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Tunnel portal in adverse geological formations
347A 896468 Excavation in very difficult rock conditions (In German) Tschada, H; Schneider, E Proc Symposium on Rock Mechanics and Power Plants, Madrid, 12-16 September 1988 VI, P413,418. Publ Rotterdam: A A Balkema, 1988 Austrian standards for TBM driving are outlined. Excavation of the upper 8kin of the 22.5km pressure tunnel for a hydropower scheme is described. A standard TBM was used with maximum performance of 85m per day in good rock conditions. After 5kin, mica schists of very poor quality were reached, causing reduced advance rates. Frequent rockfall also reduced advance rate. Methods of support are described.
896469 Tunnelling in pumped storage development Ferreira, A; Karadi, G M Proc lnternatiomd Symposium Tunnelling for Water Resources and Power Projects, New Delhi, 19-23 January 1988 V], P175-180. Publ New Delhi: Oxford and IBH Publishing Co, 1988 Unique problems and their solutions encountered during design and construction of 3 pumped storage projects are described. At Northfield Mountain, a newly developed procedure was used for construction of shaft and tunnel. At Bad Creek, a pilot tunnel was excavated for in situ testing for design of power house orientation in an area of potential geotechnical problems. At Bath County, unacceptable leakage levels during initial infilling were overcome using high pressure grouting, expanded drainage and continuous monitoring.
896472 P~eters
of a tunnel boring machine's daily performance (In
German) Kohlbeck, F; Klingler, A Felsbau V7, N2, May 1989, P78-83 Advance, power and pressure of a TBM and rock mechanical and physical properties were monitored during the drivage of the 7600m Zillergrund hydro tunnel in mainly gneissic rock in Austria. Strong correlation is found between pressure and advance, and negative correlation between advance and power input. No correlation is evident between pressure and power input. 896473 Geotechnical assessment of the bearing capacity of coal mine floors Afrouz, A; Hassani, F P; Scoble, M J int J Min Geol Engng V6, N4, Dec 1988, P297-312 Three longwall faces with variable strata and mining conditions and supported by hydraulic chocks were studied. Beating capacity tests along the faces were conducted to evaluate the factors influencing floor deformation and failure. The effect of size, shape and perimeter of the base plates, thickness of the floor layer, time, and moisture on the ultimate bearing capacity of the floor was measured and discussed. The work may be applied to prediction of stability and support performance of face ends, as well as design of support systems and ground control on production faces. 896474 Infinite boundary elements Beer, G; Watson, J O lnt J Num Meth Engag V28, N6, June 1989, P1233-1247
896470 Tunnel portal in adverse geolngieal formations Madhavan, K; Sundara Babu, T D; Kumar, N Proc International Symposium Tunnelling for Water Resources and Power Projects, New Delhi, 19-23 January 1988 V1, P187-191. Publ New Delhi." Oxford and [BH Publishing Co, 1988
Special types of boundary elements are discussed which can be used for the modelling of surfaces which extend to infinity. The theoretical background and details of implementation are discussed. On test examples it is shown that the elements perform extremely well even for cases in which they are located close to the area of interest. A practical application of the use of the elements for the modelling of mining excavations is given. Auth.
Construction of the tailrace tunnel for the Mahi Bajaj Sagar Hydel project encountered problems when it intersected a saturated graphite schist band near the portal. Failure occurred and a chimney formed. Remedial measures entailed a steel frame false portal, backfilling the chimney with concrete, and remaining excavation using the forepoling technique.
896475 Stability and design of yield pillars located at shallow and moderate depths Ozbay, M U J S Aft last Min Metall 1/89, N3. March 1989, P73-79
Mines See also: 896186, 896249, 896267, 896275
896471 Chamber stoping at Loraine gold mines Steenkamp, J C; Ras, D J R M Assoc Mine Mangr S Aft, Circ N3, Nov 1988, P28-38 Chamber stoping was introduced for extraction of closely spaced, near horizontal reefs in geology complicated by faults with large displacements. Hangingwall and sidewall stability were considered for design of excavation size, resulting in 4 stopes separated by pillars. Support of the hangingwall was by rebar rods and prestressed cables, with mesh or steel strapping used in 3 of the chambers.
