In the field of civil engineering, particularly structural foundations, low-cost options and time saving construction methods are important because both can be a burden on the public. Drilled shafts have proven to both lower cost and shorten construction time for large-scale projects. However, their integrity as load-carrying foundations has been questioned. The statnamic load test was conceived in the 1980s as an alternative method of testing these larger, deeper foundation elements. Performing a load test verifies that the load carrying capacity of a foundation is agreeable with the estimated capacity during the design phase and that no significant anomalies occurred during construction. The statnamic test, however, is classified as a rapid load test and requires special data regression techniques. The outcome of available regression techniques is directly related to the available instrumentation on the test shaft. Generally, the more instrumentation available, the more complete results the regression method will produce. This thesis will show that a proposed method requiring only basic instrumentation can produce more complete results using a predictive model for side shear development with displacement during the statnamic test. A driven pile or drilled shaft can be discretized into segments based on the load shed distribution model. Each segment can be analyzed as a rigid body. The total static capacity is then the summation of each segments’ contribution. Further, a weighted acceleration can be generated and used to perform an unloading point analysis.

There are over 602,000 bridges in the United States, of which 12.5% are classified as functionally obsolete and 11.2% are structurally deficient. The functionally obsolete bridges will require expansion or replacement to increase the service capacity of the bridge. The structurally deficient bridges will either need remediation of the load carrying elements which are damaged or deteriorated or will need to be replaced completely. Replacement of the bridges means new construction; new construction means better design and quality assurance to meet the 100+ year service life requirement in place now. Rehabilitation of bridges will require better design and quality assurance to increase the current service life of the structure. This dissertation presents new design, testing, and repair methods developed to extend the life of new and existing bridges through pressure grouting, thermal integrity testing of drilled shafts, and the bond enhancement of fiber reinforced polymer (FRP) repair materials bonded to concrete with vacuum bagging and pressure bagging, respectively. Pressure grouting of drilled shaft tips has been used for over five decades to improve the end bearing capacity, but no rational design procedure had ever been published until this study. The research outlined in this dissertation analyzed nine grouted shafts and compared them to standard design procedures to determine the improvement in end bearing. Improvements ranged from 60% to 709% increase in end bearing capacity. From these improvements, a design procedure was developed for pressure grouted drilled shafts. Post construction inspection of drilled shafts relies largely on non-visual techniques dealing with measured concrete quantities, acoustic wave speed or frequency, gamma radiation attenuation and now the internal temperature of the curing concrete. Thermal Integrity Profiling (TIP), developed at USF, utilizes the heat of hydration of curing concrete to evaluate the concrete cover, foundation shape, cage alignment, and concrete mix design performance. This research developed standard test equipment and procedures for thermal integrity testing. Comparing the results of the different types of integrity tests is difficult due to the varied nature of the different tests. The dissertation looked at various shafts constructed across the nation which were tested with thermal and at least one other integrity test method. When compared to acoustic and gamma radiation test results, TIP agreed with 4 of 6 cases for acoustic and 2 of 5 cases using gamma radiation. In the one case were both sonic caliper and inclination data were available, TIP showed good agreement. Vacuum bagging and pressure bagging are techniques for improving the FRP-concrete bond in the repair of partially submerged piles. Prototype vacuum bagging and pressure bagging systems were developed and bond improvement assessed from results of pullout tests on full size piles repaired under simulated tidal exposures in the laboratory. Pressure bagging gave better bond and was found to be simpler because it did not require an airtight seal. A field demonstration project was conducted in which pressure bagging was used in combination with two different glass FRP systems to repair two corroding piles supporting the Friendship Trails Bridge across Tampa Bay. Inspection of the post-cured wrap showed no evidence of air voids.

