The surface roughness of unfilled rock discontinuities has a major influence on the hydro-mechanical behaviour of discontinuous rock masses. Although it is widely recognized that surface roughness is comprised of large-scale (waviness) and small-scale (unevenness) components, most investigations of surface roughness have been restricted to small fracture surfaces (<1m2). Hence, the large-scale components of roughness are often neglected. Furthermore, these investigations typically define roughness using two-dimensional profiles rather than three-dimensional surfaces, which can lead to biased estimates of roughness. These limitations have led to some contradictory findings regarding roughness scale effects. This thesis aims to resolve some of these issues. The main findings indicate that discontinuity roughness increases as a function of the sampling window size contrary to what is commonly assumed. More importantly, it is shown that the estimated roughness significantly decreases as the resolution of surface measurements decrease, which could lead to the under estimations of roughness and, consequently, discontinuity shear strength.

Hydro One, a major distribution of electricity in Ontario, has reported that approximately 16,000 of the wood utility poles in its network of two million poles have been damaged by woodpeckers. With a cost of replacement of approximately $4000 per pole, replacing all affected poles is an expensive enterprise. Previous research conducted at UW attempted to quantify how different levels of woodpecker damage affected the pole strength. In the course of this research, some shear failures were observed. Utility poles being slender cantilevered structures, failures in shear are not expected. The objectives of this study were to determine the effective shear strength of wood utility poles and to determine the reliability of wood utility poles under different configurations, including poles that had been damaged by woodpeckers. An experimental programme was developed and conducted to determine the effective shear strength of wood poles. Red Pine wood pole stubs were used for this purpose. The stubs were slotted with two transverse half-depth cuts parallel to one another but with openings in opposite directions. A shear plane was formed between these two slots. The specimens were loaded longitudinally and the failure load was recorded and divided by the failure plane area to determine the shear strength. The moisture content of each specimen was recorded and used to normalize each data point to 12 % moisture content. The experimental study showed that the mean shear strength of the Red Pine specimens adjusted to 12 % moisture content was 2014 kPa (COV 47.5 %) when calculated using gross shear area, and 2113 kPa (COV 40.5 %) when calculated using net area. The shear strength of full-size pole specimens can be represented using a log-normal distribution with a scale parameter of λ = 0.5909 and a shape parameter of ζ = 0.5265. iii The reliability of Red Pine wood utility poles was determined analytically. A structural analysis model was developed using Visual Basic for Applications in Excel and used in conjunction with Monte Carlo simulation. Statistical distribution parameters for wind loads and ice accretion for the Thunder Bay, Ontario region were obtained from literature. Similarly, statistical data were obtained for the modulus of rupture and shear strength from previous research conducted at UW as well as the experimental programme conducted in this research. The effects of various properties on reliability were tested parametrically. Tested parameters included the height of poles above ground, construction grade, end- of-life criterion, and various levels of woodpecker damage. To evaluate the results of the analysis, the calculated reliability levels were compared to the annual reliability level of 98 % suggested in CAN/CSA-C22.3 No. 60826. Results of this reliability study showed that taller poles tend to have lower reliability than shorter ones, likely due to second-order effects having a greater influence on taller poles. The Construction Grade, a factor which dictates the load factors used during design, has a significant impact on the reliability of wood utility pole, with poles designed using Construction Grade 3 having a reliability level below the 98 % threshold. Poles designed based on Construction Grade 2 and 3 having reached the end-of-life criterion (60 % remaining strength) had reliability below this threshold whilst CG1-designed pole reliability remained above it. Wood poles with exploratory- and feeding-level woodpecker damage were found to have an acceptable level of reliability. Those with nesting-level damage had reliability below the suggested limits. Poles with feeding and nesting damage showed an increase in shear failure. The number of observed shear failure depended on the orientation of the damage. Woodpecker damage with the opening oriented with the neutral axis (i.e., the opening perpendicular to the direction of loading) produced a greater number of shear failure compared to woodpecker damage oriented with the extreme bending fibres.

Caribbean nations lie within a zone of distinct seismic hazard. While ground motion in the region has been analyzed, the potential for liquefaction has not been evaluated in most cases. In order to evaluate liquefaction, data describing soil composition, surficial geology, and seismic hazard analyses were collected and applied. This allowed for expansion of previously localized liquefaction analysis to be expanded to the extents of two island nations in the Caribbean. This thesis utilizes the Youd and Perkins (1978) qualitative liquefaction susceptibility and Holzer et al. (2011) liquefaction probability methodologies to evaluate the possibility of liquefaction in Trinidad and Jamaica during major seismic events. Maps were developed using geographic information system (GIS) data to compare susceptibility and hazard across the islands at varying levels of magnitude. In this way, the distribution of liquefiable deposits is displayed in a manner that can be used quickly and easily to motivate further study of susceptible regions and mitigation activities to reduce the risk posed by liquefaction in the countries.

