The Timpagrande umdergrour~ powerhouse, built between 1977 and 1978, was excavated in a highly fractured granite formation havirg poor mechanical properties. In this paper a description is given of the in situ and laboratory tests performed to characterize the rock mass, of the criteria adopted during the design stage to define the relevant geoteehnical parameters, of the methods used for the construction and of the system adopted to monitor the real behaviot~ of the structure. Final y, the results of a back analysis are presented, which attempt to identify the real values of the geotechnieal parameters of the rock mass on the basis of the control reBdings. Auth.
835158 TUNNELING UNDER COMPRESSED AIR IN MEXICO CITY Schmitter, J J; Rendon, R In: Soft-Ground Tumnelimg~ I~5-55. Publ Rotterdam: A. A. Bslkema, 1981 The paper describes the criteria used for the selection of air pressm'e for the stabilization of tunnels being constructed in soft clays unierlying Mexico City. The behavlour of the subsoil during tunnelllmg is also described. 835159 ~A'A'A3~W/NTS UPON SOFT-GROUND TUNNELINg: THEORETICAL SOLUTION Resemdiz; D; Romo, M P In: Soft-Ground Tunnelimgu P65-7~. Publ Rotterdam: A. A. Ba.lkema, 1961 Presents a t h e c r s t i ~ l sollltion fc~ settlements induced at amy d e p t h b y ttmnelllng in soft ground. The results are e~pressed in terms of parameters directly associated with excavation: initial state of stress~ stress-straln and strength properties of the soil, d e p t h add diameter of the tummel, fluid pressure on the face of the excavation and amount of radial yielding arc~md the tunnel. The solution accounts for the effects of s~ress release at the tunnel face and radial soll displacement arc~zl the tunnel.
In-situ stresses and stress around underground openings See also: 835160 835163 SLIP ZONES FOR DISCONTINUITIES PARATT~L TO CIRCULAR TUNNELS OR SHAFTS Daemen, J J K Int J Rock Mech Min Scl, V20, N3, June 1983,
m35-1~ An analytical solution is presented for determining the regions around a circular tunnel or shaft within which the strength is exceeded along discontinuities parallel or nearly parallel to the opening, ie the slip zone. The solution can be used to estimate the potential influence of weakness planes on tunnel stability and can assist in the design of rock reinforcement.
835160 STRESS PATH APPROACH FOR A TUNNEL DRIVEN IN STIFF CLAY Myriant~is, M L In: Soft-Oroumd Tunmeling, P79-8~. Publ Rotterdam: A. A. Balkema, 19~1 Describes the aE~lication of stress path principles to interpret the stress mobilisation in the ground surrou~ling a shield driven circular tunnel ~.l~m in diameter. The trammel was driven at a depth of 29.3m through overconsolidated stiff fiss~wed clay (London clay). The predicted pattern of stress paths a~rees well with in-situ meamm-e.merits of clay deformation arommd the tlmmmel. At the soffit a passive e a r t h l ~ e s m ~ e state prevails, while at axis level an active earth pressure regime d e v e l o p s .
835164 INSTANTANEOUS OUTBURSTS OF COAL AND GAS - A REVIEW Hargraves, A J Proc Australas Inst Min Metall, N285, March 1983, PI-37 The occurrence of instantaneous coal and gas outbursts in Australia is reviewed. Their magnitudes are small compared with those experiemced elsewhere. The proneness of seams depends on coal rank and seam gas composition. The proneness of places depends on depth, structure, intrusion ani tectonism amongst other factors. Methods of prevention, control and prediction of outburst are examined. 102 refs.
835161 FRESSURE-DXSPLACE~uav,' R~ATIONS IN TWO S Y ~ OF TUNNEL LINING Eisenstein, Z; Ei-Nahhasj F; Thomson, S In: Soft-Gronn~ Tummellng, P85-9~. Publ Rotterdam: A. A. Balkema; 1981 A tunnel in stiff silty clay till in Edmonton, Canadaj had two types of llni~g. A field monitoring prc~rsn~e provided performance data on the two t1~mel sIXPl~rt systems: a temporary lining of steel ribs and timber lagging followed by a permanent cast-in-place comcrete lining, Brad a precast comrete segmented lining. The fc~mer stabilized on a uniform radial pressure of 12 per cent of the overburden pressure and the latter had an elliptical pressure pattern with the vertical stress between ~5 ar~ 59 per cent and the horizontal stress between 27 and 36 per cent of the c~-erburden stress.
Power plants 835162 DESIGN
AND CONS'I~RUUTION OF THE TIMPAGRANDE POWerHOUSE Borsetto, M; GiusePl~-~ti~ G; Martinettij S Rock Mech Rock Emgr~, VI6, N2, June 1983,
~5-n5 RNI M
~'~',.CT OF OUTBURSTS OF COAL AND GAS ON DEEP MTNTNQ IN THE BCREN BASIN, QUEENSLANDj AND E~'~ORTS MADE TO DEAL WITH THE PHENOMENON. PART 3. THE DEVELOPMENT OF PP~DICTIVE M~T~ODS Roberts, I 0ueermland Gov Min J, VS~, N975, Jan 1983 , P12-19 Methods of outburst prediction are considered and gas emission studies are described. Consideration of geologic structures and the monitorirg of microseismic noise are also mentioned. The precautions which can be taken against outbursts such as induced firing, water infusion, lor~-hole gas drainage and the adoption of different methods of working are outlined. (For Part i see item 834140, for Part 2 see item
834139. ) 835166 RESEARCH
ON THE PREDICTION OF ROCKBURSTS AT WEaN DEEP LEVELS Brink, A V Z; O'Connor, D M J S Aft Inst Min Metall, V83, NI, Jan 1983, Pl-10