Geothermal energy is an energy source with potential to supply mankind with both heat and electricity in nearly unlimited amounts. Despite this potential geothermal energy is not often considered in the general energy debate, often due to the perception that it is a margin energy source bound to a few locations with favorable geological conditions. Today, new technology and system concepts are under development with the potential to extract geothermal energy almost anywhere at commercial rates. The goal of these new technologies is the same, to harness the heat stored in the crystalline bedrock available all over the world at sufficient depth. To achieve this goal two major problems need to be solved: (1) access to the depths where the heat resource is located and (2) creation of heat transferring surfaces and fluid circulation paths for energy extraction. In this thesis a novel concept and method for both access and extraction of geothermal energy is investigated. The concept investigated is based on the earlier suggested idea of using a main access shaft instead of conventional surface drilling to access the geothermal resource, and the idea of using mechanically constructed 'artificial fractures' instead of the commonly used hydraulic fracturing process for creation of heat extraction systems. In this thesis a specific method for construction of such suggested mechanically constructed heat transfer surfaces is investigated. The method investigated is the use of diamond wire cutting technology, commonly used in stone quarries. To examine the concept two heat transfer models were created to represent the energy extraction system: an analytical model based on previous research and a numerical model developed in a finite element analysis software. The models were used to assess the energy production potential of the extraction system. To assess the construction cost two cost models were developed to represent the mechanical construction method. By comparison of the energy production potential results from the heat transfer models with the cost results from the construction models a basic assessment of the heat extraction system was made. The calculations presented in this thesis indicate that basic conditions for economic feasibility could exist for the investigated heat extraction system.

The transformation of Joint forces to be lighter, more lethal, and capable of deploying from multiple dispersed locations free of prepared landing zones requires a dedicated heavy lift VTOL aircraft capable of rapidly delivering large payloads, such as the 20 to 26 ton Future Combat System, at extended ranges in demanding terrain and environmental conditions. Current estimates for a single main rotor configuration place the design weight over 130,000 pounds with an installed power of approximately 30,000 horsepower. Helicopter drive systems capable of delivering torque of this magnitude succeeded in the Russian Mi-26 helicopters split-torque design and the Boeing VERTOL Heavy Lift Helicopter (HLH) prototypes traditional multi-stage planetary design. The square-cube law and historical trends show that the transmission stage weight varies approximately as the two-thirds power of torque; hence, as the size and weight of the vehicle grows, the transmissions weight becomes an ever-increasing portion of total gross weight. At this scale, optimal gearbox configuration and component design holds great potential to save significant weight and reduce the required installed power. The drive system design methodology creates a set of integrated tools to estimate system weight and rapidly model the preliminary design of drives system components. Tools are provided for gearbox weight estimation and efficiency, gearing, shafting, and cooling. Within the same architecture, the designer may add similar tools to model subcomponents such as support bearings, gearbox housing, freewheeling units, and rotor brakes. Measuring the relationships between key design variables and system performance metrics reveals insight into the performance and behavior of a heavy lift drive system. A parametric study of select design variables is accomplished through an intelligent Design of Experiments that utilizes Response Surface Methodology to build a multivariate regression weight model. The model permits visualization of the design space and assists in optimization of the drive system preliminary design. This methodology is applied to both the Boeing HLH and the Russian Mi-26 main gearboxes. This study applies the drive system design methodology to compare the Mi-26 split-torque gearbox over the Boeing HLH multi-stage planetary gearbox in a single main rotor heavy lift helicopter.

