published_or_final_version / abstract / toc / Civil Engineering / Master / Master of Philosophy

Collapse in soils occur when a partially unstable, partially saturated open fabric under high enough stress causing a metastable structure with large soil suction, or in the presence of a bonding or cementing agent, is allowed to free access to additional water. Such excess water reduces soil suction and weakens or destroys the bonding, this causing shear failure at the interaggregate or intergranular contacts, consequently, the soil collapses. In this study, the collapsible soils found in the &Ccedil / ayirhan Thermal Power Plant area has been stabilized by using the desulphogypsum, and fly ash obtained from the &Ccedil / ayirhan Thermal Power Plant. An extensive laboratory testing program has been undertaken to provide information on the geotechnical properties of collapsible soil treated by &Ccedil / ayirhan fly ash and desulphogypsum. At the end of the test program, it has been seen that the collapsible soil (compacted) can be stabilized by adding fly ash and desulphogypsum. Although a significant change on the collapse potential was not observed when fly ash and desulphogypsum added samples were compared with compacted sample without stabilization, but there is an increase in unconfined compressive strength values due to stabilization.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 241-249). Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--Florida State University, 2006. / Advisor: Jeffrey Chanton, Florida State University, College of Arts and Sciences, Dept. of oceanography. Title and description from dissertation home page (viewed Sept. 26, 2006). Document formatted into pages; contains ix, 84 pages. Includes bibliographical references.

L’histoire de l’industrie française du terrassement est une histoire d’entrepreneurs venus à la profession à la faveur des programmes de grands travaux instaurés en France à partir de la monarchie de Juillet en 1830. Une nouvelle lignée d’entrepreneurs de la trempe de Georges Frot, d’Emile Razel en ou encore Firmin Deschiron, apparut. La construction de lignes ferroviaires en France leur avait offert un important débouché. Ce qui distinguait ces « hommes entreprises » de leurs pairs était dans de nombreux cas, la mise en place et la généralisation d’innovations techniques sur les chantiers dont ils avaient la charge. Les phases de reconstruction qui suivirent les deux conflits mondiaux, permirent à la profession de trouver un débouché dans les chantiers d’excavation et de déblaiement qui caractérisèrent ces périodes et, en particulier, après 1945, grâce à la mise en œuvre du Plan Marshall, lequel permit d’importants transferts de technologies américaines en matière d’engins de génie civil. Au cours des trente glorieuses, le lancement de programmes de grands travaux par les différents gouvernements de cette période continua de maintenir l’activité de la profession au dessus de la moyenne de celle de la branche toute entière des travaux publics. Les années 1980 et 1990 introduisirent l’industrie du terrassement toute entière dans une phase de regroupement et de reconfiguration dont témoigne encore aujourd’hui d’importants groupes de travaux publics comme le groupe Vinci. / The history of the French Industry of Earthworking is an history of entrepreneurs who came to the profession due to the major works program in France setting in place during the July Monarchy in 1830. A new lineage of some entrepreneurs such as Georges Frot, Emile Razel or Firmin Deschiron appeared. The construction of the railway network has given them an important outlet. What was identifying those “men companies” to their peers was, in numerous cases, the establishment and the Generalization of technical innovations on the Roadworks that they were having. The Reconstruction phases that followed the two World Wars enabled to the whole Industry of Earthworking to find an outlet with the different Roadworks of Excavation and clearance of this period, particularly, after 1945, thanks to the Marshall Plan, which enabled some important transfers of Americans technologies in terms of Earthworking machine; During the Thirty glorious, the launching of some politics of major Works by different governments in place continued to maintain the industrial activity to an high level compared with the entire branch of Publics Works. During the years 1980 and 1990, the Industry of Earthworking was introduced in an regrouping and reengineering phase. Some important groups of Publics Works like the Vinci group are still testifying of this change.

