135A
Underground construction methods
Surface subsidence, caving and rockbursts
932489 Tunnel bypassing Loearno - operation of a single stage reaming TBM (In German) Diethelm, W; Muter, T Felsbna VIO, N3, Sept 1992, P129-133
932493 Application of viscoelasticity to study the time-dependent surface subsidence caused by underground mining Zeng, Z; Kou, X F,ngng Geol V32, N4, July 1992, P279-284
A twin lane 4.8km long road tunnel in hard rock (mainly micaceous gneiss) is under construction in Switzerland. It is the first time a single-stage reaming TBM has successfully been used in a major project. Pilot diameter is 4.5m, reamed diameter 10.8m. The concept is outlined, machine design illustrated and technical details given, and progress to date described.
Mining subsidence is a dynamic process obeying mechanical principles. Attempts to describe dynamic subsidence using elasticity theory have been unsuccessful and an approach based on viscoplasticity is therefore presented. The physical meaning of the subsidence velocity factor (C) is interpreted and its relation to physical parameters of the rock mass established. It is now possible to evaluate C from results of laboratory or in situ tests. Comparisons are made of observed and calculated C values. Variation of C with size of tested object is found, which may explain variation in time factor with mining depth.
932490 Replacement laying of public and private house connection lines Uffmann, H P Proc 2nd International Symposium on Microtunaelling, Munich, 8 April, 1992 P19-22. Publ Rotterdam: A A Balkema, 1992 Replacement or renovation of leaking sewers is a legal requirement in Germany. Trenchless construction techniques have gained acceptance because of reduced disruption of surface activities. Pit-to-pit installation is described: guided drilling of a pilot tube, auger drilling to required diameter, then jacking of retrievable steel tubes followed by the sewer sections. Procedures for drilling from a starter pit to form an underground watertight connection with collector pipes are also illustrated.
Groundwater problems 932491 Enasun Tunnel of Chugo Expressway In: Rock Mechanics in Japan, Volume VI P93-95. Publ Tokyo." Japanese Committee for ISRM, 1991 The 8.Skm long tunnel through the Central Alps (maximum overburden 1000m) runs through faulted tuff and granite with high water table. Initial rock classification was by seismic refraction profiling and seismic fan shooting. Water pressures of up to 50bar were experienced, which led to debris flows into the pilot tunnel. A drain tunnel was needed for the pilot tunnel and additional drain tunnels were required in fault zones. Support (NATM with bolts) problems, which were greater than anticipated, are described.
932492 River bed poses problems for highway tunnel drive Crespo, A; Campo, E; Grasso, P; Russo, G; Pelizza, S Tuna Tunalg V24, N9, Sept 1992, P53-54 Part of the Frejus-Turin motorway runs through a 900m long tunnel beneath Mompantero in Italy. The tunnel runs almost entirely through schistose rock, but over a section of about 40m a sedimentary deposit, presumably of glacial river origin, was met. This consists mainly of pebbles and gravel and very high inflow rates were found. The tunnel was first stabilised and the fallout cavities filled. A two stage treatment with expansive polyurethane resins was used to construct a waterproofing ring around the tunnel. It was established that the initial hydrological equilibrium returned following the tunnelling.
932494 Simulation of rock- and gas outbursts (In German) Muller, W; Meiners, H Gluckauf-forsdumgsh V53, N1, Feb 1992, P16-20 Physical model tests and numerical simulation have been used to examine the operational conditions and rock mechanics factors influencing rockburst. In situ stress, strength of the seam and surrounding rock, gas content of the coal and mine layout are primary factors studied. Model tests involved drilling into coal blocks held in a special test rig and recording forces on the drill, volume of gas released, and relaxation of the sample. Material indicators obtained were used in numerical analysis. Pre-critical pressure deformation and the course of the outburst are simulated. 932495 Integrated analytical model of subsidence induced by level seam extractions Lin, S; Reddish, D J; Whittaker, B N Int J Geoteeh Geol Engng VIO, N3, Sept 1992, P203-221 An improved form of the subsidence influence function, based on stochastic theory in combination with variable functional parameters, is introduced. The discretisation technique of the finite element method is adopted to form the extraction elements which are used in integrated analysis of subsidence, horizontal displacement, strain, slope, and curvature. Results from the procedure are compared to those in the Subsidence Engineers' Handbook and with measurements made in UK coalfields. 932496 Modification of subsidence parameters for sloping ground surfaces by the rays projection method Shu, D M; Bhattacharyya, A K Int J Geoteeh Geol Engng VIO, N3, Sept 1992, P223-248 An analysis method has been developed to predict subsidence parameters on a sloping ground surface above a mined-out longwaU panel in an inclined seam. A rays projection method is used to calculate the subsidence components on the slope from corresponding components on an assumed equivalent horizontal surface passing through the mean elevation of the sloping surface. Variation of surface movement with slope angle can be studied. An illustrative example of application of the procedure is presented.
© 1993 Pergamon Press Ltd. Reproduction not permitted