High pressure jet-drilling experiments in some hard rocks

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in preformed holes, or by l:a~-is Of impermeable materials in slurry tremches, add freeziug. A :n~ of case s t ~ e s are Sl~mmsrlsed. 51 refs.

Influence of dynamic loads due to explosions or earthquakes 773154 SEISMIC TESTI~ OF ~EINFORCED EARTH WALLS Richardson, G N; Feger,, D; Fong, A J Geotech Emgmg Div~ ASCE, V103, NGTI, 1977, Pl-17 A 6m high reinforced earth test wall was subjected to low strain level forced vibration teats using mechanical vibrators amd high strain level explosive tests. Four existing reinf~ced earth walls were also subjected to fc~ced vibration tests. Criteria are presented for de1~cmining the ~ e s i ~ model frequencies of a reir~orced earth wall as a function of its effective height ar~ level of seismic excitation. Data are also presented showing the static d~c tie force distribution.

Comminution of Rocks 773155 RATIONAL TECHNOLOGY FOR THE~WAL ROCK ~REAKI~G Protas~, Y I S ~ Min Sci, VII, NS, Sept-Oct 1975, P505-507

drilling speed, specific power consumption, wear rate of the sintered carbide cutting edge, chip size distribution on the one hand add the bore_hole depth on the other hand-: The drillir~ system providing maximum efficiency is eval~ted. 773159 HIGH PRESSURE JET-DRILLI~D EXPERIMENTS IN SOME HARD ROCKS Pols, A C ASME paper 76-PET-50, 1976, 9P The test rocks used were Solnhofen llmestone~ Belgian limestone, Carrara ms~ble, Gres Bleu, quartzitic sandstone add Martelar~e schist. It was found that the rates of penetration are much lower in hard, impermeable rock than in permeable rock. Test results irzlicate that a laminated rock (Martelange schist) cannot be cut by Jets at a high rate, which calls for l ~ r i d bits. Isotropic rock can be Jet-drilled at higher than conventional drilling rates~ which may become profitable at daily rig costs in excess of about 20,000 dollars. Avail: ASME, 3~5 F~Tth S % New York~ NY, 10017, USA

Blasting 773160 INFLUENCE OF THE STRESS STRAIN S ~ E OF ROCK ON THE ENERGY CONSt~I~ON IN UNDERGROUND BOREHGLE ORE ~ E A K I ~ Rivkln, I D; Semer~ko, M I; Sakovich, V V Soy Min Sci, Vll, NS, Sept-Oct 1975, P533-

538 Thermal ar~ electrothermal rock breaking with comcemtrated and ddstributed action and respective technologies are compared. Taking account of the dependence of the energy construction of rock fracture on the temperature amd emergy loss, it is concluded that the most rational teahnology involves distributed action with a rock temperature not exceeding 300deg C.

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GUIDE FOR THE APPLICATION OF DRILLING AND BX~$TING METHGD OF LOOSENING FROZEN AND PERENNIALLY FROZEN GROUND AND MORAINES Natiomal Research Council, Canada, technical translation 1877, 1976, 27P Translated from the Russian~

Drilling 773157 HYE~AULIC ROCK DRILLS a~21'i'~ECONOMICS AND ENVIRONMENT Romell, V Int Constr, VlS, NS, Aug 1976, P61-67 This special feature on rock drilling methods add eqUil~nent is devoted to the development of imdividual r a ~ e s of h~Iraulic rock drilling equipmemt, with articles from U.S. amd European manufacturers;

Determination of the energy c o n ~ i o n of conversion Of the broken part of the ~ressc~l rocks to its l~m~tir~ state IX~dar the influence of the total field of static and dynamic stresses is considered; Blasting processes are amalymed for energy ~pemditure on elastic and plastic deformation or fracture; Results show that total or partial preliminsry relief of the static loads on the rock reduces the specific explosives consumption for breaking by a factor of 1.6-2.2.

773161 QUALZ~Y OF ROCK CRUSHING IN EXPLOSIVE ORE ~AKING Kuznetsov, V M; Faddeenkovj N N Soy Min Scij VII, NS, Sept-Oct 1975, P566-567 An empirical equation for calculating the variation of the specific explosive consumption with the yield of oversized material and the blasthole diameter is presented. To detarmine the yield of oversized material it is convenient to use the Weibull two-parameter distribution, which closely approximates the c r e a t i v e curve of grain size cc~position of the exploded rock in a wide ramge of c h a ~ of explosive hrecking psramet~rs. Empirical ~ calculated values are compared.

Cutting T ~ 1 5 8 INVESTIGATION OF THS POSSIBILITY OF SMALL. DIA~'f~a~ RO~A~Y ]~TT~.ING IN HARD ROCKS (IN

SmeAr) Tomek, M; ~ s k ~ , S Sb Ved Pr Vys Sk ~ar~ke Ostrave Rada stroJni, V21, NI~ i ~ , P189-212 Based on the results of tests, functional relationships have been derived between the

773162 C C Q ~ 0 ~ I O N OF ROCK FROPE~IES WITH THE PERFC~MANCE OF DISC CUF~ERS Phillips, H R; Biiginl N Proc Conference on Rock E~gir~erir~ (Newcastle-uporrTyne. ~-7 A I ~ I 1977 ),

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