Failure and creep around an underground opening

Failure and creep around an underground opening

72A 942089 Direct observation of microcracking and subsequent failure in quartz-feldspar rock (bisphere) under uniaxial commpression Jeong, G C; Ichik...

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72A 942089 Direct observation of microcracking and subsequent failure in quartz-feldspar rock (bisphere) under uniaxial commpression Jeong, G C; Ichikawa, Y; Kawamoto, T Proc International Symposium on Assessment and Prevention of Failure Phenomena in Rock Engineering, Istanbul, 5-7 April 1993 P335-341. Publ Rotterdam." A A Balkema, 1993 Mechanical properties of granitic rocks are strongly dependent on their complex microcrack systems. An experimental apparatus has been developed which allows direct observation of microcracking under a gradually increasing stress field. The primary stress-induced microcrack (the cleavage microcrack) initiates from healed pre-existing microcracks in feldspar grains at about 30MPa. With increasing stress, further cracks initiate and propagate from healed pre-existing grain boundary microcracks between quartz and feldspar grains. Strain localization and damage in crystalline rocks can be studied. 942090 Index properties and acoustic emission in some Chilean rocks Acevedo, P M; Medrano, S A Proc International Symposium on Assessment and Prevention of Failure Phenomena in Rock Engineering, lstanbul, 5-7 April 1993 P351-355. Publ Rotterdam: A A Balkema, 1993 Core samples from rocks experiencing rockburst problems in Chilean mines have been examined the laboratory. Acoustic emission has been monitored during Brazilian tests. A classification is proposed on the basis of count number related to failure load. The characteristic curve of count number vs failure load was also examined as a possible tool for assessing in situ stress by field monitoring in the mines.

942093 Materials failure relation of accelerating creep as empirical description of damage accumulation Cornelius, R R; Scott, P A Rock Mech Rock Engng V26, N3, July-Sept 1993, P233-252 A general failure relation in which rates of deformation are related to changes in deformation rate during tertiary creep was proposed by Voight in 1988. Both failure by stress corrosion and power law lattice deformation are examined as phenomenologically related to this materials failure relation. Quantitative predictive values are illustrated using examples from Mount Toc, Italy, and Mount St Helens, USA, and laboratory data from chevron notch short rod siltstone specimens.

942094 Slow movement investigations in clay slopes Bertini, T; Cugusi, F; D'Elia, B; Lanzo, G; Rossi-Doria, M Proc 6th International Symposhun on Landslides, Christchurch, 10-14 February 1992 V1, P329-334. Publ Rotterdam: A A Balkema, 1992 Geomorphological and geotechnical aspects of movements on a slope of 8-13 deg in the Adriatic foothills of the Appenines are discussed. Up to 30m of silty-clay detrital cover lies over bedrock of stiff stratified marly clays. The geometry of the slope conforms to an infinite slope, but measured piezometric levels were not consistent with parallel-to-slope flow conditions. Seepage modelling was undertaken. It is concluded that the ground movement is governed by maximum seepage forces within the cover and in the superficial softened portion of the bedrock.

Time dependent behaviour 942091 Downslope movements at shallow depths related to cyclic pore-pressure changes Eigenbrod, K D Can Geotech J 1/30, N3, June 1993, P464-475 Slow shallow movements on a gentle slope near Yellowknife caused excessive tilting of timber piles, which were replaced by rigid concrete piers capable of resisting the forces of the moving soil. Stability analysis indicated the slope was not in a state of limit equilibrium. An extensive monitoring system was installed and the slope clay characterised in the laboratory. Results suggest the creep is caused by cyclic pore pressure changes in the clay. Soil movement is greatest at the surface, decreasing almost linearly with depth to zero at about 2m. There is no apparent slip surface. 942092 Classification of crystalline drill cores from the KTB deep well based on strain, velocity and fracture measurements Zang, A; Berkhemer, H Int J Rock Mech Min Sci V30, N4, Aug 1993, P331-342 Anelastic strain recovery, ultrasonic wave velocity, and Brazilian tensile strength were measured on cores from the KTB pilot bore. Changes in physical properties as a result of stress relief microcracking were investigated. Principal recovery strains decreased exponentially with increasing depth, irrespective of lithology. Crack-induced and textural anisotropy were evaluated from pressure-dependent wave velocity data and strength anisotropy from Brazilian test data. Gneissic samples undergo dilatant stress relief microcracking whilst lamprophyre and metabasites are characterised by a predominantly viscoelastic component of recovery strain.

942095 Failure and creep around an underground opening Cristescu, N D Proc International Symposium on Assessment and Prevention of Failure Phenomena in Rock Engineering, lstanbal, 5-7 April 1993 P205-210. Publ Rotterdam: A A Balkema, 1993 The dependence of damage and failure of rocks on loading history is first illustrated. Time dependent damage and creep failure are further examined using an energy of microcracking criterion and a nonassociative elastic-viscoplastic constitutive law. A creep failure in laboratory tests and failure and creep around underground openings, and their prevention, are analysed.

942096 Testing and modeling of backfill used in salt and potash mines Van Sambeek, L L Proc International Symposium on Rock Support, Sudbury, 1619 June, 1992 P583-589. Publ Rotterdam: A d Balkema, 1992 Use of salt tailings backfill can improve ground control and reduce environmental waste disposal problems. Analysis of rock mechanical benefits requires numerical modelling. The approach used to characterise the behaviour of crushed salt backfill at the Waste Isolation Pilot Plant is outlined. Laboratory testing and development of constitutive models are described. Much of this information can be applied at other sites. The WlPP backfill model has been fitted to laboratory data for salt tailings and used in finite difference modelling of the behaviour of a potash mine.