Analysis of ground water seepage towards tunnels

PROPERTIES:GENERAL 953030 Effect of coal mining and coal based industrial activities on water quality of the River Domodar with specific reference to heavy metals R. K. Tiwary & B. B. Dhar, International Journal of Surface Mining, Reclamation & Environment, 8(3), 1994, pp 111-115. A study of water quality of the river Damodar in a stretch of 50 km in Jharia Coalfield region was carried out with specific reference to heavy metals. Sediments of the river bed was characterized for heavy metals, Fe, Mn, Cd, Cr, Ni and Pb to determine total carry over of heavy metals in the fiver body. Heavy metal concentrations in the river sediments were higher than in the river water. The deposition of Cr in sediment was higher downstream in comparison to other stretches. The study also showed that Fe and Mn were irreversibly retained in the sediment and this effect was also observed for other metals in decreasing order; Pb, Cr, Ni and Cd. (Authors) 953031 The identification of constituents in waste waters from gold mining using ICP-MS B. N. Noller, International Journal of Surface Mining, Reclamation & Environment, 8(3), 1994, pp 95-99. Gold mining has been undertaken in the Northern Territory, Australia since the 1870's. During the last 10 years, the use of the carbon-in pulp (CIP)/carbon-in-leach (CIL) process coupled with larger machinery to move material has permitted the mining of relatively low grades of ore and has created larger waste rock dumps than in the past. ICP-MS (inductively coupled plasma-mass spectrometry) has proved to be a particularly useful analytical tool for generating trace element patterns of waste rock materials and associated waste water. The predictive value of certain trace elements is demonstrated through a comparison of mine waste waters at different sites with uncontaminated surface and groundwaters. A comparison is also made with alluvial gold mining tailings where element are primarily in particulate forms. (from Author) 953032 Ground-penetrating radar monitoring of a controlled DNAPL release: 200 MHz radar M. L. Brewster & A. P. Annan, Geophysics, 59(8), 1994, pp 1211-1221. A controlled release of tetrachloroethylene was performed in a saturated, natural sandy aquifer to evaluate the effectiveness of various geophysical techniques for detecting and monitoring dense nonaqucons phase liquids (DNAPLs) in the subsurface. Radar sections collected at different times over the same spatial location clearly show the changes induced by the movement of DNAPL in the subsurface. Temporal changes can be examined through the evolution of a radar data trace collected at a single spatial location. Normal moveout analysis of common-midpoint data demonstrates induced changes in electromagnetic wave velocities of up to 30% caused by the presence of DNAPL. (from Authors) 953O33 Analysis of ground water seepage towards tunnels M. Atwa & E. Leca, in: Tunnelling and ground conditions. Proc. congress, Cairo, 1994, ed M.E.A. Salam, (Balkema), 1994, pp 303-310. The purpose of the work described in this paper is to analyze seepage towards tunnels under steady conditions by means of two-dimensional and three-dimensional t'mite element models. The influence of ground conditions, such as soil anisotropy and layered ground profiles on the water flows are analyzed for permeable tunnels and lined tunnels of finite permeabilities. The paper also considers the three-dimensional flow pattern towards the face of a tunnel under

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construction, with emphasis on the influence of soil anisotropy as well as the presence of a grouted soil mass at the face, on seepage towards the tunnel. (Authors)

Chemical and physical changes due to water 953034 Contribution of artesian water to progressive failure of the upper part of the Delhi Pike landslide complex, Cincinnati, Ohio R. L. Baum, US Geological Survey Bulletin, 2059-D, 1994, 14 pp. Artesian water under at least 1.5 m of pressure head occurs in limestone layers of weathered shale and limestone bedrock at the Delhi Pike landslide complex in Cincinnati, Ohio. The colluvium slips on an undulating failure surface that coincides approximately with the top of the weathered bedrock. A model of ground-water flow in ground beneath the slope indicates that seepage in the colluvium is nearly horizontal near the contacts with the limestone beds, but seepage may have a strong downward component away from the contacts. Analysis indicates that artesian water flowing from the limestone beds has no si~,nificant effect on the overall stability of the thin colluvium at Delhi Pike, and plays only a minor role in determining the positions of initial local failures that lead to progressive failure. (from Author)

PROPERTIES OF ROCKS AND SOILS General 953035 Rock mechanics and computational methods appfled to the design of a potash mine in Brazil A. M. Costa, P. C. D'Efia, L. C. Coelho, N. F. F. Ebecken & J. L. Queiroz, in: Applications of computational mechanica in

geotechnical engineering. Proc. workshop, Rio de Janeiro, 1991, ed E.A. Vargas & & others, (Balkema), 1994, pp 149209. This paper describes the application of rock mechanics and computational methods to the design of an underground potash mine at the state of Sergipe in Brazil. The need of an extensive rock mechanics research program is due to the lack of knowledge about the mechanical behavior of tachyhydrite, a special evaporite, which underlies the orebody in the evaporitic basin. Tachyhydrite is an evaporite composed of magnesium chloride, calcium chloride and 12 molecules of water (MgCi2 CaCl2 12H20), whose mechanic resistance is approximately 20 times as low as the other evaporite that constitute the host rock. Its creep is much higher than the other evaporites and it also presents a high hygroscopy. The investigation of constitutive laws for the evaporites is discussed, with emphasis given to Tacliyhydrite, analysis of instrumentation remits and the application of the finite element method in the design of the mining structure overlaying the Tachyhydrite layer. (Authors) 953036 Coal preparation differs in South Africa D. Horsfall, Coal, 99(10), 1994, pp 92-93. South Africa's coal industry depends on highly efficient coal preparation plants. The deposits contain large percentages of mineral matter which are difficult to remove. This article gives details of these impurities and compares the preparation methods used with those in Europe and North America. (S.E.Long)