Pillar stability is analysed on the premise that pillars shed load in a stable manner if the slope of the strata load-deformation curve is steeper than that of the pillar in the post-peak regime. Local, mine structural and critical stiffnesses are discussed. Boundary element programs MINSIM-D and MINAP are used to model various pillar layouts using available data on pillar behaviour. Strata stiffness, and thus stability, is seen to increase as span to depth ratio, number of pillars, and percentage extraction decrease. Stability becomes unaceptably low when span exceeds about 5x depth. Stability is difficult to achieve if all pillars are in the post-peak state. 896476 Methane drainage in Iongwall coal mining De Villiers, A W J S Aft last Min Mettdl V89, N3, March 1989, P61-72 Methane emission during mining is influenced by methane content of the coal measures rocks, and rate of mining, which alters the stress field and fracturation, and hence permeability to the flow of methane. Methane emission into the goal is
© 1989 Pergamon Press pie. Reproduction not permitted R.M.M.S. 2616---T
896469 Tunnelling in pumped storage development Ferreira, A; Karadi, G M Proc lnternatiomd Symposium Tunnelling for Water Resources and Power Projects, New Delhi, 19-23 January 1988 V], P175-180. Publ New Delhi: Oxford and IBH Publishing Co, 1988 Unique problems and their solutions encountered during design and construction of 3 pumped storage projects are described. At Northfield Mountain, a newly developed procedure was used for construction of shaft and tunnel. At Bad Creek, a pilot tunnel was excavated for in situ testing for design of power house orientation in an area of potential geotechnical problems. At Bath County, unacceptable leakage levels during initial infilling were overcome using high pressure grouting, expanded drainage and continuous monitoring.
896472 P~eters
of a tunnel boring machine's daily performance (In
German) Kohlbeck, F; Klingler, A Felsbau V7, N2, May 1989, P78-83 Advance, power and pressure of a TBM and rock mechanical and physical properties were monitored during the drivage of the 7600m Zillergrund hydro tunnel in mainly gneissic rock in Austria. Strong correlation is found between pressure and advance, and negative correlation between advance and power input. No correlation is evident between pressure and power input. 896473 Geotechnical assessment of the bearing capacity of coal mine floors Afrouz, A; Hassani, F P; Scoble, M J int J Min Geol Engng V6, N4, Dec 1988, P297-312 Three longwall faces with variable strata and mining conditions and supported by hydraulic chocks were studied. Beating capacity tests along the faces were conducted to evaluate the factors influencing floor deformation and failure. The effect of size, shape and perimeter of the base plates, thickness of the floor layer, time, and moisture on the ultimate bearing capacity of the floor was measured and discussed. The work may be applied to prediction of stability and support performance of face ends, as well as design of support systems and ground control on production faces. 896474 Infinite boundary elements Beer, G; Watson, J O lnt J Num Meth Engag V28, N6, June 1989, P1233-1247
896470 Tunnel portal in adverse geolngieal formations Madhavan, K; Sundara Babu, T D; Kumar, N Proc International Symposium Tunnelling for Water Resources and Power Projects, New Delhi, 19-23 January 1988 V1, P187-191. Publ New Delhi." Oxford and [BH Publishing Co, 1988
Special types of boundary elements are discussed which can be used for the modelling of surfaces which extend to infinity. The theoretical background and details of implementation are discussed. On test examples it is shown that the elements perform extremely well even for cases in which they are located close to the area of interest. A practical application of the use of the elements for the modelling of mining excavations is given. Auth.
Construction of the tailrace tunnel for the Mahi Bajaj Sagar Hydel project encountered problems when it intersected a saturated graphite schist band near the portal. Failure occurred and a chimney formed. Remedial measures entailed a steel frame false portal, backfilling the chimney with concrete, and remaining excavation using the forepoling technique.
896475 Stability and design of yield pillars located at shallow and moderate depths Ozbay, M U J S Aft last Min Metall 1/89, N3. March 1989, P73-79
Mines See also: 896186, 896249, 896267, 896275
896471 Chamber stoping at Loraine gold mines Steenkamp, J C; Ras, D J R M Assoc Mine Mangr S Aft, Circ N3, Nov 1988, P28-38 Chamber stoping was introduced for extraction of closely spaced, near horizontal reefs in geology complicated by faults with large displacements. Hangingwall and sidewall stability were considered for design of excavation size, resulting in 4 stopes separated by pillars. Support of the hangingwall was by rebar rods and prestressed cables, with mesh or steel strapping used in 3 of the chambers.
Pillar stability is analysed on the premise that pillars shed load in a stable manner if the slope of the strata load-deformation curve is steeper than that of the pillar in the post-peak regime. Local, mine structural and critical stiffnesses are discussed. Boundary element programs MINSIM-D and MINAP are used to model various pillar layouts using available data on pillar behaviour. Strata stiffness, and thus stability, is seen to increase as span to depth ratio, number of pillars, and percentage extraction decrease. Stability becomes unaceptably low when span exceeds about 5x depth. Stability is difficult to achieve if all pillars are in the post-peak state. 896476 Methane drainage in Iongwall coal mining De Villiers, A W J S Aft last Min Mettdl V89, N3, March 1989, P61-72 Methane emission during mining is influenced by methane content of the coal measures rocks, and rate of mining, which alters the stress field and fracturation, and hence permeability to the flow of methane. Methane emission into the goal is
© 1989 Pergamon Press pie. Reproduction not permitted R.M.M.S. 2616---T