843130 Hydraulic fracturing of coal seams for underground gasifica- tion (In Polish) Rauk, J Koks Smolu Gaz V28, Nl1-12, Nov-Dec 1983, P249-253

The principles of hydraulic fracturing are discussed and the results of its application are presented: (1) in brown coal seams of the Moscow Basin, USSR, (2) in bituminous coal seams of Wisichansk and South Abinsk, USSR and (3) seams at depths of 840-1250m in the Campine Coalfield, Belgium.

843131 Method of determining the outburst susceptibility of coals (In Russian) Savchenko, V V Khim Tverd Topl N3, May-June 1983, t>87-89

Treatment of coal with potassium iodide causes samples of outburst-prone coals to be reduced to a greater extent than non- hazardous coals. This is used as the basis of a method of asses- sing the propensity to outburst of coal seams.

843132 Acoustic emission/rock pressure measuring system (In Japanese) Sakiyama, Z Nippon Kogyo Kasld V98, Nl136, 1982, P1020-1022

A system has recently been developed in Japan which auto- matically and continuously monitors changes in acoustic emis- sion (AE) and rock pressure and checks the relation between these parameters. Electrically transmitted data from AE sensors and hydraulic pressure capsules embedded in the roofs of deep roadways are analysed and movement predicted on the basis of AE count, frequency distribution of maximum amplitudes and the stress strain relationship.

843133 Computer optimization and evaluation of cut-und-fill method (In Chinese) Jian, P Nonferrous Met V35. N4, Nov 1983, PI-6

A computer program has been compiled on the basis of 'deci- sion theory' to optimize filling systems and evaluate stoping methods in underground mines. In the program finite element analysis is used for verification of stope size and stepwise regres- sion is used for the statistical description of technological results.

843134 Effectiveness of working coal in a tectonically disturbed thin seam, taking as an example the ancient Karol Mine (In Pol,sh) Drewniak, R; Malek, J Przegl Gorn V39, NIO, Oct 1983, P392-398

Testing for the effectiveness of working tectonically disturbed coal is described and a brief description of geological conditions at the Karol Mine, Poland is given. An account of the working of seam 620 is included.

843135 Sub-level caving in steep seams (In French) Poyol, F Publ Tech Charbon Fr N3, 1983, P153-166

A brief account is given of the anthracite deposits at La Mure, France, and the geological factors which affect their mining: ir- regular seams, carbon dioxide outbursts, fire and water inflows. The mining methods in use are described including remotely controlled loaders and the "storage room' and the dynamics of sub-level caving are briefly examined.

95A

843136 Prevention of instantaneous outbursts of coal and gas Hargraves, A J Queensland Govt Min J V84, N984, Oct 1983, P391-399

Measures employed in prevention or partial prevention of in- stantaneous outbursts are reviewed in the light of experience gained in Australia and other countries. These include: protec- tive seam working, seam destressing and avoidance of work in highly stressed areas, seam gas predrainage, water infusion and reduction in rates of face advance.

843137 Increasing safety of mining coal seams prone to rock bursts (In Russian) Dukukin, A V Ugol Ni l , Nov 1982, P31-34

Methods for rock burst forecasting and control used in under- ground mines in the USSR are reviewed. Forecasting methods are based on seismic and geologic surveying and the instruments in current use are briefly described. Preventive methods include seam degassing through long boreholes, injection of water and surfactants, stress relaxation by large diameter drilling, use of hydraulic stowing instead of caving in deep mines, and use of remote control in hazardous seams.

843138 Adsorbed moisture as a complex indicator of the gas-dynamic state of a coal seam (In Russian) Pestryakov, B V Ugol Ukr N12, Dec 1982, P36

The factors which influence the efficiency of water infusion into coal seams for outburst prevention are considered. Absorbed moisture reduces the methane content in coal seams and the ab- ility of the coal to accumulate potential elastic energy. Nuclear Magnetic Resonance (NMR) can be used to measure the mois- ture adsorption and the application of NMR for optimising water infusion into coal seams is discussed.

843139 Condition of the solid coal surrounding outburst cavities in steep seams (In Russian) Khorunzhii, Y T Ugol Ukr N12, Dec 1982, P37-38

The rock burst hazards in zones close to cavities left after rock bursts were assessed. The extent of the destressed zone was determined from the velocity of methane emitted from a test borehole in the coal face and the compressive and dynamic strength indices of the coal were also obtained. Results showed that the zones close to the cavities were particularly hazardous and in steep seam conditions, the zone about 1.5m from the base of the cavity was most at risk from another outburst.

843140 Hydraulic mining of slightly inclined seams in difficult mining and geological conditions (In Russian) Radko, B V Ugol Ukr N2, Feb 1983, P8-9

The use of hydraulic mining in an inclined, 1.3m thick seam where the roof is difficult to break down and the floor is prone to heave, is evaluated. Hydraulic monitors with a water pressure of 9-10MPa were used for shortwall mining with a digital extra- ction pattern.