Li, J & Taylor, DA 1993, Sourcebook on fatigue crack propagation: thresholds and crack closure, 1, Engineering Materials Advisory Services Ltd., UK.
Indraratna, B 1993, 'Effect of bolts on failure modes near tunnel openings in soft rock', Géotechnique, vol. 43, no. 3, pp. 433-442.
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The Paper elucidates the potential failure modes around a circular tunnel opening subjected to a hydrostatic stress field. Physical models have been tested in the laboratory using a large cubical triaxial apparatus to investigate the effect of grouted bolts on failure mechanisms. Depending on the bolt density, the observed failure of a bolted tunnel can deviate significantly from the theoretical rupture surfaces (log spiral) anticipated for an unsupported circular opening. The influence of discontinuities on the rupture process near the tunnel wall is also explored. It is shown that by use of a high bolt density, the propagation of slip lines and the risk of failure close to the tunnel boundary can be minimized. The failure zone (delineating wedges) around the tunnel wall becomes smaller with increasing degree of reinforcement. L'article s'intéresse aux modes possibles de fractu-ration autour de l'ouverture circulaire d'un tunnel dans un champ de contraintes hydrostatique. Des modèles physiques ont été expérimentés en laboratoire, à l'aide d'un appareillage triaxial pour des échantillons cubiques de gros volume, afin d'étudier l'influence des boulons jointifs sur less mécanismes de fracturation. Selon la densité de boulons, la fracturation observée dans un tunnel boulonné peut s'éloigner significativement des surfaces de rupture théoriques (en spirale logarithmique) prévues pour une ouverture circulaire non soutenue. L'influence des discontinuités sur le mécanisme de rupture à proximité de la paroi du tunnel a également été étudiée. Il apparaît que, en utilisant une forte densité de boulons, l'on peut minimiser la propagation des lignes de glissement et le risque de fracturation à proximité des limites du tunnel. La zone de fracturation autour des parois du tunnel devient moins étendue si l'on augmente le degré de renforcement.
Indraratna, B & Balasubramaniam, AS 1993, 'Closure to “ Performance of Test Embankment Constructed to Failure on Soft Marine Clay ” by B. Indraratna, A. S. Balasubramaniam, and S. Balachandran (January, 1992, Vol. 118, No. 1)', Journal of Geotechnical Engineering, vol. 119, no. 8, pp. 1326-1329.
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Indraratna, B, Wijewardena, LSS & Balasubramaniam, AS 1993, 'Large-scale triaxial testing of grey wacke rockfill', Géotechnique, vol. 43, no. 1, pp. 37-51.
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This Paper describes the results of a series of large-scale triaxial tests conducted on greywacke rockfill, used in dam construction in Southern Thailand. The tests are conducted at low to moderate confining stresses to relate their findings to the stability of rockfill dams. Considering the current test results in conjunction with previous laboratory data, revised failure criteria for rockfill are proposed in non-dimensional form. For both low and high confining stresses, lower and upper bounds of strength envelopes have been established, based on a wide array of granular materials. The influence of the confining stress on the shear strength of rockfill is studied in depth, and the implications of a non-linear envelope at low normal stress levels on the stability of rockfill dams are discussed. Although two parallel rockfill gradations for specimens compacted to similar porosities are considered, the exact role of particle size effect on shear strength is not examined in detail, as the difference in maximum particle sizes tested in this study is not sufficiently large. Cet article décrit les résultats d'une suite d'essais au triaxial à grande échelle réalisés sur du remblai rocheux (greywacke) utilisé pour la construction de barrages dans le sud de la Thaïlande. Ces essais sont exécutés à des pressions de cellule faibles à modérées pour rapprocher les résultats de la stabilité de barrages à enrochement. En considérant les résultats existant d'essais, en conjonction avec les données de laboratoire précédentes, des critères de rupture de l'enrochement sont proposés dans une forme sans dimensions. Pour des pressions de cellule faibles et élevées, les enveloppes basses et hautes de résistance ont été établies, basées sur un vaste ensemble de matériaux granuleux. L'influence de la pression de cellule sur la résistance au cisaillement est étudiée en profondeur et les conséquences d'une enveloppe de rupture non linéaire à containtes...
Sheng, D & Knutsson, S 1993, 'Sensitivity analysis of frost heave - a theoretical study', Frost in geotechnical engineering. Proc. 2nd symposium, Anchorage, 1993, pp. 3-16.
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A frost heave model based on quasi-steady state heat and water flow is presented. The model is verified against experimental results. The sensivity of computed frost heave is analyzed, which shows that, 1) the important factors affecting frost heave include overburden pressure, temperature gradient, unfrozen water content in frozen soil, and permeability of the soil; 2) increasing over-burden pressure prevents frost heave by elongating frozen fringe and increasing the space between lenses, and the effect of overburden pressure is not significant for clays; 3) decreasing temperature gradient prevents frost heave by increasing the thickness of frozen fringe and reducing ice lens thickness; 4) as the unfrozen water content increases, the computed heave first increases rapidly and then approaches a constant value at moderate and high unfrozen water content. -from Authors
Sheng, D, Axelsson, KB & Knutsson, S 1993, 'Finite element analysis for convective heat diffusion with phase change', Computer Methods in Applied Mechanics and Engineering, vol. 104, no. 1, pp. 19-30.
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