Geosynthetic strength — ultimate and serviceability limit state design

98A 942296 Better grade of grade Miyake, T T; Lay, G; Peak, M T; Thielen, D L Civ Engng, N Y V63, NIO, Oct 1993, P52-55 A new technique, landform contour grading, combining geogrid reinforcement with state-of-the-art land planning and grading design, has been used to construct safe, economic, and aesthetic natural looking slopes in California. Initially planned 2:1 slopes with crib walls were rejected on grounds of appearance and flatter slopes were not economically viable considering land values. The solution was to use primary layers of HDPE geogrid reinforcement up to 12m long, secondary reinforcement of polymer geogrids, and a grid pinned to the surface to reduce erosion and encourage vegetation. 29 very large slopes at angles up to 45 deg were constructed.

942297 Large-scale triaxial compression testing of geocell-reinforced granular soils Bathurst, R J; Karpurapu, R Geotech Test J V16, N3, Sept 1993, P296-303 Triaxial tests on 200mm diameter specimens of sand and limestone aggregate, unreinforced or containing a single horizontal layer of geogrid, are reported. The reinforced specimens had height:diameter ratio of unity, typical of conditions in base courses. The stiffening effect and strength increase due to enhanced confinement effects are shown. Peak friction angle from the unreinforced specimens may also be applied to the composite specimen. A simple elastic membrane model can be used to estimate enhanced apparent cohesion of the reinforced specimens.

942298 Behaviour of fibre-reinforced cemented sand under static and cyclic loads Maher, M H; Ho, Y C Geotecb Test J V16, N3, Sept 1993, P330-338 Artificially cemented sand specimens containing randomly oriented glass fibres were subject to static and cyclic compression tests and splitting tension tests. Compressive and Brazilian strengths were significantly increased by the reinforcement, the improvements being greater at higher fibre contents and longer fibre lengths. Both friction angle and cohesion were increased. Addition of fibres contributed to increased brittleness index of cemented sands and increased total energy absorption capacity. The number of load cycles to failure and cyclic failure strain were also increased by fibre reinforcement.

942299 Hydraulic conductivity of geotextiles under typical operation conditions Ling, H I; Tatsuoka, F; Wu, J T H; Nishimura, J Geotext Geomem 1/12, N6, 1993, P509-542 Cohesive soils may potentially replace expensive granular backfill provided the excess pore pressures and deformations when subject to moisture change or loading can be controlled by drainage. Cross-plane and in-plane hydraulic properties of woven and nonwoven geotextiles have been measured under typical in-service conditions for virgin samples and samples retrieved from the field. An equation is derived to predict hydraulic conductivity of geotextiles which includes effects of confining stress and a factor to account for influence of longterm retention of fine particles.

9423OO Bearing capacity of geosyntbetic reinforced soil using variational method Dixit, R K; Mandal, J N Geotext Geomem VI2, N6, 1993, P543-566 The variational approach of Baker and Gerber (1977) is used to determine the bearing capacity of a geosynthetic-r¢inforced soil. The rupture surface and normal stress distribution which satisfy the conditions of limiting the conditions of limiting equilibrium are established, yielding the lowest possible value of applied load. Results are in good agreement with available experimental data.

942301 Determination of the optimal lower-bound bearing capacity of reinforced soil-retelning wall using finite elements and nonlinear programming Singh, D N; Basudhar, P K Geotext Geomem VI2, N7, 1993, P665-686 Lysmer's method as modified by Basudhar et al (1979, 1981), based on finite elements and a nonlinear programming technique, is applied in a generalized approach to obtain an optimal solution for lower bound beating capacity of a reinforced earth retaining wall. The analysis incorporates soil anisotropy as a result of reinforcement. The method is validated against published theoretical and experimental data.

942302 Model square fooling on geotextile reinforced clay foundation Mandal, J N; Sah, H S Trans lnst Eqrs Amt Civ F,mgng VCE35, N2, June 1993, P165-169 Model tests were carried out with 100mm square rigid footings symmetrically above 400ram square layers of nonwoven geotextile buried in the clay subgrade. The footing was forced into the clay at penetration rate of about lmm/minute until failure or 50mm settlement. Effects of the depth below soil surface of the geotextile on settlement behaviour and bearing capacity are evaluated. Improvements at nearly all levels of deformation and settlement reduction were found with use of geotextile.

942303 Geosynthetic strength - ultimate and serviceability limit state design Fannin, R J; Herman, S Proc Conference Stability and Performance of Slopes and Embankments I!, Berkeley, 29 June-I July 1992 V2, P14111426. Publ New York: ASCE, 1992 (ASCE Special Geotechnical Publication No 31) An instrumented sloped geogrid-reinforced soil wall, constructed in 1987, has been monitored over a 4 year period. Creep characteristics of the geogrid have been calculated using the indpendent measurements of force and strain on the grids. These results are compared to laboratory load-strain-time data from rapid loading creep tests, with a view to establishing correlations to enable extrapolation of laboratory accelerated test data to ultimate and serviceability limit state design.