Дисертації з теми "WEAK SOIL"

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 163-170). Also available in electronic version. Access restricted to campus users.

Some soils set to a hard structureless mass on drying and this behaviour may limit crop productivity. The purpose of this study was to assess the extent to which soil management and soil properties influence hard-setting behaviour in order to identify those soil properties which are most appropriate to characterise the limitations to management and crop growth imposed by hard-setting. Five sites from four vegetation zones of Nigeria were investigated. Within each site soils were sampled from no-till or forested plots and these were contrasted with cleared (deforested) amd ploughed plots. Hard-setting behaviour was determined by measuring the unconfined compressive and tensile strengths of small undisturbed cores (minicores) which had been equilibrated at a range of matric potentials. Rooting potential was assessed both by measuring needle penetrometer resistance or cores equilibrated at potentials of -6 and -100 kPa; and also by measuring penetrometer resistance in the field at a range of moisture contents. Soil bulk density, organic matter concentration, soil friability, aggregate stability and amounts of water suspendable solids were also measured to assess soil properties that are likely to be diagnostic of hard-setting behaviour. The limitations imposed by hard-setting behaviour on rooting and yields of maize and cowpea were assessed at IITA. The minicore strengths increased as the moisture content decreased but the increase was much more marked for mechanized cleared or tilled soils than for the less disturbed treatments of forestry and a no-till system. For all soils the most pronounced effects of moisture content deplection on soil strength occurred at potentials of < -100 kPa. Theoretical considerations indicated that the effective stress accounted for over half of the strength of minicores at -100 kPa and more than accounted for the strength of minicores at -1 MPa. The greater strength in tilled soils was attributed to a decrease in organic matter content, wet aggregate stability and friability and to an increase in bulk density. Needle and field penetrometer resistance results indicated that rooting potential was reduced on hard-setting soils and actual root measurements supported this view. Consequently maize and cowpea yields were reduced.

The aim of this study was to improve the characteristics of surfacing methods/materials for the temporary support of military vehicles travelling over weak soils. Both off road travel and poor existing road networks provide problems for vehicle mobility in military operations under these conditions. Conventional road construction materials are often in short supply and engineered solutions such as Class 30 & 70 Trackway are expensive and form a significant logistical burden on the military supply chain. In this situation the use of locally available alternative materials in the construction of temporary roads can reduce the time taken to get routes operational, allowing the tempo of operations to be maintained. The work reported focussed on two main areas of work, namely: i) The development of a technique for assessing the soil support capacity in the form of a flat plate (45 x 30 mm) penetrometer to aid the decision/ planning process when faced with poor soil support, and ii) the evaluation of the relative performance of a range of alternative materials/ techniques in laboratory conditions at 1/5'*’ scale and full size. The results of load-sinkage tests of a family of plate sizes indicate that by normalising the data with respect to plate width a common relationship existed for all plate sizes in each of the soil conditions investigated. From this, a technique was developed to estimate the load support of a plate with dimensions equivalent to the contact patch of a tyre using load-sinkage data from a small plate penetrometer, allowing estimates of: i) sinkage or rut depth expected from a vehicle load, and ii) the load at a sinkage equivalent to the tyre contact patch width, a point at which the vehicles were assumed to be immobilised. Comparison between the rut depth of a single pass of a towed wheel and the sinkage from plate tests (45 x 30 mm) were within 20% in a sandy loam soil of bulk unit weight 12.2 and 13.4 kN/m^. Load sinkage predictions of a 450 x 300 mm plate from a small plate penetrometer were within 35% in a sandy loam soil with bulk unit weights of 11.7 and 13.4 kN/m^. Load sinkage predictions for a very weak sandy loam (11.3 kN/m^) and loose sand (15.1 - 16.1 kN/m^) soils tended to be significantly underestimated especially at large plate sizes, mainly due to scaling effects in these David Shorten, 2004 Cranfield University, Silsoe 11 situations as well as the significant re-arranging occurring in weak soil subjected to loaded plates. Improvements in accuracy to 25-35% could be made in these conditions by increasing the size of the plate penetrometer to 90 x 60 mm and utilising a similitude scaling technique. Materials/techniques for improving soil support have been classified into 4 categories, namely: sheet materials, rigid members, aggregate materials and stabilisation techniques. The use of sheet materials, in this case a Hessian geotextile, proved effective in improving the in situ soil support; it was possible to optimise the width and placement depth to increase load support by a factor of 1.8. A folded confinement technique encapsulating a soil fill was developed further, resulting in a 3-fold improvement in the load support. Tied corduroy techniques performed best with a 5- fold improvement in load support. Factors such as the rope tension between members were found to be important to produce a stable road surface. The performance of aggregates increased with larger aggregate sizes. Increasing the thickness of the aggregate layer enhanced load support in stone aggregate, while in wood and rubber aggregate performance is affected by the initial compressibility of the material. Aggregate mixed with a sand filler proved effective at reducing the compressibility of the alternative aggregate materials, thus enhancing performance. The use of alternative materials in military operations has been identified as very scenario dependent. Alternative materials have been shown to increase the load support capability of weak soils. Although alternative materials are unlikely to be used as a substitute in conventional road construction, their use on short sections of roadway is feasible. Situations where conventional aggregate materials are limited and an alternative aggregate can be obtained locally would offer a solution enabling military operations to continue. Significant quantities of materials are required to construct even small sections of roadway in weak soil conditions; success is very much dependent on the amount of material locally available, for example a 100 m section may require 180 m^ of timber aggregate approximately equal to 0.25 ha of a 45 yr Sitka Spruce plantation. This information will be of use to aid decisions made by the Combat Engineer and has been recommended by the MOD for inclusion in the Military Engineering Volume.

