Roof bolting in underground mining: a state-of-the-art review

157A Drag cutting experiments were carried out on hard abrasive rocks in order to develop a method of preweakening the rock ahead of the kerf cutters, thereby allowing reduction of cutting loads and high wear rates. The 'prewcakening' methods used were indenting and single and double slotting. The best cutter force reduction achieved with the indentor was 70%; with double slotting a reduction of 99% was achieved. Design for preweakening systems to be fitted to the basic kerf cutterhead were developed. Avail: The Bureau, 4800 Forbes Ave, Pittsburgh, Pa, 15213

USA H a r d n e s s , a b r a s i o n and w e a r See: 844323

Rock and Soil Improvement Techniques See also: 844189, 844306 844324 Pump packing - the safe way to pack Colliery Guard V232, N2, Feb 1984, P58-64 A review of current pump packing systems and materials. 844325 In-plane hydraulic properties of gentextiles Koerner, R M; Bove, J A Geotech Test J V6, N4, Dec 1983, P190-195 A test method was developed to measure the parallel flow of water in a constant head device using geotextile specimens of 61.0cm by 30.6cm. Transmissivity (the in-plane coefficient of permeability times the geotextile thickness) was measured for a range of needled nonwoven textiles and large geotextile specimens. With multiple layers of fabrics, transmissivity was seen to increase in proportion to the thickness of the total number of layers. 844326 VIII ECSMFE - Helsinki Nutt, J L Ground Engng V17, N2, March 1984, P7-11 Report of an informal discussion of the British Geotechnical Society, held on 8 June 1983. Three speakers reported on the 8th European Conference of Soil Mechanics and Foundation Engineering. The theme of the conference was ground improvement and the speakers reported on aspects of most interest to them: stone columns, dynamic consolidation and vacuum preloading. 844327 Gootextiles as filters Hoare, D J Ground Engng V17, N2, March 1984, P29-44 A review of fabric filters. The advantages and disadvantages of fabric filters over granular filters are discussed. The mechanism of filtration is examined. Determination of fabric properties relevant to filtration are discussed. Design approaches for fabric filters are reviewed.

Bolts and anchors 844328 Foundations in tension - ground acbors Hanna, T H Clausthal, Germany: Trans Tech Publications, 1982, 573P 844329 Strata reinforcement - history, techniques and material development Lorentzen, A J; Moore, R K Colliery Guard V232, N2, Feb 1984, P45-53 84433O Roof bolting in underground mining: a state-of-the-art review Peng, S S; Tang, D H Y Int J Min Engng V2, N1, March 1984, P1-42

Roof bolts can be divided into 2 major groups: the pointanchored (or tensioned) bolt and the full-length-anchored (or nontensioned) bolt. From the review it is concluded that for mechanical bolting 2 parameters in particular need more study: the optimum design of the shape and type of expansion shell and the optimum bolt tension for a specific bolt pattern. For the fully grouted resin bolt, the most critical requirement is to develop a fast-setting, low-cost, nontoxic grouting material. Geological conditions play an important role in the successful application of any roof bolting system. Careful installation and continuous monitoring are also essential. 75 refs. 844331 Study of the behavioor of vertical rock anchors using the finite element method Yap, L P; Rodger, A A lat J Rock Mech Min Sci V21, N2, April 1984, P47-61 To provide a more fundamental approach to rock anchor design a simple isoparametric finite element program has been developed. The stress-strain pattern in the fixed anchor zone has been obtained for a rock/grout ratio of 1:2 and the results obtained are compared with those derived experimentally. The results show the most severe position of shearing to be at the rock/grout interface and that partial debonding is not a serious problem. 65 refs. 844332 Experimental study of beam building mechanisms using fully grouted belts in bedded mine rocks Snyder, V W; Krohn, R L In: Strata MeclmMcs (paper to the Sympmimn om Strata Met&talcs, Newcastle upon Tyne, 5-7 April 1982) P234-236. Publ Amsterdam: Elsevier, 1982 A study was carded out tO assess the beam building mechanism using fully grouted bolts in soft rock. A comparison of the effectiveness of mechanical and fully grouted bolts in reducing maximum deflection was made using small plaster board beam models. Results indicate that beam building occurs to a higher degree of reinforcement with fully grouted bolts than with mechanical bolts. 844333 Elasticity soinfion for the shear stiffness of ~ fall-grouted resin roofeolt Snyder, V W; Schwab, P M; Gerdeen, J C In: Strata M o c h a , s (paper to the S y m p o m on Strata Meckanles, Newcastle uptm Tyme, 5-7 April 1982) 1'237-240. Publ Amsterdam: Elsevier, 1982 The bolt is modelled as a beam on an elastic foundation where the theory of elasticity is used to determine the foundation modulus of the resin-rock combination. The results obtained are compared with those from a three-dimensional finite