During the three decades, the torsional impact on turbine-generator sets due to power system disturbances has been extensively discussed in many research works. However, most of them are focused on the fatigue damage of turbine shafts due to large-signal disturbances. For example, network faults occur. Obviously, the torsional effect subject to small-signal disturbances has not received much attention. In fact, although the small disturbances would not immediately damage the turbine mechanism, the cumulative long-term damaging effects may not be negligible under certain circumstances. Many operating conditions in power systems may lead to small disturbances on blades; for examples, shedding loads, switching transmission line, resetting control system parameters, and harmonics etc. Nevertheless, others only cause short-term or transient non-resonant disturbances occasionally except the power system subharmonics which could results in electro-mechanical resonance. Therefore, two types of subharmonics in power systems are proposed so as to investigate the toque impact and long-term fatigue life expenditure in turbine shafts and blades. Firstly, from the steady-state disturbance viewpoint, the long-term cumulative fatigue estimation based on the three-year project of the GE Co. shows that there are potential damages for both the shafts and the blades of the nearby generators caused by the subharmonic excitations of the HVDC link. The fatigue life sensitivity works are also carried out to provide the recommendations for the safety operation. The optimal damper type and disposition scheme for depressing the resonant torque and prolonging the turbine lifetime is consequently motivated, which is based on participation factor of linear systems with the electromechanical analogy. The effectiveness of this scheme on suppressing vibration torque arising from network faults is also satisfying. In addition, the authors propose the new electromechanical supersynchronous resonance phenomenon for the turbine-generators near the inverter station owing to asymmetric line faults near the rectifier station. Secondly, the dramatic real and reactive power consumption during the melting period of an electrical arc furnace load. The voltage flicker pollution is mainly caused by the reactive power fluctuation while the stochastic subsynchronous oscillation in turbine mechanism is excited by the electromagnetic torque of the subsynchronous frequency which is induced by the real power fluctuation. Such a small stress imposed on the low-pressure long turbine blade combined with its evitable corrosive environment contributing to the corrosion fatigue effect. Although the voltage flicker severity at the point of common coupling is still within the limit, the blade may have been damaged from the long-term corrosion fatigue life expenditure estimation. In other words, the conventional voltage flicker limit established to make human-eye comfortable might not protect the blade from damaging risk. The long-term influence resulted from the electric arc furnace loads cannot always be neglected. It is necessary to take care of the blade material intensity and operating environment. If there is the potential of blade damage, one has to strengthen the output capacity at the power plant or separate the peak load durations among the steel plants to limit the over-fluctuation real power of the generator.

In recent years, extensive studies on alternative fuels have been conducted to find environmentally friendly, economically feasible fuels due to finite petroleum sources, environmental and economical reasons. In this thesis, effects of alternative fuels on engine performance and exhaust emission are studied experimentally. Cold and reacting tests have been performed. Volumetric flow rate, discharge pressure are measured according to different pump speed. Droplet diameters, droplet distribution, spray cone angle and two dimensional velocity distribution from combustor fuel nozzle are determined by IPI and PIV technique. The comparative performance of alternative fuels and JET A-1 are investigated by atmospheric combustion tests and experimental turbojet tests in terms of exhaust gas temperatures, emissions, combustion chamber efficiency. Emissions, combustion chamber exit temperature profile, power turbine inlet and exhaust gas temperatures, effects of fuels on engine performance are observed and measured in detail at RR Allison 250 C-18 turbo-shaft engine.

Drilled shaft construction often requires the use of drill slurry to maintain borehole stability during excavation and concreting. While drill slurry may be composed of fluids ranging from air to petroleum, drilled shaft construction typically makes use of water based drilling fluids. Although clean water may be utilized as a drilling fluid, a premixed slurry consisting of water, minerals, and/or polymers is more commonly used. Florida Department of Transportation (FDOT) specifications require the use of mineral slurry for all primary structures. The slurry resists the intrusion of groundwater, slows the outward migration of drilling fluid from the excavation, and aids in the removal of suspended soil cuttings. The mechanisms by which mineral slurries work are quite different from those of polymer slurries. Due to these differences, it is unclear whether a mineral based slurry, which has been fortified with polymers by manufacturers or enhanced through the addition of polymers in the field, behaves more like a mineral slurry rather than polymer slurry. This thesis provides an overview of the methods used to measure physical slurry parameters of interest. These parameters include density, viscosity, pH, sand content, and filtration control. Methods employed to describe the slurry parameters include tools and instrumentation commonly used in both field and laboratory settings.

Recent interest in "greener" geothermal heating and cooling systems as well as developments in the quality assurance of cast-in-place concrete foundations has heightened the need for properly assessing thermal properties of soils. Therein, the ability of a soil to diffuse or absorb heat is dependent on the surrounding conditions (e.g. mineralogy, saturation, density, and insitu temperature). Prior to this work, the primary thermal properties (conductivity and heat capacity) had no correlation to commonly used soil exploration methods and therefore formed the focus of this thesis. Algorithms were developed in a spreadsheet platform that correlated input boring log information to thermal properties using known relationships between density, saturation, and thermal properties as well as more commonly used strength parameters from boring logs. Limited lab tests were conducted to become better acquainted with ASTM standards with the goal of proposing equipment for future development. Finally, sample thermal integrity profiles from cast-in-place foundations were used to demonstrate the usefulness of the developed algorithms. These examples highlighted both the strengths and weaknesses of present boring log data quality leaving room for and/or necessitating engineering judgment.

