Keywords: retaining walls, discrete element method, lateral earth pressure, limit equilibrium, reinforced soil.

Limit equilibrium has been used by many researchers to investigate the lateral earth pressure behind a retaining wall in active and passive conditions. In general, the number of static equilibruim equations is insufficient and the problem is solved by means of different assumption made for the relations between interslice forces. For example Shields and Tolunay [1] divided the soil mass into different slices and made assumptions for the direction of interslice forces in passive condition.

The Discrete Element Method (DEM) can be used for numerical analysis of different geotechnical problems such as retaining wall earth pressure distribution. The method (DEM) was presented the first in new concept, by C.S.Chang, for investigating bearing capacity of foundations [2], slope stability [3] and retaining wall [4].

In this model, the soil mass in the assumed failure surface behind the wall is considered as several discrete blocks connected with Winkler springs. One set of springs in the normal direction to simulate the normal stiffness and the other set is in the tangent direction to simulate the shear resistance at the interface. Behavior of the normal and tangent springs is elasto-plastic based on Mohr-Columb failure criteria. The solution of this method satisfies all equilibrium and compatibility conditions. The method has the simplicity of the classic limit analysis and offers more ability in solving problems in complex geometry and loading conditions such as seismic h/v impacts, pore water pressure, non-homogeneityof the soil, reinforced backfill soils and etc.

Chang [4] used the method to investigate the lateral active and passive earth pressure in static loading condition. By developing the method a computer program is established to determine the Pseudo-Static active and passive earth pressure. Also the program can investigate the effect of non-homogenity and reinforced backfill.

In this paper, the formulation of the method is briefly reviewed. Examples are shown to demonstrate the applicability of the method for analysis of earth pressure behind a retaining wall including dynamic lateral pressure of non-homogeneous soil. The results are compared with previous classic methods. Applicability of DEM for analysis of reinforced soil structure and advantages of this method over conventional methods are also discussed.

1

Shields, D.H. and Tolunay, A.Z., "Passive pressure by methods of slices", Journal of the Soil Mechanics and Foundation Division, ASCE, Vol. 99, No. SM12, pp 1043-1053, 1973.

2

Chang C.S., "Discrete Element Method for Bearing Capacity Analysis", Computers and Geotechnics, Vol. 12, pp 273-288, 1991. doi:10.1016/0266-352X(91)90026-C

3

Chang C.S., "Discrete Element Method for Slope Stability Analysis", Journal of Geotechnical Engineering, Vol. 118, No.12, pp 1889-1905, 1992. doi:10.1061/(ASCE)0733-9410(1992)118:12(1889)

4

Chang C.S., "Discrete Element Analysis For Active And Passive Pressure Distribution on Retaining Wall", Computers and Geotechnics, Vol. 16, pp 291-310, 1994. doi:10.1016/0266-352X(94)90012-4

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