Geokunststoffe sind beständige Produkte aus Polymeren, die in Boden eingelegt werden um geotechnische Probleme zu lösen. Eine Kategorie der Geokunststoffe sind Geogitter, bei denen die Längs- und Querelemente eine offene, gitterförmige Struktur bilden und die meist zur Bodenbewehrung eingesetzt werden. Ihre Verwendung zur Bewehrung von gering tragfähigen Böden für kunststoffbewehrte Erd- und Stützbauwerke kann enorme ökologische und ökonomische Vorteile bieten. Trotz der Tatsache, dass die Verwendung von Geogittern in den letzten Jahren stark zugenommen hat, sind die Grundlagen zum Bau und zur Bemessung limitiert. Besonders die Schlüsselfrage, wie Geogitter und verschiedene Lockergesteine in unterschiedlichen Belastungssituationen interagieren, ist ingenieursmäßig nur lückenhaft untersucht worden. Im Rahmen dieser Dissertation wurde deshalb in über 250 großmaßstäblichen Scher-, Herauszieh- und Reibungsversuchen das Verbundverhalten Geokunststoff/Locker¬gestein eingehend untersucht. Dazu wurden 14 handelsübliche Geogitter, die teilweise auch modifiziert wurden, in dem Interaktionsprüfgerät des Institutes für Geotechnik der TU Bergakademie Freiberg mit verschiedenen Böden systematisch getestet. Die vielen Versuchsanordnungen und die aus ihnen abgeleiteten Überlegungen und gewonnenen Erkenntnisse belegten, dass die wichtigsten Parameter interagieren, und zwar in verschiedenen Abhängigkeiten wie weitere Variationen der Bodenparameter (Kornverteilung, Wassergehalte, Verdichtung, Bindemittelzusatz etc.), der unterschiedlichen Geogitterparameter (Oberflächenbeschaffenheit, Struktur, etc.) und der Belastung gezeigt haben. Darüber hinaus wurde das Interaktionsprüfgerät für zukünftige Versuche weiterentwickelt (Entkopplung des Versuchseinbaus vom Versuchsgerät usw.). Der Fokus der Forschungsarbeit lag dabei in der Schaffung von Grundlagenkenntnissen für den gemeinsamen Einsatz von bindigen Lockergesteinen und Geokunststoffen. Bei rolligen Böden zeigte sich, dass die Rautiefe sich stärker (positiv) auf die Widerstände auswirkt als bei den bindigen Böden. Hingegen waren bei bindigen Böden die Auswirkungen durch eine Erhöhung der Querelemente deutlicher. Darüber hinaus konnte gezeigt werden, dass dreidimensionale Querelemente das Verbundverhalten verbessern und Tests an Geogittern mit einem größeren Verhältnis von Öffnungsweite zu Maschenweite zeigten höhere Adhäsionswerte. Die Reibungsversuche hatten einen gleichmäßigeren Verlauf und geringere Streuungen zwischen den unterschiedlichen Geogittern, weshalb aufgrund der deutlicheren Unterschiede zwischen den Produkten bei den Herausziehversuchen detaillierte Schlussfolgerungen gezogen werden konnten. Die vorliegende Arbeit leistet einen Beitrag zur Verbesserung der Bemessungsgrundlagen und ermöglicht ein detaillierteres Verständnis des Verbundverhaltens. Des Weiteren werden Vorschläge ausgearbeitet die im Labor erzielten Ergebnisse auf die Baupraxis zu übertragen, wie zum Beispiel durch das Vermeiden von Trennflächen zwischen Geogitter und Boden bei der Verdichtung
Geosynthetics are durable polymeric products placed in soil to help solve civil engi-neering problems; one category of these is geogrids. Geogrids are polymers formed into an open, grid-like configuration and function primarily as soil reinforcement. Their use to reinforce soil with weak bearing capacity could have big ecological and economical advantages. Although geogrid use has grown in recent years, there is still limited design information available due to the wide variety of design configurations and soil variability. One of the key factors lacking for more widespread engineering implementation is a greater understanding of the interaction between various geogrids and soil combinations when exposed to different load effects. In more than 250 shear, pull-out, and friction tests, this interaction behavior was examined in detail. Fourteen general geogrids (sometimes additionally modified) using dif-ferent soil types were systematically tested in the Interaction Testing Device at the Geotechnical Institute of the TU Bergakademie Freiberg. Combining the huge quantity of test results with a theoretical analysis, the main parameters which affect soil behavior could be defined. Furthermore the Interaction Testing Device could be improved for test in future. Our analysis showed us that the roughness of the geogrid has more of a beneficial impact on the strength of frictional soils than it does for silty soils. Silty soils however, were more affected by the height of cross elements in the geogrid than other types. It was also observed that 3D elements in the cross machine direction improve the interaction behavior. Tests with geogrids which have a bigger ratio of opening size to mesh size showed higher adhesion values. The friction test results were more regular, had a uniform progress and had smaller differences between geogrid configurations. Therefore, conclusions with higher certainty could be drawn from the pull-out tests with the differential results. The present research contributes to the limited design information to help provide a better understanding of the interaction behavior. Furthermore, suggestions are given to use the laboratory detected results in real-world applications, one of which is the way of compaction to minimize the potential for creating a slip-surface between the geogrid and soil

