Performance of Mechanically Stabilized Earth Structures When Subjected to Passive Forces
Type of DegreePhD Dissertation
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Mechanically stabilized earth structures are increasing in popularity due to their relative ease of construction and favorable performance. Current mechanically stabilized earth designs consider only active pressures acting on the structure. Previous research has been performed to model or measure the passive (laterally compressive) forces that are exerted on mechanically stabilized abutments due to thermal expansion of a bridge deck. While such research measures the magnitude of passive forces applied to mechanically stabilized earth structures, it fails to address the performance of the mechanically stabilized structure when subjected to these forces. As such, a knowledge gap exists. This research fills this knowledge gap by providing insight into the performance of such structures when subjected to passive forces, allowing this technology to be implemented in a wider variety of applications that can now include passive forces in addition to active forces. This research evaluates the performance of model mechanically stabilized earth structures through a laboratory testing program consisting of instrumented, scale tests where passive strain is applied to specimens with varying reinforcement schemes. Finite difference modeling was used to simulate the laboratory testing program. The primary aspect of performance evaluated is the load-deformation response when presence, length, width, and vertical spacing of reinforcement are varied. The secondary aspect of performance evaluated is the location of the passive failure surface in the soil with respect to the previously described reinforcement variances. The load-deformation response is quantified by measuring the following four key elements: Peak Force, displacement where Peak Force occurred, Residual Force, and stiffness at 50% of the Peak Force (K50). The addition of reinforcement to a soil structure causes a decrease in Peak Force values, an increase in K50 values, and a non-determinate effect on Peak Force Displacement and on Residual Force. Among reinforced specimens, increasing the reinforcement surface area results in increased Peak Force, Residual Force, and K50 values, as well as decreased Peak Force Displacement values. Increased vertical spacing tended to produce longer failure surfaces.