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Underground support design using block theory to determine keyblock bolting requirements
100A formation and required support pressures were identified.
843181 Assessment of support requirements for a large excavation at depth Kersten, R; Piper, P; Greef, H In: Rock Mechanics in tile Design of Tunnels (papers to the Syml~simm, 26 August 1983) P41-46. Publ South Africa: ISRM South African National Group, 1983 The use of the uniaxial compressive strength in a design criteria for a large excavation in intensely bedded rock formations may lead to an underestimation of the stability. Following the construction of a plant room 2170m below surface at the Hartebeestfontein Gold Mine, South Africa, excessive sidewall displacement occurred. The original support system - anchored rock studs and grouted cables - was supplemented with additional grouted cables and convergence recordings showed a reduction in sidewall movement.
843182 Some considerations concerning the support of tunnels in deep mines Wagner, H In: Rock Meclu~ics in the Design of Tmmels (papers to the Syn~osinm, 26 August 1983) P51-59. Publ South Africa: ISRM South African National Group, 1983 The dominant mode of rock fracturing in deep mine tunnels sidewall slabbing and subsequent buckling of these slabs - can be controlled by rockbolt support. It is concluded that the initial stiffness of the supports and their spacing is more important than the support load. Support stiffness can be improved by increasing the cross sectional area of the bolts and reducing the effective tendon length by full column grouting. Under dynamic loading conditions eg rock bursts, support systems with high initial stiffness and good yield characteristics are required.
843183 Design for support for rockborSt-lWOnetunnels Ortlepp, W D In: Rock Mechanics in the Design of Tunnels (papers to the Symposium, 26 August 1983) P69-78. Publ South Africa: ISRM South African National Group, 1983 Examines the elements of rock reinforcement-type support, 'wire-mesh support', used in gold mine tunnels subject to rock burst damage. The material properties and behaviour during violent rock failure are discussed for: (1) short tendons - rock studs, shepherds crooks, grouted rope, (2) long tendons - multiple rope anchors, wire rope anchors, discard hoist rope, (3) lacing and (4) wire mesh. It is essential that elements of the support system should yield rather than fracture and in areas of seismic risk bond strength of tendons should be limited.
843184 Underground support design using block theory to determine keyblock bolting requirements Gen-hua Shi; Goodman, R E In: Rock Mechanics in the Design of Tunnels (papers to the Symposium, 26 August 1983) P81-105. Publ South Africa: ISRM South African National Group, 1983 Jointed rock is a tightly-fitting three-dimensional mosaic of polyhedral rock blocks created by intersecting discontinuities. Excavation of surface or underground space allows certain blocks to move and by using block theory it is possible to determine the most critical of these, denoted as keyblocks. Both individual, convex keyblocks and multiple, non-convex 'united' keyblocks are considered. By means of a worked example it is shown how to designate a keyblock and establish the area and bolt forces on the perimeter to prevent keyblock movements.
843185 Rock mass classification for block caving mine drift support Kendorski, F S; Cummings, R A; Bieniawski, Z T: Skinner, E H Proc 5th Congress of the International Society for Rock Mechanics, Melbourne, 10-15 April 1983 V1, PB51-B63. Publ Rotterdam: A. A. Balkema, 1983 The Modified Basic R M R System (MBR), based on an in-depth field study of several US caving mines, is proposed. The MBR is the first of three sequential ratings generated by the system and is a pure description of geological conditions. It is adjusted to obtain a rating useful for existing temporary, or development, support. In the final step, the adjusted MBR is again adjusted for final, production support ratings.
843186 Role of roof bolting in tail gates driven to the rise or to the dip of inclined seams (In Polish) Konopa, W Pr G1 inst Gorn Komunikat 724, 1982, 12P The loading and stability criteria for an inclined tail gate in relation to a longwall face are considered in three phases: (1) approach of the face; (2) passage of the face; (3) retreat of the face from the site under investigation. It is concluded that only in the first phase is independent roof bolting justified; in the second and third phases additional supports are indispensable as there is an almost quadruple increase in transverse force and a 2.5fold increase in bending moment. The asymmetric loading of the tail gate roof during the retreat of the face is analysed and is shown to explain the asymmetry of delamination of the roof observed in practice.
Groundwater problems 843187 Ground-water inflow in the Kaimai Rail Tunnel, New Zealand Davoren, A Bull Assoc Engng Geol V20, N4, Nov 1983, P387-391 Groundwater inflow created problems during the construction of the 8.8km Kaimai Rail Tunnel; drains were constructed to contain the water. A series of flow gaugings was carried out over a 6 month period to determine whether to grout and where to grout.
843188 Design of underground plugs Auid, F A lnt J Min Engng V1, N3, Oct 1983, P189-228 Reviews underground plug design and construction to control water inflow in underground excavations. Three case studies are included for illustration.
843189 Ground water pressure relief wells in shaft sinking Scott, R A; Daw, G P lnt J Min Engng V1, N3, Oct 1983.1Y229-236 The pattern of pressure relief produced in a confined aquifer by a ring of vertical relief wells is conventionally evaluated by summation of simple contributions from individual wells. Where the wells surround an open excavation such as a shaft, the pattern is modified. This paper outlines the appropriate modifications. The resulting pattern of pressure relief and of shaft inflow is calculated for typical practical situations for an open circular shaft and also for a shaft protected by an annular zone of grouted ground. The examples show the influence of number and location of relief wells and the degree of permeability reduction in the annulus. Auth.
