Composite Behavior of Geosynthetic Reinforced Soil Mass

This study investigated the composite behavior of a geosynthetic reinforced soil (GRS) mass. Many studies have been conducted on the behavior of GRS structures; however, the interactive behavior between the soil and geosynthetic reinforcement in a GRS mass has not been fully elucidated. Current design methods consider the reinforcement in a GRS structure as tiebacks and adopt a design concept that the reinforcement strength and reinforcement spacing produce the same effects on the performance of a GRS structure. This has encouraged designers to use stronger reinforcement at a larger spacing to reduce time and effort in construction. A series of large-size generic soil geosynthetic composite (GSGC) tests were designed and conducted to examine the behavior of a GRS mass under well-controlled conditions. The tests clearly demonstrated that reinforcement spacing has a much stronger impact than reinforcement strength on the performance of the GRS mass. An analytical model was established to describe the relative contribution of reinforcement strength and reinforcement spacing. Based on the analytical model, equations were developed to calculate the apparent cohesion of a GRS composite, the ultimate load-carrying capacity of a GRS mass, and the required tensile strength of reinforcement for a prescribed value of spacing. The equations were verified using measured data from the GSGC tests and measured data from large-size experiments by other researchers, as well as by results of the finite element (FE) method of analysis. Due to the popularity of GRS walls with modular block facing, an analytical procedure was developed for predicting the walls’ lateral movement. This procedure also allows the required tensile strength of the reinforcement to be determined by simple calculations. In addition, compaction-induced stresses, which have usually been ignored in design and analysis of GRS structures, were investigated. An analytical model for estimating compaction-induced stresses in a GRS mass was proposed. Preliminary verification of the model was made by using results from the GSGC tests and FE analysis. The dilative behavior of a GRS composite was also examined. The presence of geosynthetic reinforcement has a tendency to suppress dilation of the surrounding soil and reduce the angle of dilation of the soil mass. The dilative behavior offers a new explanation of the reinforcing mechanism, and the angle of dilation may be used to reflect the degree of reinforcing of a GRS mass.\n