One-step analytical method for required reinforcement stiffness of vertical reinforced soil wall with given factor of safety on backfill soil

Abstract Background：The 2011 off the pacific coast of Tohoku earthquake (Mw=9.0) caused great damage of geotechnical structures in the vicinity of the eastern coasts. In contrast, many of reinforced soil walls constructed along the coast were less damaged by the tsunami. In this study, a model test using water tank is conducted to evaluate the behavior of a reinforced soil wall under strong water flow and water pressure like tsunami as an experimental prototype. The scale of model is 1/40, the height of wall is 25cm and the water level is 20cm, supposing that a tsunami hit the wall whose height is 10m in a full-scale without overflowing. Water flow hit the wall keeping its velocity and level. When the water penetrates into the backfill soil until ground water level is same as the level of water flow, the water was stopped and drained out of the tank.In this study, 2 test cases were conducted. One is a sound wall, and the other is a wall with some opening of the front panels which simulates the gap of the wall due to residual settlement after an earthquake.Results：The sound wall has no deformation during and after the tsunami action. In the wall with some opening, around 30 minutes after the start of the tsunami action, the wall panel showed gradual deviations such as slippage. In all cases, the pore water pressure in the backfill soil rises with seepage of the water, but the soil was not completely saturated.Conclusions：It was found that a reinforced soil wall does not have large deformation unless there are some opening of the front panels and the backfill soil flow out of the wall. This result shows that reinforced soil wall does not collapse by seepage to the backfill soil or wave force of tsunami, but collapses by backfill soil flowing out from wall surface. Our results support that a reinforced soil wall has high tsunami-resistance. Given this information, it is necessary to prevent the wall from making some opening and prevent the backfill soil from flowing out.

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MODELING OF THE COMPACTION-INDUCED STRESSES IN NUMERICAL ANALYSES OF GRS WALLS

International Journal of Computational Methods ◽

10.1142/s0219876213420024 ◽

2014 ◽

Vol 11 (02) ◽

pp. 1342002 ◽

Cited By ~ 15

Author(s):

S. H. MIRMORADI ◽

M. EHRLICH

Keyword(s):

Soil Layer ◽

Numerical Approach ◽

Reinforced Soil ◽

Suggested Procedure ◽

Geosynthetic Reinforced Soil ◽

Induced Stress ◽

Reinforced Soil Wall ◽

Backfill Soil ◽

Parametric Studies ◽

Induced Stresses

This article presents a numerical approach for modeling of the compaction-induced stresses on the analyses of geosynthetic reinforced soil (GRS) walls. The modeling of the backfill compaction stresses was described and analyses were performed using this suggested procedure. Two distribution loads at the top and bottom of each soil layer were used to simulate the vertical induced stress due to backfill soil compaction. The suggested procedure was validated with the results of a wrapped-faced full-scale reinforced soil wall performed at the Geotechnical Laboratory of COPPE/UFRJ. The results of the simulation using this procedure were compared with another procedure reported in the literature. Parametric studies were carried out to verify the effect of compaction induced stress and surcharge loads on the behavior of GRS walls. Results show that the compaction procedure suggested in the present paper was able to properly represent the measured values of the summation of the maximum tension in the reinforcement and lateral movements. It was verified that the compaction procedure used in the literature overestimated the measured values, and this discrepancy increases with depth and also with compaction effort.

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