extrusion loads can be controlled by varying the configuration of the die bore, and that theoretical analysis predicts extrusion loads of the different die bore configurations. An appendix by K.G.Hoge, entitled "Dynamic tests on rock bolts", is included. 1770 MCWILLIAM~, PC GOOCH, AE Ground support systems in block cave mining. A survey. Report .25F. US BUR .MINES, IC 8679,1975,46P. Ground support problems in four major block-cave mines were investigated to assess the state-of-the-art and to delineate areas for future research. 1771 VAN DUYSE, H Supporting the roadway-In French and Flemish. ANN.MINES BELG. NI2, DEC .1974,P1217-1249. This paper was presented at an EEC symposium in November 1973 and reviews progress at that time in the support of mine roadways, including the use of enhydrite or concrete lagging, gunitIn~, spraying concrete, bolting and reinforced concrete panels. The total time per metre of roadway required for the setting of different types of support is compared. Where geological conditions are favourable, strata bolting as practised in Lorraine is the quickest and cheapest method; such conditons are, however, rare. For roads subject to heavy rock pressures circular supports consisting of concrete arches or prefabricated concrete elements are most effective.
Geological factors of importance in underground excavations See also abstract: 1863 .
1775 KRAVTSOV, AI Geological factors in outbursts of coal, gas and rock. In Russian. UGOL,VS0, NT, JULY, 1975, P21-23.
Construction methods 1776 DVORAK,A Tunnelling of the Underground below the existi~ tummels. Comfaremce. 4F,2R. PROC .THIRD CON~qESS, INT.SOC .ROCK MECH.D~VER,1974, V2, PART B, 1974,P1262-1266. 1777 SAGASETA, G UNIV. SANTANDER, E ESCARIO,V LAB. ~%KNSP .MECH .SUELD,MAI~ID, E Influence of construction procedures on ground pressures around a tunnel. Conference.10F,6R. PROC .THIRD CONGRESS, INT. SOC .ROCK MECH.DE~VER, 1974, V2,PART B,1974,P1318-1325. A finite elelmmt model is presented which tekes into account the construction method where considering the distribution of ground pressures around a tunnel. The model is used to analyse a tunnel in which field measurements are carried out.
1778 LLOVGRA, LO BECEDONIZ, JF Excavating works for the enlargement of Villarino power plant .Confer ence. 2F, 7R. PROC .THIRD CONGRESS, INT.SOC .ROCK MECH.D~VV~q, 1974, V2,PART B,1974,PI365-1370. The excavation works at Villsrino are discussed, considering especial~v the problems associated with maintaining the power sets under safe operating conditions, particularly the determination of the admissable vibration levels and the control of the blasting.
1772 DESAI, CS ARMY WAT~W. EXPT. STAT. VICKSBURG, MISS, USA JOHNSON, LD ARMY WAT~W. EXPT. STAT.VICKSBURG, MISS, USA Influence of bedding planes on sterility of boreholes. Conferm~ce. 6F, IT, SR. 1779 PROC.THIRD CONGRESS, INT.SOC.ROCK MECH.DENVER 1974,V2, COMES, G ELECTR. DE FRANCE, PARIS, F PART B, 1974,P997-I002. The pressure headwater tunnel driving by a tunnelA finite element procedure is used far stability analysis ling machine for a hydroelectric power plant. A of deep boreholes in geologic media traversed by cleavage geotechnical analysis of the problem. Conference. In or bedding planes at different inclinations. A relation French.hF, ST, 8R. between bedding plane angles and failure loads is obtained PROC.THIRD CONGRESS, INT.SOC.ROCK MECH.DE~Cg~,I974, from a series of finite element solutions. The extents of plastic zones at failure based on Mohr-Coulomb criterion V2'PART B,1974,P1476-1480. are also compared. 1780 FOURMAINTRAUX, D 1773 COLOMBKT,G DFJEAN, M ECoLE MINES, NANCY, F GESTA, P DUBART, JC ECOLE MINES, NANCY, F Classification methods of discontinuities in rocks JOSIah, JP ECOLE MINES, NANCY, F and rock masses in order to determine their influStrata control around face working. Conference. In ence on performances of a pick boring machine.Con. French.8F, 7R. ference. In Fremch. 5F,IT,6R. PROC .THIRD CONGRESS, INT .SOC .ROCK MECH.D~VER,1974,V2, PROC .THIRD CONGRESS, INT. SOC .ROCK MECH.D~V~, 1974, PART B, 1974, Pl123-1129. V2,PART B, 1974,P1481-1486.
1774 FONT, JV Characteristics of Joint systems observed in the exploratory tur~el at Turo de la Rubira, Barcelona, Spain. Conference. In French. 3F, SR. PROC .THIRD CONGRESS, INT.SOC .ROCK MECH.D~IV~,1974, VZ, PART B,1974,PI272-1277. Orientation, spacing, persistance and surface characteristics of joints intersecting the rock mass at Turo de la Rublra were observed. From an s~alysis of observations on more than 2000 Joints, using equal-area projection diagrams, at least seven families of Joints were detected, but were often poorly defined.
1781 JAGER, B G~DL. LANDES .KREFELD;D REINKARDT, M GEOL. IANDES .KREFELD; D WEB,q, P GEOL.LANDES .EREFELD, D Rock properties and their influer~e on the use of tunnelling machines. Confer emc e. In Germem .6F,2T, 5R. PROC .THIRD CONGRESS, INT.SOC .ROCK MECH.D~IVER, 1974, V2, PART B,1974, P149~-1500.
1782 0LSON, JJ OI~ON, KS ARPA-Bureau of Mines rock mechanics and rapid exca-