| dc.description.abstract | Mechanically stabilized earth (MSE) walls have been wildly used in various important infrastructures, such as bridge abutments. The need for a shallow or deep foundation in an MSE wall for bridge support has been increasing. Different types of piles are used for this purpose, but the effect of their location within the MSE wall system is not fully investigated. In fact, there are no accepted design methods or procedures for piles in MSE walls. So far, limited full-scale studies have been conducted to evaluate the behavior of a laterally loaded pile within an MSE wall. In this study, the factors influencing performance of laterally loaded piles in MSE walls were investigated in the laboratory using reduced-scale models. Eighteen model tests were conducted in this study. The influence factors investigated in this study included pile offset, wall height, reinforcement length and spacing, and geogrid-wall facing connection. Three pile offset distances were chosen: 127, 254, and 381 mm. Two wall heights of 450 and 720 mm were considered. The regular reinforcement length was equal to 315 mm for low wall tests while that was 504 m for the high wall tests. In addition, a long reinforcement length of 900 mm was considered. Moreover, two reinforcement spacing of 90 and 135 mm were used. Finally, mechanical connection and frictional connection were used in this study. In order to investigate the effect of the pile offset, the model tests were designed in three groups. Group 1 had three tests with low walls, three different pile offsets, regular reinforcement length, small reinforcement spacing, and mechanical connection between wall facing and geogrid. Group 2 includes three categories. Category 1 of Group 2 had three tests with high walls, three different pile offsets, regular reinforcement length, large reinforcement spacing, and mechanical connection. Category 2 of Group 2 had three tests with high walls, three different pile offsets, regular reinforcement length, small reinforcement spacing, and mechanical connection. Category 3 of Group 2 had three tests with high walls, three different pile offsets, regular reinforcement length, small reinforcement spacing, and frictional connection between geogrid and wall facing. Group 3 also includes three categories. Category 1 of Group 3 had two tests with high walls, two large pile offsets, long reinforcement length, large reinforcement spacing, and mechanical connection. Category 2 of Group 3 had two tests with high walls and two large pile offsets, long reinforcement length, small reinforcement spacing, and mechanical connection. Category 3 of Group 3 had two tests with high walls, two large pile offsets, long reinforcement length, small reinforcement spacing, and frictional connection. In addition, eighteen tests of this study were grouped into eight comparison sets to investigate the effects of wall height, reinforcement length and spacing, and geogrid-wall facing wall connection. Each set had two or three tests with different pile offsets. In addition to the change of pile offset, each set had one factor varied to investigate its effect. The study results and comparisons show that the increase of the pile offset reduced the lateral deflections of the pile and the lateral deflections of wall facing along the vertical centerline. The increase of the wall height and the reinforcement length increased the pile capacity and reduced the lateral deflections of wall facing along the vertical centerline. The increase of the reinforcement spacing reduced the pile capacity and increased the lateral deflections of wall facing along the vertical centerline. The change of the geogrid-wall connection from fictional connection to mechanical connection increased the capacity of the pile especially for the long reinforcement tests. The pressure behind the upper part of the wall facing increased by the decrease of the pile offset while the pressure behind the lower part of the wall facing increased by the decrease of the reinforcement length. Finally, pile location within the maximum tensile zone of the geogrid layer is a critical factor that affects the geogrid strain. | |
