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The presence of groundwater in surface mining operations often creates serious problems. The most important is generally a reduction in stability of the pit slopes. This is caused by pore water pressures and hydrodynamic shock due to blasting which reduce the shear strength and seepage pressures, water in tension cracks and increased unit weight which increase the shear stress.
Examples of mine dewatering techniques at an open pit mine Open Pit Dewatering Techniques Inpit pumping This is the simplest mine dewatering approach, with potentially the lowest capital costs. rock is of such low hydraulic conductivity that pore water pressure reductions are very slow. Drainage of pit
Pore water pressure can cause uplift force and reduce the levels on the stability of coal mine slopes in depressurisation systems for two large open pit copper mines in
Water pressure acting in the pore spaces, fractures or other discontinuities in the materials that make up the pit slope will reduce the strength of those materials. Choice of correct analysis technique depends on both site conditions and the potential mode of failure, with careful consideration being given to the varying strengths, weaknesses and limitations inherent in each methodology .
design of piezometers, data collection and use of the pore pressure data are presented. 1. Introduction It is commonly accepted that ground water has a detrimental effect upon mining. The presence of ground water in and around an open pit excavation affects mining by reducing the
Journal Article: Porewater pressure in the roof of an underground mine in Illinois
Pore water pressure (sometimes abbreviated to pwp) refers to the pressure of groundwater held within a soil or rock, in gaps between particles ().Pore water pressures below the phreatic level of the groundwater are measured with vertical pore water pressure distribution in aquifers can generally be assumed to be close to hydrostatic.
Table amp; Pore Water Pressure In Deep Excavations #183; We excel through experience and learning #183; Version 0 2, Jul 201 3 01 Keywords Perforated standpipe, standpipe piezometer, groundwater table, groundwater movement, excess pore water pressure, hydraulic instability Synopsis In deep excavations, it is imperative to understand the
practice in open pit mines. The application of sound geotechnical engineering practice is considered to be an integral component of Part 2 of the Mines Safety and Inspection Act 1994 (MSIA). It is emphasised that this guideline is not totally inclusive of all factors concerning the application of geotechnical engineering in open pit mining.
#0183;#32;Guidelines for Evaluating Water in Pit Slope Stability is a comprehensive account of the hydrogeological procedures that should be followed when performing open pit slope stability design studies. Created as an outcome of the Large Open Pit (LOP) project, an international research and technology transfer project on the stability of rock slopes in open pit mines, this book expands on the
#0183;#32;Effects of Ground Fracturing with Horizontal Fracture Plane on Rock Breakage Characteristics and Mine Pressure Control Authors (first, second and last of 4)
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#0183;#32;The pore network at the highest threshold pressure (point ) has a porethroat diameter coincidently located within the range m in the distribution of porethroat diameters of the core sample (Fig. S3a''), which accounts for the majority (%) of pore volume; while the other two lower threshold pressures (point and ) at and m only account for % of the total
#0183;#32;Also, the water can be injected into the coal pores in a short time, preventing water from weakening the coal due to longperiod immersion, as the coal usually contains some clayey content. After saturation, the porosity was quickly measured using NMR and then uniaxial cyclic compressive tests were performed immediately to minimize a reduction in pore water pressure.
A Coal Mine Dump Stability Analysis an important aspect of designing large open pit mines. The majority of slope stability analyses performed in . tion due to rise in pore water pressure leads to the failure. Consolidation and compaction is another key factor be
THE EFFECTS OF GROUNDWATER PRESSURE The effects of groundwater pressure upon stress distributions within a slope have been explained in many publications, Hoek and Bray (1977), CANMET (1977) for example. Two main effects have been identified; a) Increased disturbing forces linked to cleft water pressure.
Pore water pressure reduction (depressurization around open pit slopes, pit bottoms and shafts and roadways). This is a more subtle objective which recognizes that high pore water pressures can have a significant destabilizing effect on slopes and underground openings, not only in unconsolidated deposits and soft rocks, but also in fractured hard rocks.
Above studies demonstrate the effects of moisture on strata control in coal mines and mine openings. Further, they reveal the necessity to find support systems to ensure safe operations in underground coal mines. As the case studies reveal, in the mines in Malawi, it is likely that the roof rocks are weakened and then fall as a result of humid air.
u Pore water pressure U Normal force exerted by pore water pressure on base of slice W Sandstone, coal, chalk, shale the geology, vegetation, the effect of intense rainfalls, or the effect of the facing direction of a slope (
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