Geomembranes are one of the most widely used geosynthetics in various civil engineering applications. Their primary function is as a barrier to liquid or vapour flow. Smooth Geomembranes are frequently used in combination with different soils, and due to their low surface roughness, are challenging to design to ensure adequate shear strength along the smooth geomembrane-soil interface. It is important to use the appropriate values of interface shear strength parameters in the design of slopes incorporating one or more geomembranes in contact with soils. The parameters are determined by conducting direct shear test on the geomembrane-soil interface. Laboratory tests of interface shear strength for geomembranes and soil are typically carried out with no provision for measurement of pore pressures at the soil/geomembrane interface. <p>This thesis deals with study of smooth geomembrane-soil interfaces, particularly under unsaturated conditions. The various factors that affect the interface shear behaviour are also studied. The tests were conducted using a modified direct shear box with a miniature pore pressure transducer installed adjacent to the surface of the geomembrane. Geomembranesoil interface shear tests were carried out with continuous measurement of suction in close proximity to the interface during the shearing process thus making it possible to analyze test results in terms of effective stresses. The method was found to be suitable for unsaturated soils at low values of matric suction. <p>Results of interface shear tests conducted using this method show that it is quite effective in evaluating interface shear behaviour between a geomembrane and an unsaturated soil. The results suggest that soil suction contributes to shearing resistance at low normal stress values. At lower normal stress values, the interface shear behaviour appears to be governed only by the magnitude of total normal stress. <p> At high normal stresses, the failure mechanism changed from soil particles sliding at the surface of geomembrane to soil particles getting embedded into the geomembrane and plowing trenches along the direction of shear. A plowing failure mechanism resulted in the mobilization of significantly higher shear strength at the geomembrane soil interface. It was found that placement water contents near saturated conditions results in lower effective stresses, a shallower plowing mechanism and lower values of mobilized interface shear strength.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Jeofizik Mühendisliği Anabilim Dalı, 2009. / Kaynakça var.

Mobile offshore drilling units are being used in the Gulf of Mexico to produce oil and gas. Anchoring systems such as drag embedment anchors and vertically loaded anchors are used to keep these units in place. Past mooring system failures due to hurricanes in 2004 and 2005 initiated a need to better understand the performance of these anchors to in-plane and out-of-plane loading conditions. In-plane and out-of-plane loading cause the anchor to translate or rotate in the directions of its six degrees of freedom. Behavior and holding capacity of the anchors when loaded in each of is six degrees of freedom are important in understanding and predicting their behavior. An experimental program was devised to investigate the behavior of anchors in pure translation and rotation loading. The scaled-model anchors were embedded at a measured depth in a soil bed of clay with an undrained shear strength between 10 and 20 psf and then loaded to failure. A rotation testing frame was designed to impose rotational loading in the yaw, roll and pitch directions. Test results from the experimental program are consistent and repeatable. The bearing factors for pure bearing fell well within the range of existing experimental and analytical studies on simple plates. Bearing factors for in-plane and out-of-plane shear and for all rotations are higher than those for simple plates due to presence of the shank. When the resistance is normalized by area of the fluke, the wider model provide greater normalized resistance to yawing, similar normalized resistance to pitching and rolling and less normalized resistance to bearing and shearing. It was concluded that the holding capacity of an anchor in its six degrees of freedom depends largely on its geometry, including the fluke and the shank. / text

Deep foundations, such as piles and suction caissons, are used throughout an offshore oil and gas production facility in deepwater. Ideally, the values of geotechnical properties for foundation design are determined by results from geotechnical investigation programs performed at the site of the foundation. However, the locations for facilities are not known exactly when soil borings are drilled and the footprint of a facility in deepwater can be very large with numerous foundation elements spread out over miles. Therefore, it is not generally feasible to perform a site-specific investigation for every foundation element. The objective of this research is to assess, analyze and model spatial variability in geotechnical properties for offshore foundations. A total of 97 geotechnical investigations from 14 offshore project sites covering the past twenty years of deepwater development in the Gulf of Mexico are compiled into a database. The geologic setting is primarily a normally to slightly overconsolidated marine clay, and the property of interest for the design of deep foundations is the undrained shear strength. The magnitude and characteristics of variability in design undrained shear strengths are analyzed quantitatively and graphically. Geostatistical models that describe spatial variability in the design shear strength properties to the distance away from the available information are developed and calibrated with available information from the database. Finally, a methodology is presented for incorporating the models into a reliability-based design framework to account for spatial variability in foundation capacity. Design examples are presented to demonstrate the use of the reliability methodology. Based on the design undrained shear strength profiles for the past 20 years in this Gulf of Mexico deepwater area, the design undrained shear strength varies spatially but does not depend on the time or method for site investigations. There are nonlinear spatial relationships in the point shear strength laterally and vertically due to stratigraphy such that depth-averaged shear strengths are correlated over further distances than point shear strengths. The depositional forces are an important factor causing spatial variations in the undrained shear strength, with greater variation and less spatial correlation in the more recent hemipelagic deposits (about upper 60 feet) than the deeper turbidite deposits and along the shelf versus off the shelf. The increased conservatism required in deep foundation design due to spatial variability when site specific strength data are not available is generally small with less than a five percent increase required in design capacity in this geologic setting. / text

