Study of the influence of global soil stifness due to wetting on the behavior of geosynthetic reinforced structures

• Grant number: 16/24035-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2017
• End date: September 30, 2017
• Field of knowledge: Engineering - Civil Engineering - Geotechnical Engineering
• Principal Investigator: Fernando Henrique Martins Portelinha
• Grantee: Lucas Matheus Do Nascimento
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Retaining walls using the soil reinforced technique has been expanded in the geotechnical engineering due to technical and economical advantages when compared to other conventional solutions as concrete and gabion walls. The use of local fine-grained soils as backfill material with geosynthetic reinforcements has provided even more cost savings, versatibility and environmental conservation. In design analyses, the distribution of stresses in each reinforcement layer and interaction between soil and geosynthetics has been the main parameters to be considered. The soil, which is normally compacted at the optimum moisture content of Proctor, is susceptible to variations on the mechanical properties during service due to different source of wetting. Considerations of these wetting effects has been difficult to be considered in analyses. Normally, the stresses and strains predictions are based on extreme conditions of soil saturation resulting in source of conservadorism or inconsistencies when compared to actual behavior in field. Many instrumented cases have reported the backfill soil rarely reachs the saturation condition under advancement of wetting into the reinforced zone maintaing the unsaturated condition of the soil. However, the understanding of the advancement of wetting and its effect on the performance of a geosynthetic reinforced soil wall is of significant importance. Additionally, it is also relevant the search for methods that permits the consideration of this phenomena in design analyses. Accordingly, this study evaluates the effect of different sources of wetting into a geosynthetic reinforced soil wall, e.g. as those due to rainfalls (top-down), capillary rising, facing wetting and other. The study will be carried out using the finite element software PlaxisV8, considering only the effect of the wetting on the reduction of uction and the unit weight of soil, as well as the reduction of stiffness and shear strength of soil under unsaturated conditions. Na instrumented case history (Bairro Novo/Campinas) will be numerically modeled and will be used for the analyses of wetting. Concepts of unsaturated soil mechanics will also be extensively used in this study. (AU)