergence. The paper also discusses the performance of chocks with different capacities under identical conditions. The effect of overlaying sandstone properties and width of the longwall panels have also been investigated. The analyses carried out in this study is expected to provide valuable process guidance during the mine design in relation to selecting the optimal mine geometry and support capacity so that the potential mining hazards could be minimized.