Embankement for interchange constructed on soft ground applying new methods of soil improvement

38A soft soils is presented. Soil properties variability is analysed using the geostatistical kriging technique. The Monte Carlo method is then used to evaluate the distribution of safety factors against circular failure for blocks of finite length. The location and length of zones of highest risk of failure can be estimated. 891302 Improvement of soils by vertical rigid piles: application to construction of embankments on soft soils (In French) Combarieu, 0 Rev Fr Geotech N44, 1988, P57-79 The use of a network of vertical rigid piles to improve soft soil foundation embankments has been examined. Compaction by a single pile is first considered, then the effects of a network of piles, pile spacing, and surcharge loading. End bearing, capped, and piles of length less than soft soil depth are considered. A design example is illustrated, and a number of practical applications of pile reinforcements to embankment foundations are presented. 891303 Consideration of the interaction between dam and bedrock in a coupled mechanic-hydraulic Fig-program Erban, P J; GeU, K Rock Mech Rock Engng V21, N2. April-June 1988, P99-117 Discontinuities in a jointed rock mass largely determine the mechanical and hydraulic properties. A method, which accounts for the mechanic-hydraulic interaction in a 3-D finite element program, adopting the homogeneous model and assuming persistent discontinuities, is proposed. The influence of discontinuities on mechanical behaviour and permeability is analysed, the mechanic-hydraulic interaction illustrated using a simple model, and the finite element program outlined. The method is illustrated for a gravity dam. 891304 Embankment for interchange constructed on soft ground applying new methods of soil improvement Fukuoka, M; Goto, M Proc International Symposium on Prediction and Performance in Geotechnical Engineering, Calgary, 17-19 June 1987 P169176. Publ Rotterdam: A A Balkema, 1987 An embankment was constructed on soft ground where significant surface movement at the toe could not be tolerated. Two foundation stabilising methods were proposed: horizontal steel bars at the base of the structure to prevent lateral spreading, and foundation reinforcement with dry jet mixed (DJM) cement stabilised columns. Test embankments were constructed and results used to optimise modelling of the deformation. Finite element analysis was the most useful modelling method. Displacements around the final embankment were minimised. 891305 Gem State hydroelectric project Kuenzli, J R; Hedel, C W Proc 24th Syrup on Engineering Geology and Soils Engineering, Coeur D'Alene, 29 Feb-2 March 1988 P131-147. Publ Washington: Washington State University, 1988 Site investigation of the Gem HEP dam area, and implications for design are presented. Potential reservoir seepage was investigated using permeability measurements and results of closed form solutions and finite element methods. These show that measures against seepage are necessary, and a combined seepage blanket and drain trench was used. The design of the core

and filter is discussed. A non-plastic silt and gravel from onsite excavations were chosen. Construction methods, preparation of the rock foundation, treatment of the incised channel and manufacture of the gravel-silt core are described. 891306 Coupled mechauical-hydraulic hehaviour of earth dams with partial saturation Aubry, D; Chouvet, D; Ozanam, O; Person, J P Proc ECONMIG 86, Stuttgart, 16-18 September 1986 I/2, 13P. Publ Stuttgart." University of Stuttgart, 1986 Analysis of mechanical behaviour of an earth dam during construction, reservoir filling or drawdown must consider a three phase system, soil-water-air, with each phase exhibiting nonlinear mechanical and hydraulic behaviour. The complex and coupled equations of fluid flow in an unsaturated porous medium and the mechanics of the porous medium are first reviewed. A complete nonlinear iterative scheme is presented and implemented in the computer code GEFDYN. Attention is paid to initial and boundary conditions. 891307 Numerical simulation of incremental building of auisotropic earth embankment Bottero, A; Vidal, D Proc ECONMIG 86, Stuttgart, 16-18 September 1986 I,'2, 13P. Publ Stuttgart: University of Stuttgart, 1986 The staged construction of an embankment on compressible foundations has been simulated using finite element modelling. Cases of the embankment with higher, equal, or lower stiffness than the foundation are analysed. Effect of stiffness values on vertical and lateral movement of the embankment and stress distributions in the embankment and foundations are evaluated. 891308 Geotechnical aspects of the Carsington Dam failure Skempton, A W Proc 1lth International Conference on Soil Mechanics and Foundation Engineering, San Francisco, 12-16 August 1985 VS, P2581-2592. Publ Rotterdam: A A Balkema, 1988 The background to the failure, geology, and post failure investigation are first considered, including pore pressures, settlements and displacements prior to failure. The geotechnical properties of the yellow clay layer which formed part of the failure surface, and of the core material are examined. A stability analysis is presented and a failure mechanism proposed.

Slopes See also: 891085, 891136, 891172 891309 Hydrologic factors triggering n shallow hillslope failure Reid, M E; Nielsen, H P; Dreiss, S J Bull Assoc Engng Geol V25, N3, Aug 1988, P349-361 Rainfall and accompanying pore pressure rise were monitored using piezometers before and during a slump/debris flow in a hillside. This showed an area of anomalous decrease in soil hydraulic conductivity in a perched water table. A model of hillslope hydrology was used to analyse the data, indicating that only a slight decrease in hydraulic conductivity influences pore pressure, rates and directions of subsurface water flow, and location of failures in hillsiopes with layered, heterogeneous soils.

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