Municipalities are increasingly facing solid waste disposal problems due to lack of sanitary landfill sites, high costs of landfill management and increasingly stringent environmental standards. Consequently, they are turning toward innovative disposal practices to alleviate these problems. However, very little comprehensive information is available to decision makers on the range of options available in resource recovery development and the factors that can influence choices. This thesis tests the hypothesis that there are a definable set of factors or circumstances that have led resource recovery developers to make specific decisions regarding ownership, operation, financing, system technology, and air pollution control technology. The thesis is divided into three stages: development of case studies on 9 resource recovery facilities in the state of Virginia; development and analysis of a nationwide survey to test the patterns illustrated in these case studies; and finally, the development of a guide for resource recovery developers that will serve as preliminary guidance in their choice of development options. / M. Arch.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Expansive soils are a worldwide problem that possesses various challenges for civil engineers. With increasing water content, they exhibit excessive volume changes, resulting in large horizontal and vertical stresses to the structures located or buried in these regions. The most common method to minimize this effect is to replace these types of clays around the proposed structure with nonexpansive soils. For the cases needing larger volume of replacement, either sidewalls or the foundations must be designed to cater for the anticipated pressures or a suitable improvement technique shall be applied in place. In this experimental study, it is intended to investigate the possible positive effects of trenches backfilled with granular material such as crushed stone or rock on the improvement of swell parameters of expansive soils. Thin-wall oedometer tests, conventional oedometer tests and larger size tests with moulds were performed on artificially compacted untreated and granular fill treated samples for this purpose. The trenches were modeled by opening a hole with a diameter that satisfies the predicted percent trench content at the center of the soil samples, which was then backfilled with granular material. Modified thin-wall oedometer tests were performed to measure the lateral swell pressures of both untreated and treated samples, whereas the conventional oedometer tests and tests on samples placed in moulds were performed to measure the vertical swell parameters of soils. It was observed that both the vertical swell percentages as well as the lateral swell pressures reduced considerably as the volume of granular material filled trench was increased. The treatment was observed to be more remarkable under the surcharge effect of a light weight structure or a fill placed on top.

A numerical study was performed in order to investigate the effects of base excitation characteristics (peak acceleration amplitude and frequency of the excitation), soil strength and wall flexibility on the dynamic response of cantilever earth-retaining walls. In this study, Plaxis v8.2 dynamic finite element code was used. Previous 1-g shake table tests performed by &Ccedil / ali&amp / #56256 / &amp / #56570 / an (1999) and Yunat&ccedil / i (2003) were used to compare the experimental results with those obtained by finite element analysis. Comparison of experimental and numerical results indicated that the code was capable of predicting the dynamic lateral thrust values and bending moment profiles on the wall stems. In the light of these validation studies, a parametric study was carried on for a configuration that consists of an 8 meters high retaining wall supporting the same height of dry cohesionless backfill. Total and incremental dynamic thrust values, points of application and dimensionless bending moment values were presented together with the results obtained from commonly used pseudo static Mononobe-Okabe method and Steedman-Zeng approaches. According to the finite element analyses results, total dynamic active thrust act at approximately 0.30H above wall base. Base motion frequency becomes an important factor on magnitudes of dynamic active thrust when it approaches to the natural frequency of the system. Significantly high overturning moments were predicted at wall base in this case. It was observed that increasing wall rigidity causes an increase in forces acting on the wall stem during dynamic motion.

This study uses a 3D finite element program, calibrated with the results of a full scale instrumented load test on a limited size footing, to estimate the settlement improvement factor for footings resting on rammed aggregate pier groups. A simplified 3D finite element model (Composite Soil Model) was developed, which takes into account the increase of stiffness around the piers during the ramming process. Design charts for settlement improvement factors of square footings of different sizes (B = 2.4m to 4.8m) resting on aggregate pier groups of different area ratios (AR = 0.087 to 0.349), pier moduli (Ecolumn = 36MPa to 72MPa), and with various compressible clay layer strengths (cu = 20kPa to 60kPa) and thicknesses (L = 5m to 15m) were prepared using this calibrated 3D finite element model. It was found that, the settlement improvement factor increases as the area ratio, pier modulus and footing pressure increase. On the other hand, the settlement improvement factor is observed to decrease as the undrained shear strength and thickness of compressible clay and footing size increase. After using the model to study the behaviour of floating piers, it was concluded that, the advantage of using end bearing piers instead of floating piers for reducing settlements increases as the area ratio of piers increases, the elasticity modulus value of the piers increases, the thickness of the compressible clay layer decreases and the undrained shear strength of the compressible clay decreases.