Contaminated sites are found all around the world. In order to contain these contaminants, engineers propose capping the contaminated sediments with a sand cap. When capping these contaminants, the sand causes consolidation to occur and could cause a slope failure if the contaminants were on a slope. Investigating the properties of these contaminated sediments allows for proper analysis of a slope failure. The primary objective of this research was to determine the shear strength of contaminated sediments. Since soil samples from actual contaminated sites are highly variable and difficult to explain, the soil used in this research project was mixed and controlled in the lab. A mixture of Kaolinite, water and mineral oil (NAPL, non-aqueous phase liquid) was used for the specimens. Different oil amounts were placed into the specimens to create different scenarios. The different oil combinations included: 100% water, 100% oil, 90% oil, 70% oil, and 50% oil. All of the specimens were fully saturated, and the specimens that had less than 100% oil contained water in the remaining percentage. Consolidated Undrained and Consolidated Drained triaxial tests were performed on the specimens. The constructed specimens were subjected to consolidation stages ranging from 0.6psi to 29psi in confining pressure. The main focus of the study was on low confining pressures. After consolidation the specimens were sheared either undrained or drained. Both tests were utilized in order to see the difference in the pore pressures generated. Failure envelopes were developed for the different oil contents that contained three dimensions included the shear strength, the effective stress, and the pore pressure difference between the pore oil pressures and the pore water pressures. Also, the behavior of oil-dominated versus water-dominated was determined. Results from the 100% water specimens were comparable to previous data. The shear strength for the 100% oil specimens was higher than the 100% water specimens, but lower than the 90% oil and 70% oil specimens. The 50% oil specimens resulted in a great deal of variability on whether the specimen was water-dominated or oil-dominated. The main conclusion was that the Kaolinite had an increase in strength with the introduction of mineral oil. / text

published_or_final_version / abstract / toc / Civil Engineering / Doctoral / Doctor of Philosophy

Στην εργασία αυτή αρχικά πραγματοποιείται μια σύντομη περιγραφή της γεωλογίας του νομού Αχαΐας με παράθεση στοιχείων της σεισμικότητάς της ευρύτερης περιοχής καθώς και παράθεση υδρομετεωρολογικών στοιχείων. Η σπουδαιότητα των στοιχείων αυτών έγκειται στην κατανόηση του ευρύτερου γεωλογικού περιβάλλοντος στο οποίο ανήκουν και οι σχηματισμοί των οποίων οι ιδιότητες διερευνήθηκαν. Ακολουθεί η περιγραφή των εργαστηριακών δοκιμών που εκτελέστηκαν, σύμφωνα με τις προδιαγραφές της ισχύουσας νομοθεσίας αλλά και της διεθνούς πρακτικής. Στη συνέχεια σχολιάζονται θέματα σχετικά με την δειγματοληψία και την περιγραφή των γεωλογικών σχηματισμών που απασχολούν την εργασία αυτή. Παρουσιάζονται αναλυτικά ο τρόπος και οι θέσεις λήψεως δειγμάτων, ενώ παρέχονται και στοιχεία από τη γεωλογία της εκάστοτε περιοχής σε μια προσπάθεια να συγκεντρωθούν κατά το δυνατόν περισσότερα δεδομένα που συσχετίζονται με τους εδαφικούς σχηματισμούς που μελετήθηκαν. Δίνονται, τέλος, τα αποτελέσματα των εργαστηριακών δοκιμών και παρουσιάζονται τα συμπεράσματα που προέκυψαν, ενώ παρατίθενται και τα πλήρη στοιχεία που αφορούν στην εκτέλεσή τους. Στα πλαίσια του στόχου της πλήρους ανάλυσης και της απόδοσης μιας ολοκληρωμένης εικόνας των σχηματισμών, εκτελέστηκαν, πλέον των εργαστηριακών δοκιμών προσδιορισμού των παραμέτρων διατμητικής αντοχής και δοκιμές προσδιορισμού των αντίστοιχων παραμέτρων που σχετίζονται με τις φυσικές τους ιδιότητες. Με τα στοιχεία που προέκυψαν έγινε μια απόπειρα συσχετισμού των μεγεθών μεταξύ τους, ώστε να διαφανούν πιθανές εξαρτήσεις και να εξηγηθούν διαφοροποιήσεις στα αποτελέσματα των δοκιμών. / In this essay there is initially presented a short description of the geology of prefecture Achaia with apposition of data of it’s wider region seismicity as well as apposition of hydrometeorological data. The importance of presenting this data lies in the comprehension of the wider geological environment in which the formations of this work’s interest belong. Then there follows the description of laboratorial tests that were executed, according to the specifications as presented in effect legislation but also set by international practice. There are also presented subjects with regard to the sampling methods and the description of geological formations that occupy this work’s area of interest. There are analytically presented the way and the sites of reception of samples, while there is also analyzed information regarding to the geology of each site in order to collect as much data connected to the soils that were studied as possible. There are finally presented the results of laboratorial tests (and also the conclusions that resulted). In the objective of complete analysis and the understanding of the marl-type soils that were investigated, along with the elements that resulted, there was an attempt of correlation between shear strength parameters and soil properties, so that should emerge likely dependences and would be explained differentiations in the results of laboratory testing.