Analysis and modeling of the response of geotextile-reinforced soil to monotonic and cyclic loading
Abstract
The constitutive behavior of geosynthetic-reinforced soil masses under repeated loading is not yet fully understood. Cyclic loading conditions occur due to traffic in transportation infrastructures such as reinforced unpaved (access) and paved roads, roadway and railway embankments, railway ballast, and bridge abutments. Due to the lack of knowledge on the cyclic response of geosynthetic-reinforced materials, a detailed investigation is described in this dissertation. The testing program consists of direct shear tests on the soil-geotextile interface, as well as monotonic and cyclic triaxial tests on the reinforced soil and on the geotextiles in-isolation. A silty material is used for the baseline case. Scale effects are investigated by testing 150 mm (6") diameter specimens in addition to the baseline 70 mm (2.8"). Test results indicate that significant improvement in strength is achieved due to the inclusion of geosynthetics. When loaded monotonically, the reinforced soil shows continuous increase in strength with increasing strain level. Under cyclic loading, the permanent deformation corresponding to a constant peak load depends on the reinforcement spacing, the load amplitude, the soil-geotextile interface properties, the specimen size, and to a much lesser extent on the reinforcement modulus. Visual observation and numerical analyses suggest that the effect of the geotextile modulus on the response is insignificant for both monotonic and cyclic cases. Close examination of the reinforced specimens after the tests indicate that more sliding occurs at the interface under cyclic conditions, which implies that a large portion of the interface strength is mobilized. Three analytical models are developed to interpret the test results. Two of them are based on strain normalization concepts, and account for scale effects. The third method relates the number of cycles to the cyclic and monotonic stresses at a given strain. Numerical modeling of the reinforced soil specimens allows for better understanding of the actual state of stress within the soil and along the interface. The analytical models, together with the numerical analysis provide a useful tool for analysis and design of geosynthetic-reinforced soil structures subjected to monotonic and repeated loading.
Degree
Ph.D.
Advisors
Bourdeau, Purdue University.
Subject Area
Civil engineering|Geotechnology|Soil sciences
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