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Determination of support reaction curve for steel-supported tunnels
REINFORCEMENTzEARTH Sayano-Shushenskoe hydrostation gravity arch dam. The platform was subsequently fastened to the foundation by means of advance grouting and prestressed anchors installed to a depth of more than 2Om. This article describes: prestressed anchor manufacture; drilling and preparation of anchor boreholes; transport of the anchors and their placement in the borehole; anchor grouting, standing and tensioning; and tension release and anchor cutting off. (J.M.McLaughlin)
Direct rock support methods 956225 Determination of support reaction curve for steel-supported tunnels M. Verman, B. Singh, J. L. Jethwa & M. N. Viladkar, Tunnelling & UndergroundSpace Technology, 10(2), 1995, pp 217-224. Based on the analysis of instrumentation data obtained from several tunnels in India, an empirical approach has been proposed for determination of the support reaction curve for tunnels supported with the steel rib-backfill support system. Expressions have been obtained for determining the stiffness of this support system with three types of backfills-concrete, tunnel muck, and gravel. These expressions show that the steel rib-backfill support system exhibits a non-linear behaviour under pressure, unlike the normally assumed linear elastic behaviour, due to the continuously changing back&ill stiffness. The backfill, though not the main load carrying element, significantly influences the bahaviour of the support system under pressure. The behaviour of three types of backfills-concrete, gravel, and tunnel muck-under pressure, has been studied. The concrete backfill provides a stiffer support than the other two types of backfills and is, therefore, preferable for the elastic ground condition. The tunnel-muck and the gravel backfills may be more suited to the moderately squeezing and the highly squeezing ground conditions, respectively, as the latter is relatively more flexible. (Authors)
Grouting
In this study, soil/geotextile interaction is characterized by the following general equation - 8 = 0, + tan P(cr,,,)” - where 0 anda nor are shear and normal stresses on the failure plane at failure, 8, is the soil/fabric adhesion component, and S+ and n are friction indexes. This equation provides a general relationship in which the classical Mohr-Coulomb law is considered as a special case. It holds for a wide range of normal stresses and describes soil/geotextile interaction in terms of material-related parameters. A theoretical interpretation of the effects of critical factors affecting soil/geotextile interaction is based on this equation. The four main factors examined are soil/geotextile adhesion, normal stress, deformation of junctions at the soil/fabric interface, and surface roughness. (from Authors) 956228 Pull-out experiments with cohesionless and cohesive soils for reinforcement application A. K. Karmokar, H. Kabeya & Y. Tanaka, Sen-i Gakkaishi, 50(12), 1994, pp 608-614. To simplify the complex surface asperities of geotextile materials, different acrylic plates with embossed concavities on their surface were used as model reinforcing elements. Experiments on pull-out frictional behavior of such acrylic plates with both cohesionless and cohesive soils were carried out in the laboratory. The various trends of apparent pull-out frictional resistance are discussed. The roughness (concavity size) and soil particle diameter are found to play important roles in determining the pull-out frictional behavior. (from Authors) 956229 Predicted behavior of two centrifugal model soil walls Set Keung Ho & R. K. Rowe, Journal of Geotechnical Engineering - ASCII, 120(10), 1994, pp 1845-1873. The finite element method is used to predict the behavior of two centrifugal reinforced soil wall models, one reinforced with a geogrid, the other with a nonwoven geotextile. In the geotextile-reinforced model the effect of the intermediate layers that form part of the wrap-back facing is significant. In the geogrid-reinforced model, it is found that the interface shear strength between the till and the reinforcement is an important factor. (from Authors)
956226 Investigation of syneresis in silicate-aluminate groats S;,4i;fferis & A. S. Bahai, Geotechnique, 45(l), 1995, pp
956230 Use of geosyntbeties in infrastnwtore remediation R. M. Koerner & T.-Y. Soong, Journal of Infrastructure Systems - ASCE, l(l), 1995, pp 66-75.
The contraction of silicate-aluminate grout solution is studied from the moment of mixing, and the influence of temperature and mix composition on syneresis of the set grout are investigated. Syneresis is quantified and the final values are estimated. Some of the mechanics of syneresis are elucidated. It is shown that syneresis must be a mainly chemical contraction process. Gravity was found to have a minor effect. It is shown that the only identified forces that work against syneresis are surface adhesion forces or mechanical interlocking. Syneresis was found not to occur if sufftcient bonding exists at the gel-matrix interface. It is shown that syneresis will occur in rock fissures with a rough sand-like texture or grouted sand masses only at very extended times, if at all. (from Authors)
This paper presents the manner in which geosynthetics might be considered for various aspects of infrastructure remediation based upon the primary function that is being served. Once decided, some of the many applications involving geosynthetics in infrastructure remediation are presented. (Authors)
Reinforced earth 956227 Theory of soillgeotextile interaction Y. E. El Mogahxy, Y. Gowayed & D. Elton, Research Journal, 64(12), 1994, pp 744-755.
Textile
956231 Statistical sample size for construction of soil liners C. H. Benson, Huaming Zhai 8c S. M. Rashad, Journal of Geotechnical Engineering - ASCE, 120(10), 1994, pp 17041724. A method is described for selecting the number of samples to be collected and tested during construction quality control of compacted soil liners. Charts are provided to select the sample size. The sample size depends on the properties on the soil, their spatial variability, and the number of lifts in the liner. (from Authors) 956232 Coir geotextile in civil engineering J. N. Mandal, Asian Textile Journal, 2(12), 1994, pp 38-46.