Strut-and-tie modeling (STM) is a versatile, lower-bound (i.e. conservative) design method for reinforced concrete structural components. Uncertainty expressed by engineers related to the implementation of existing STM code specifications as well as a growing inventory of distressed in-service bent caps exhibiting diagonal cracking was the impetus for the Texas Department of Transportation (TxDOT) to fund research project 0-5253, D-Region Strength and Serviceability Design, and the current implementation project (5-5253-01). As part of these projects, simple, accurate STM specifications were developed. This thesis acts as a guidebook for application of the proposed specifications and is intended to clarify any remaining uncertainties associated with strut-and-tie modeling. A series of five detailed design examples feature the application of the STM specifications. A brief overview of each design example is provided below. The examples are prefaced with a review of the theoretical background and fundamental design process of STM (Chapter 2). • Example 1: Five-Column Bent Cap of a Skewed Bridge - This design example serves as an introduction to the application of STM. Challenges are introduced by the bridge’s skew and complicated loading pattern. A clear procedure for defining relatively complex nodal geometries is presented. • Example 2: Cantilever Bent Cap - A strut-and-tie model is developed to represent the flow of forces around a frame corner subjected to closing loads. The design and detailing of a curved-bar node at the outside of the frame corner is described. • Example 3a: Inverted-T Straddle Bent Cap (Moment Frame) - An inverted-T straddle bent cap is modeled as a component within a moment frame. Bottom-chord (ledge) loading of the inverted-T necessitates the use of local STMs to model the flow of forces through the bent cap’s cross section. • Example 3b: Inverted-T Straddle Bent Cap (Simply Supported) - The inverted-T bent cap of Example 3a is designed as a member that is simply supported at the columns. • Example 4: Drilled-Shaft Footing - Three-dimensional STMs are developed to properly model the flow of forces through a deep drilled-shaft footing. Two unique load cases are considered to familiarize the designer with the development of such models. / text

South Africa is one of the world's foremost mining nations and mining and its associated industries continue to form the cornerstone of the country's economy. However, the mining industry has, by its very nature, the potential to endanger human health and safety, as well as the physical environment. Consequently, mining will always contend with major environmental challenges and remain under constant public pressure to demonstrate its commitment to responsible environmental management. The key to effective environmental management is the use of a systematic approach to plan, control and improve environmental efforts. An Environmental Management System (EMS) employs such an approach and allows organisations to address environmental concerns in an orderly and consistent manner. Such a system allows organisations to anticipate and meet their environmental objectives and to ensure ongoing compliance with national and/or international requirements. An organisation with no existing EMS should, initially, establish its current position with regard to the environment by means of an initial review process. The aim should be to consider all environmental aspects of the organisation as a basis for establishing the EMS. Although a few gold mines in South Africa have implemented an EMS, the question of which significant environmental aspects need to be managed in such a system at a deep level gold mine shaft, remains largely unanswered. This study endeavoured to provide answers to this question and develop a generic model for the initial review process of a deep level gold mine shaft. The development of such a model should facilitate the development and implementation of an EMS at such shafts, thereby contributing to reduce the environmental impact of gold mines. The research consisted of a literature review of national and international literature on the topic and a comparative empirical study, which evaluated the mining operations of two deep level gold mine shafts. Data collection and analysis was done according to the IS0 14015 guideline on the environmental assessment of sites and organisations. Other techniques used included business process analysis, the use of modified Leopoldt matrices and risk analysis to determine the significance of the environmental impacts and aspects. This study contributed to a generic model for the initial environmental review process that precedes the development of an EMS at deep level gold mine shafts through: developing a generic sub-model that can be used to determine the scope of any deep level gold mine shaft; identifying some of the significant environmental impacts and aspects of deep level gold mine shafts, as well as identifying some generic business activities that are potentially destructive and carry a high risk of causing significant negative environmental impacts. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2004.