Estimating the earth pressures applied on drilled shaft retaining walls in expansive clays is challenging due to the soil's tendency to shrink and swell under cycles of moisture fluctuation. While empirical suggestions do exist, significant uncertainty exists regarding the effect of volumetric changes of the soil on the earth pressures. In order to investigate this uncertainty, a fully instrumented drilled shaft retaining wall named in the honor of Lymon C. Reese, was constructed in the highly expansive clay of the Taylor formation. Inclinometers and optical fiber strain gauges were installed in three instrumented shafts and time domain reflectrometry sensors were placed within the soil to measure changes in the moisture content. Nearly two years of monitoring data have been obtained which are used to estimate the earth pressure distribution at different moisture conditions. Processing of the raw strain data was required to eliminate the effects of tension cracks and other microscale factors that caused significant variation in the results. Good agreement was obtained between the processed strain and inclinometer data as the deflected shapes predicted from both monitoring elements were similar. Finally, the earth pressure distribution for six dates that represent different moisture conditions of the Taylor clay were plotted and the results of the strain gauge and inclinometer analysis were consistent. A p-y analysis was also conducted to estimate the range of earth pressures applied on the wall. A triangular earth pressure diagram was used as external load above the excavation level and the equivalent fluid pressure was evaluated by matching the deflected shapes generated from the inclinometer data to those predicted by the p-y model. The results were compared to the empirical values that TxDOT uses for design of similar type of walls in expansive clay. Finally, the side shear and temperature effects on the lateral response of the wall were quantified. A differential linear thermal model was used to evaluate the temperature effects and a t-z analysis was conducted to account for the side shear applied on the wall due to volumetric changes of the soil. It is recommended that their combined effect be considered in the design. / text

Tieback walls are typically design based on predetermined pressure distribution; however, these pressures were proposed based on performance of excavations. For retaining walls used in slope remediation, the application of these pressures might not be adequate; the construction procedure; therefore, a different response of the wall is expected. This document, presents the performance of two tieback walls installed in a shale stratum. Monitored responses is correlated with construction activities; these activates implied excavation and backfilling in both of the tieback walls. In addition, this research shows a numerical procedure to evaluate the anchor capacity based on the t- z approach. Finally, this study introduces an empirical method to estimate lateral wall deformation profiles and internal bending moments along a retaining wall installed in a clay stratum.

Large diameter piles are widely used as foundations to support buildings, bridges, and other structures. As a result, it is critical for the field to have an optimized approach for quality control and efficiency purposes to measure the suggested number of load tests and the required measured capacities driven piles. In this thesis, an analysis of a load test program designed for proposed bridge replacements at Kentucky Lake is performed. It includes a detailed site exploration study with in-situ and laboratory testing. The pile load test program included monitoring of a steel H-pile and steel open ended pipe pile during driving and static loading. The pile load test program included static and dynamic testing at both pile testing locations. Predictions of both pile capacities were estimated using commonly applied failure criterion, and a load transfer analysis was carried out on the dynamic and static test data for both piles. The dynamic tests were then compared to the measured data from the static test to examine the accuracy. This thesis concludes by constructing t-z and q-z curves and comparing the load transfer analyses of the static and dynamic tests.

Ground anchors represent an important structural element in the area of ground engineering. Despite an extensive usage of these elements, their design is usually performed using simple empirical and semi-empirical methods. An application of these procedures brings to the design a number of simplifying assumptions. The goal of the dissertation is to refine the computational design of ground anchors, analysis and quantification of selected factors significantly affecting their load displacement behavior. Firstly, the finite element method is applied. Two novel constitutive models are used: Multilaminate Constitutive Model for Stiff Soils (Schädlich, 2012) involving post peak shear softening of overconsolidated cohesive soils and Shotcrete Model (Schädlich, 2014) involving tension softening after tensile strength is reached. First constitutive model was used in order to simulate progressive decrease of skin friction along the anchor fixed length. Second constitutive model was applied for the grout material. In the next step, experimental program including several anchor load tests was carried out. The goal of the experimental program was to confirm conclusions from numerical studies and to obtain relevant data for further back – analysis. A newly developed application, in which all the findings from numerical computations and experimental measurements are incorporated, is described afterwards. The application is based on the use of so-called load-transfer functions. The program verification was conducted through series of back analysis of investigation anchor load tests realized on four different construction sites in two different types of fine-grained soils. The verification of the application is followed by series of parametric studies in which an influence of input parameters values is analyzed. Dissertation is concluded by the summarization of the most important findings.

Bridge failures in the past decade due to structural deficiencies demonstrated the clear need for a review of the current bridge analysis approaches. This study focuses on pile-supported bridges under predominantly static loading. A critical review of the current analysis approaches was performed. It was concluded that in the absence of an onerous iteration process, the current approaches often produce inaccurate and, in many cases, unsafe results since the interactions between superstructure and foundation are not fully considered. To address the inherent limitations of the current approaches, a computer program [Soil Spring Module (SSM) 2.0] was developed as a part of the study. SSM 2.0 can be used in conjunction with a frame analysis program to capture nonlinear load transfer from foundation elements to soil in different directions simultaneously. STAAD.Pro was selected for demonstration in this study. Using SSM 2.0 and STAAD.Pro, this study proposes a new analysis approach using the Integrated Analysis Process (IAP). The same methodology can be applied in other frame analysis programs. Kansas Bridge 45 was selected as a case study. Using the IAP approach, a series of integrated analyses including all superstructure elements (e.g., deck, girders and piers) and all foundation elements (e.g., pile caps and piles) were performed on Kansas Bridge 45 for different soil types and properties. Different from the conventional approaches, the full interactions between superstructure and foundation were considered simultaneously in a single analysis using the IAP approach. The analysis results from the IAP approach and the conventional approaches were examined. The advantages of the IAP approach were identified. Comparing to the conventional approaches in current practice, the proposed IAP approach does not involve crude assumptions or intensive iterations. Using the IAP approach, design engineers can complete structural and foundation analysis of pile-supported bridges with good accuracy in a timely manner. The same methodology can potentially be applied to other structure types. / Graduate / 2022-12-15