Розглянуто основні конструктивні схеми фундаментів для малоповерхового будівництва при великій товщі глинистого ґрунту. Виконано розрахунок і проектування обраних конкурентоспроможних варіантів фундаментів, техніко-економічне порівнянні конструктивних рішень і вибір найбільш оптимального з них.
The basic constructive schemes of foundations for low-rise construction with a large thickness of clay soil are considered. The сalculation and design of selected competitive options, technical and economic comparison of constructive solutions and the choice of the most optimal ones are performed.

Bibliography: pages 133-136.
A survey has been made of the quality and type of materials used for tillage tools in South Africa. Conclusions have been drawn regarding the inadequacy of the manufacturing processes used and the resultant quality of the tool material. A rig has been designed for the abrasion testing of materials in soil. The reproducibility of the method has been shown to be high and an evaluation has been made of the relative wear resistance of a series of ·heat treated steels. A medium carbon boron steel has been shown to have great promise as a tillage tool material because of its high wear resistance and toughness. The deformed surface layers and the mechanisms of wear of steels subjected to field and laboratory abrasive testing has been examined. The removal of material through predominantly ploughing or cutting mechanisms has been shown to be dependent on the heat treatment and composition of the steels together with the nature of the abrasive. White surface layers have been observed to form on medium and high carbon steels subjected to soil abrasion. Suggestions have been advanced for their formation. Attempts have been made to assess the transferability of data between field and laboratory testing.