843181 Assessment of support requirements for a large excavation at depth Kersten, R; Piper, P; Greef, H In: Rock Mechanics in tile Design of Tunnels (papers to the Syml~simm, 26 August 1983) P41-46. Publ South Africa: ISRM South African National Group, 1983 The use of the uniaxial compressive strength in a design criteria for a large excavation in intensely bedded rock formations may lead to an underestimation of the stability. Following the construction of a plant room 2170m below surface at the Hartebeestfontein Gold Mine, South Africa, excessive sidewall displacement occurred. The original support system - anchored rock studs and grouted cables - was supplemented with additional grouted cables and convergence recordings showed a reduction in sidewall movement.
843182 Some considerations concerning the support of tunnels in deep mines Wagner, H In: Rock Meclu~ics in the Design of Tmmels (papers to the Syn~osinm, 26 August 1983) P51-59. Publ South Africa: ISRM South African National Group, 1983 The dominant mode of rock fracturing in deep mine tunnels sidewall slabbing and subsequent buckling of these slabs - can be controlled by rockbolt support. It is concluded that the initial stiffness of the supports and their spacing is more important than the support load. Support stiffness can be improved by increasing the cross sectional area of the bolts and reducing the effective tendon length by full column grouting. Under dynamic loading conditions eg rock bursts, support systems with high initial stiffness and good yield characteristics are required.
843183 Design for support for rockborSt-lWOnetunnels Ortlepp, W D In: Rock Mechanics in the Design of Tunnels (papers to the Symposium, 26 August 1983) P69-78. Publ South Africa: ISRM South African National Group, 1983 Examines the elements of rock reinforcement-type support, 'wire-mesh support', used in gold mine tunnels subject to rock burst damage. The material properties and behaviour during violent rock failure are discussed for: (1) short tendons - rock studs, shepherds crooks, grouted rope, (2) long tendons - multiple rope anchors, wire rope anchors, discard hoist rope, (3) lacing and (4) wire mesh. It is essential that elements of the support system should yield rather than fracture and in areas of seismic risk bond strength of tendons should be limited.
843184 Underground support design using block theory to determine keyblock bolting requirements Gen-hua Shi; Goodman, R E In: Rock Mechanics in the Design of Tunnels (papers to the Symposium, 26 August 1983) P81-105. Publ South Africa: ISRM South African National Group, 1983 Jointed rock is a tightly-fitting three-dimensional mosaic of polyhedral rock blocks created by intersecting discontinuities. Excavation of surface or underground space allows certain blocks to move and by using block theory it is possible to determine the most critical of these, denoted as keyblocks. Both individual, convex keyblocks and multiple, non-convex 'united' keyblocks are considered. By means of a worked example it is shown how to designate a keyblock and establish the area and bolt forces on the perimeter to prevent keyblock movements.
843185 Rock mass classification for block caving mine drift support Kendorski, F S; Cummings, R A; Bieniawski, Z T: Skinner, E H Proc 5th Congress of the International Society for Rock Mechanics, Melbourne, 10-15 April 1983 V1, PB51-B63. Publ Rotterdam: A. A. Balkema, 1983 The Modified Basic R M R System (MBR), based on an in-depth field study of several US caving mines, is proposed. The MBR is the first of three sequential ratings generated by the system and is a pure description of geological conditions. It is adjusted to obtain a rating useful for existing temporary, or development, support. In the final step, the adjusted MBR is again adjusted for final, production support ratings.
843186 Role of roof bolting in tail gates driven to the rise or to the dip of inclined seams (In Polish) Konopa, W Pr G1 inst Gorn Komunikat 724, 1982, 12P The loading and stability criteria for an inclined tail gate in relation to a longwall face are considered in three phases: (1) approach of the face; (2) passage of the face; (3) retreat of the face from the site under investigation. It is concluded that only in the first phase is independent roof bolting justified; in the second and third phases additional supports are indispensable as there is an almost quadruple increase in transverse force and a 2.5fold increase in bending moment. The asymmetric loading of the tail gate roof during the retreat of the face is analysed and is shown to explain the asymmetry of delamination of the roof observed in practice.
Groundwater problems 843187 Ground-water inflow in the Kaimai Rail Tunnel, New Zealand Davoren, A Bull Assoc Engng Geol V20, N4, Nov 1983, P387-391 Groundwater inflow created problems during the construction of the 8.8km Kaimai Rail Tunnel; drains were constructed to contain the water. A series of flow gaugings was carried out over a 6 month period to determine whether to grout and where to grout.
843188 Design of underground plugs Auid, F A lnt J Min Engng V1, N3, Oct 1983, P189-228 Reviews underground plug design and construction to control water inflow in underground excavations. Three case studies are included for illustration.
843189 Ground water pressure relief wells in shaft sinking Scott, R A; Daw, G P lnt J Min Engng V1, N3, Oct 1983.1Y229-236 The pattern of pressure relief produced in a confined aquifer by a ring of vertical relief wells is conventionally evaluated by summation of simple contributions from individual wells. Where the wells surround an open excavation such as a shaft, the pattern is modified. This paper outlines the appropriate modifications. The resulting pattern of pressure relief and of shaft inflow is calculated for typical practical situations for an open circular shaft and also for a shaft protected by an annular zone of grouted ground. The examples show the influence of number and location of relief wells and the degree of permeability reduction in the annulus. Auth.