Centrifuge model of an embankment failure. Technical note

7~A 872236 Axial beha~our and capacity of driven piles in calcareous sands Lu, B T D Proc 18th Offshore Technology Conference, Houston, 5-8 3,lay 1986 I'I. P579-588. P,tbl Richardson. Texas: OTC, 1986 Laboratory tests were carried out on a fully instrumented pile in calcareous sands prepared at varying densities and cement contents, in a large test drum where lateral and vertical confining stress could be varied. End bearing, skin friction and lateral stress on the pile were measured. The sand samples were characterised by cone penetration tests (CPT). Results indicate the behaviour of driven piles in calcareous sands is complex, but follows definite patterns. Most common design methods for piles in calcareous soils are doubtful. Load capacity of driven piles in calcareous soils is closely related to CPT data. 872237 Shaft frictional resistance of long pipe piles driven into dense sands Tsien, S I Proc 18th Offshore Technology Conference, Houston, 5-8 May 1986 VI, P601-608. Publ Richardson, Texas: OTC, 1986 Pile foundation problems in offshore siliceous sands are studied by analysing results from loading tests in coastal and offshore deposits in China. The mechanism and key factors influencing shaft frictional capacity are identified, and the effects of the structure and relative density of the sand, pilesoil load transfer characteristics, soil plugging of open ended piles, and the method of driving and loading are examined. Suggestions are made for further work.

Dams and embankments See also: 872028 872238 Embankment draining by the drainage spurs method. Evaluation of the efficiency of the method through three dimensional simulation and assessment of the gained stability (In French) Aigle, P; Desnouvaux, F; Prost, J P Rev Fr Geotech N36, 1986, P31-46 Steady groundwater flow induced by a series of parallel drainage spurs, of given depth and spacing and coupled with a drainage ditch, is examined for various embankment slopes and various distances to the recharge surface. An original analogue model is used to locate the water tables. Detailed quantitative study has been carried out over the vertical plane of symmetry of two spurs. The development of the water table curve, relative to the geometry of the spurs, has been studied. Drainage efficiency is examined from both hydraulic (drawdown) and mechanical (embankment stability) aspects, and design charts are presented. 872239 Hodograph transformation for flow through a dam with sloping walls and no tail water Boast, C W Water Resour Res I:22, NIO, Sept 1986. P1455-1461 An analytical method is proposed which will solve the unconfined saturated boundary value problem associated with an earth dam. It gives rate of flow of water through the dam, extent of surface seepage on the downstream side, and the shape and position of the water table within the dam.

872240 Centrifuge model of an embankment failure. Technical note Davies, M C R Proc Symposium on Failures in Earthworks, London, 6-7 ~larch 1985 P451-453. Publ London: Thomas Telford. 1985 Model tests examined the staged construction of granular embankments on soft clay foundations. Monitoring of pore pressures and deformation for an embankment which t:ailed shortly after construction showed zones of high shear strains propagating in the region of the eventual failure surface, resulting in progressive failure. Pore pressure measurements indicated the rise in total stress due to stress redistribution during progressive failure. 872241 Serviceability failure of a new railway embankment. Technical note Laird, C L Proc Symposium on Failures in Earthworks, London, 6-7 ~Warch 1985 P467-469. Publ London." Thomas Telford. 1985 Vertical drains were installed during the construction of a rockfill embankment on recent alluvium, to ensure stability during construction and enable specification limits on construction time and operational settlement to be met. Excess pore pressures dissipated relatively slowly, however, and, following consolidation analysis, berms were constructed to maintain embankment stability whilst a faster construction rate and surcharging were used. Even this was insufficient to meet contractual criteria, and finally it was necessary to remove most of the embankment and replace it with one on a piled foundation. 872242 Validating predictions of tailing embankment behavior with the centrifuge Rechard, R P; Sutherland, H J Proc 5th Engineering Mechanics Dirision Speciality Conference, Wyoming, 1-3 Aug 1984 V2, Pt316-1319. Publ New York: ASCE, 1984 Centrifuge tests were carried out to determine whether design principles developed for competent soil and rock materials could be applied to weak materials such as coal mine tailings. The first tests examined seepage. Steady state phreatic surfaces compared well with those from mathematical models, adding credence to both the centrifuge and mathematical models. The second test series compared predicted dam safety factors and failure surfaces with results from centrifuge tests. The traditional slip circle stability analysis indexed the safety of the dams, but did not accurately predict embankment behaviour. 872243 Centrifuge modeling of earth dam overtopping Dunn, R J; Simantob, E; Ko, H Y Proc 5th Engineering Mechanics Dirision Speciality _Conference, Wyoming, 1-3 Aug 1984 V2, P1320-1323. Publ New York." ASCE. 1984 The feasibility of centrifuge modelling of the overtopping of earth dams was examined with a series of scale model tests on rock and clay embankments. It was found that the method is suitable, and that erosion can be recorded using commercial quality photographic equipment. An equation for overtopping flow was developed, which will be validated when results from prototype or full scale tests are available. Further tests are planned to measure erosion rates.

~i: 1986 Pergamon Journals Ltd. Reproduction not permitted