Direct rock support methods 956225 Determination of support reaction curve for steel-supported tunnels M. Verman, B. Singh, J. L. Jethwa & M. N. Viladkar, Tunnelling & UndergroundSpace Technology, 10(2), 1995, pp 217-224. Based on the analysis of instrumentation data obtained from several tunnels in India, an empirical approach has been proposed for determination of the support reaction curve for tunnels supported with the steel rib-backfill support system. Expressions have been obtained for determining the stiffness of this support system with three types of backfills-concrete, tunnel muck, and gravel. These expressions show that the steel rib-backfill support system exhibits a non-linear behaviour under pressure, unlike the normally assumed linear elastic behaviour, due to the continuously changing back&ill stiffness. The backfill, though not the main load carrying element, significantly influences the bahaviour of the support system under pressure. The behaviour of three types of backfills-concrete, gravel, and tunnel muck-under pressure, has been studied. The concrete backfill provides a stiffer support than the other two types of backfills and is, therefore, preferable for the elastic ground condition. The tunnel-muck and the gravel backfills may be more suited to the moderately squeezing and the highly squeezing ground conditions, respectively, as the latter is relatively more flexible. (Authors)
Grouting
In this study, soil/geotextile interaction is characterized by the following general equation - 8 = 0, + tan P(cr,,,)” - where 0 anda nor are shear and normal stresses on the failure plane at failure, 8, is the soil/fabric adhesion component, and S+ and n are friction indexes. This equation provides a general relationship in which the classical Mohr-Coulomb law is considered as a special case. It holds for a wide range of normal stresses and describes soil/geotextile interaction in terms of material-related parameters. A theoretical interpretation of the effects of critical factors affecting soil/geotextile interaction is based on this equation. The four main factors examined are soil/geotextile adhesion, normal stress, deformation of junctions at the soil/fabric interface, and surface roughness. (from Authors) 956228 Pull-out experiments with cohesionless and cohesive soils for reinforcement application A. K. Karmokar, H. Kabeya & Y. Tanaka, Sen-i Gakkaishi, 50(12), 1994, pp 608-614. To simplify the complex surface asperities of geotextile materials, different acrylic plates with embossed concavities on their surface were used as model reinforcing elements. Experiments on pull-out frictional behavior of such acrylic plates with both cohesionless and cohesive soils were carried out in the laboratory. The various trends of apparent pull-out frictional resistance are discussed. The roughness (concavity size) and soil particle diameter are found to play important roles in determining the pull-out frictional behavior. (from Authors) 956229 Predicted behavior of two centrifugal model soil walls Set Keung Ho & R. K. Rowe, Journal of Geotechnical Engineering - ASCII, 120(10), 1994, pp 1845-1873. The finite element method is used to predict the behavior of two centrifugal reinforced soil wall models, one reinforced with a geogrid, the other with a nonwoven geotextile. In the geotextile-reinforced model the effect of the intermediate layers that form part of the wrap-back facing is significant. In the geogrid-reinforced model, it is found that the interface shear strength between the till and the reinforcement is an important factor. (from Authors)
956226 Investigation of syneresis in silicate-aluminate groats S;,4i;fferis & A. S. Bahai, Geotechnique, 45(l), 1995, pp
956230 Use of geosyntbeties in infrastnwtore remediation R. M. Koerner & T.-Y. Soong, Journal of Infrastructure Systems - ASCE, l(l), 1995, pp 66-75.
The contraction of silicate-aluminate grout solution is studied from the moment of mixing, and the influence of temperature and mix composition on syneresis of the set grout are investigated. Syneresis is quantified and the final values are estimated. Some of the mechanics of syneresis are elucidated. It is shown that syneresis must be a mainly chemical contraction process. Gravity was found to have a minor effect. It is shown that the only identified forces that work against syneresis are surface adhesion forces or mechanical interlocking. Syneresis was found not to occur if sufftcient bonding exists at the gel-matrix interface. It is shown that syneresis will occur in rock fissures with a rough sand-like texture or grouted sand masses only at very extended times, if at all. (from Authors)
This paper presents the manner in which geosynthetics might be considered for various aspects of infrastructure remediation based upon the primary function that is being served. Once decided, some of the many applications involving geosynthetics in infrastructure remediation are presented. (Authors)
Reinforced earth 956227 Theory of soillgeotextile interaction Y. E. El Mogahxy, Y. Gowayed & D. Elton, Research Journal, 64(12), 1994, pp 744-755.
Textile
956231 Statistical sample size for construction of soil liners C. H. Benson, Huaming Zhai 8c S. M. Rashad, Journal of Geotechnical Engineering - ASCE, 120(10), 1994, pp 17041724. A method is described for selecting the number of samples to be collected and tested during construction quality control of compacted soil liners. Charts are provided to select the sample size. The sample size depends on the properties on the soil, their spatial variability, and the number of lifts in the liner. (from Authors) 956232 Coir geotextile in civil engineering J. N. Mandal, Asian Textile Journal, 2(12), 1994, pp 38-46.