Materiales arcillosos rígidos, que se encuentran en la zona de transición entre suelos duros y rocas blandas, están siendo considerados actualmente en varios países como la roca huésped para el almacenamiento geológico profundo de residuos nucleares de alta actividad y larga vida. Esta posibilidad a derivado en la construcción de laboratorios de investigación subterráneos (LIS), excavados en estos materiales arcillosos rígidos, para estudiar su comportamiento bajo condiciones reales de trabajo. Entre los diferentes aspectos estudiados en los LIS, el comportamiento hidromecánico de la roca huésped es el más relevante para la presente investigación. Observaciones in situ han revelado que las excavaciones inducen daño alrededor de los túneles, en la forma de redes de fracturas, contenidas dentro de una zona llamada la zona de daño de la excavación (ZDE). La ZDE se ha identificado como una de las principales causas afectando el comportamiento de las excavaciones. En este contexto, el principal objetivo de la presente investigación es la simulación numérica del comportamiento hidromecánico de excavaciones experimentales llevadas a cabo en el LIS Meuse/Haute-Marne (Francia). Para lograrlo, se desarrolló un modelo constitutivo para caracterizar la roca huésped. El modelado de estos materiales es una tarea desafiante. Estos materiales exhiben características más propias de los suelos como considerables deformaciones plásticas, dependencia con la velocidad de carga, y creep, aunque también muestran características más típicas de las rocas como un considerable reblandecimiento y deformaciones plásticas localizadas. Además, debido a su origen sedimentario, también exhiben anisotropía en propiedades como su rigidez, resistencia, y permeabilidad. Se prestó especial atención a la reproducción de la ZDE y, por lo tanto, a la simulación objetiva de deformaciones localizadas; se empleó un enfoque no local para la regularización del continuo, el cual evita la dependencia con la malla empleada. Los resultados obtenidos proporcionan importantes conclusiones respecto al comportamiento hidromecánico de estos materiales arcillosos rígidos, e indican los principales aspectos que afectan la respuesta de las excavaciones subterráneas. En particular, se demuestra la importancia de la ZDE.
Stiff clayey materials, lying in the transition between hard soils and weak rocks, are being currently considered in several countries as possible host medium for deep geological disposal of high active and long-lived nuclear waste. This possibility has led to the construction of underground research laboratories (URL), excavated in these indurated clayey materials, to study their behaviour under real working conditions. Among the very different topics addressed in the URLs, the hydromechanical behaviour of the host rock is the one that most concerns the present research. In situ observations have revealed that excavation operations induce damage around the galleries, in the form of fracture networks, contained within a zone called excavation damaged zone (EDZ). The EDZ has been identified as one of the main aspects affecting the behaviour of the excavations. In this context, the main objective of the present study is the numerical simulation of the hydromechanical behaviour of experimental excavations performed at the Meuse/Haute-Marne URL (France). For this purpose, a constitutive model has been developed to characterise the host formation. The modelling of these stiff argillaceous materials is a quite challenging task. They exhibit soil-like features like considerable plastic strains, rate-dependency, and creep, although they also show characteristics more typical of a rock such as significant softening and localised deformations. In addition, due to their sedimentary origin, they often exhibit anisotropy in properties like stiffness, strength, and permeability. Special attention has been paid to the reproduction of the EDZ and, therefore, to the objective simulation of localised deformations; a nonlocal approach has been employed for the regularisation of the continuum, avoiding the dependence on the employed mesh. The obtained results provide relevant insights into the hydromechanical behaviour of these stiff clayey materials, and they indicate the main aspects affecting the response of the underground excavations. In particular, the relevance of the EDZ has been demonstrated.

