Pile foundations near the crest of a slope are often required to resist lateral loads. This is particularly important for piles at the abutments of bridges. However, limited full-scale test data are available to indicate how the lateral resistance of a pile would be affected when it is located near the crest of a slope. To investigate the effect of a slope on lateral pile resistance, three full scale lateral load tests were conducted on an instrumented steel pipe pile. For the first test, the pile was laterally loaded in horizontal ground. For the second test the pile was at the crest of a 30 degree slope and in the third test the pile was placed three diameters behind the crest of the 30 degree slope. The soil around the pile consisted of clean sand compacted to about 95% of the modified Proctor maximum unit weight for all three tests. Laboratory and in-situ direct shear tests indicated that the friction angle of the sand was approximately 39 degrees. The pile was instrumented with strain gages at approximately 1.5 ft intervals along its length so that the bending moment versus depth profile could be determined. Pile head load, deflection, and rotation were also measured. Based on the results, the presence of the slope decreased the ultimate lateral resistance of the pile-soil system by approximately 25% and 10% for tests two and three, respectively. The presence of the slope also resulted in an increase in the maximum bending moment of approximately 40% and 30% for tests two and three, respectively. Analyses using LPILE matched the lateral resistance for the pile in horizontal ground, but significantly overestimated the decrease in resistance due to the sloping ground. A mathematical model was developed to predict the ultimate strength of a pile located some distance from the crest of a cohesionless sloping profile. Parametric test results using the model were within 2.6 % of the measured results of tests two and three.

No description available.

Scour is a process of removing soils around foundations by currents and waves. For the pile-supported marine structures such as the monopile-supported offshore wind turbines (OWTs) and the pile-supported bridges, scour can decrease the pile capacities and alter the dynamic responses of the structures. At present, there is not a widely accepted method to estimate pile axial or lateral capacity under scoured conditions. For example, different recommendations are used among the existing design standards for estimation of the vertical effective stress and the resulting capacities for single piles under different scour conditions. None of the existing standards or design practice has even considered the scour effects on the behavior of pile groups. Furthermore, the investigation into the responses of piles under multiple hazards of scour and earthquakes is rarely reported. To address the foregoing limitations, this study first introduces an analytical solution to determining the vertical effective stress of soils around single isolated piles under scoured conditions and uses it to examine the limitations of the existing standards in estimation of pile tensile capacity (Chapter 1). The effect of soil-pile interface friction is highlighted. Next, the study proposes new approaches to investigating the combined effects of scour and earthquakes on the lateral responses of the monopile-supported OWTs in sand (Chapter 2) and soft clay (Chapter 3). Lastly, simple and practical methods are developed based on the p-y curve framework for analyzing the lateral responses of pile groups in sand (Chapter 4) and soft clay (Chapter 5) subjected to static lateral loading. The proposed methods in this study were encoded into a series of open-source computer scripts for engineering practice. They were verified with the 3D continuum finite element (FE) analyses. Using the proposed methods, standard methods, and 3D FE method, parametric analyses were conducted to investigate the scour effects on the lateral behavior of the monopile-supported OWTs under crustal earthquakes and that of the pile groups under static loading. The factors considered in the parametric study included effects of scour-hole dimensions, soil stress history, soil density, soil-pile interface behavior, soil liquefaction potential, pile group configurations, etc. Through the parametric analyses, the standard methods were critically assessed by comparing the results to those calculated by the proposed methods and 3D FE methods, and some design-related issues were also discussed. / Graduate