UA : В дисертації наводяться результати досліджень для вирішення актуальної нау- ково-практичної задачі підвищення ефективності підсилення основ споруд при від- новленні деформованих будівель та при реконструкції будівельних об’єктів шляхом розробки технології горизонтального бурозмішувального армування ґрунтів із за- стосуванням розроблених інноваційних конструктивно-технологічних рішень. В роботі визначені шляхи підвищення ефективності відновлення пошкодже- них будівель внаслідок: покращення якості формування ґрунтоцементних армоеле- ментів внаслідок зміни технологічних процесів бурозмішування; зниження трудомі- сткості та підвищення технологічності виконання робіт розробленням та удоскона- ленням конструктивно-технологічного обладнання та оснащення; забезпечення без- перебійної експлуатації будівельних об’єктів та без відселення людей на період від- новлювальних робіт; можливості виконання відновлювальних робіт в стиснених умовах. Представлені результати дослідження впливу технологічних факторів на про- цес утворення в ґрунтовій товщі горизонтальних ґрунтоцементних армоелементів та отримані залежності такого впливу на формування механічних характеристик ґрун- тоцементу, які дозволяють встановлювати раціональні технологічні режими арму- вання ґрунтів в залежності від їх фізичного стану. Впровадження результатів дисертаційної роботи відбулося при стабілізації деформацій споруди виниклих в процесі будівництва, при відновленні експлуата- ційної спроможності деформованої будівлі навчально-виховного комплексу та при реконструкції із надбудовою поверху будівлі готелю.
RU : В диссертации приводятся результаты исследований для решения актуальной научно-практической задачи повышения эффективности усиления оснований со- оружений при восстановлении деформированных зданий и при реконструкции стро- ительных объектов путем разработки технологии горизонтального буросмеситель- ного армирования грунтов с применением разработанных инновационных конструк- тивно-технологических решений. В работе определены пути повышения эффективности восстановления повре- жденных зданий за счет: улучшения качества формирования грунтоцементных ар- моэлементов вследствие изменения технологических процессов буросмешивания; снижения трудоемкости и повышения технологичности выполнения работ разработ- кой и усовершенствованием конструктивно-технологического оборудования и оснастки; обеспечения бесперебойной эксплуатации строительных объектов и без отселения людей на период восстановительных работ; возможности выполнения восстановительных работ в стесненных условиях. Подтверждена гипотеза о том, что в результате использования разработанных инновационных конструктивно-технологических решений, а именно – трёхлопаст- ного буросмесителя и горизонтального бурового станка, оснащённого трёхскорост- ными редукторами линейного и вращательного движений приводит к изменению принципа буросмесительных процессов (разрушения структуры грунта, измельче- ния разрушенного грунта, пропитывания измельчённого грунта водоцементной сус- пензией, перемешивания грунтоцементной смеси), что обеспечивает многократную обработку каждого элементарного объёма укрепляемого грунта указанными буро- смесительными технологическими операциями. Поскольку буросмесительная технология основана на разрушении структуры грунта и пропитывании разрушенного грунта водоцементной суспензией, в работе исследован процесс резания грунта новой конструкцией буросмесителя и установ- лено влияние технологических параметров на этот процесс. С учётом разработанных конструктивно-технологических решений горизон- тального буросмесительного армирования грунтов выполнены полевые исследова- ния технологических процессов устройства горизонтальных грунтоцементных армо- элементов и влияния технологических факторов на формирование механических ха- рактеристик. При этом проверена возможность обеспечения горизонтальности и па- раллельности смежных армоэлементов разработанной на уровне изобретений техно- логической оснасткой. Выполненные исследования разработанной технологии пока- зали положительные результаты При проектировании усиления оснований укреплением грунтов буросмеси- тельным армированием технологии возникают вопросы связанные с механическими характеристиками. Поэтому выполнены исследования влияния технологических па- раметров на изменение свойств грунтоцемента неразрушающими методами – пене- трацией и ударно-импульсным методом, а также испытанием образцов на одноосное сжатие. По результатам испытаний установлены зависимости изменения характери- стик удельного сдвига, поверхностной твёрдости и призменной прочности грунто- цемента при изменении технологических параметров.
EN : The dissertation provides the results of research for solution of important scientific and practical problem of increase of efficiency of buildings bases in the reduction of deformed buildings and renovation construction projects through the development of technology of horizontal soil-and-mixing reinforcement using developed innovative structural and technological solutions. The ways of increasing the efficiency of restoration of damaged buildings are determined at the expense of: improvement of the quality of formation of ground-cement armoelements due to changes in the technological processes of drilling-mixing; Reduce labor intensity and improve the technological work performance by developing and improving the design and technological equipment and equipment; Maintenance of uninterrupted operation of building objects and without resettlement of people for the period of restoration works; The possibility of carrying out restoration work in cramped conditions. The results of a study of the influence of technological factors on the process of the device in the soil thickness of horizontal soil-cement elements are presented, and the dependence of such influence on the formation of mechanical characteristics of soil cement is obtained, which allow to establish optimal technological regimes of reinforcement of soils depending on their physical state. The introduction of the results of the thesis work occurred with the stabilization of the deformations of the structures that emerged during the construction process, while restoring the operational fitness of the deformed building of the educational complex and during the reconstruction with the building's superstructure.

Soil engaging tools are subjected to durability problems due to particularly severe wear. During ploughing work wear is generated by the interaction between tillage tool and soil. There are several wear modes on tillage tools, but the predominant cause of material loss is due to the abrasive action of soil particles. Wear rate is strongly affected by soil-tool pressure distribution and it compromises plough performances during its life cycle. The aim of this PhD thesis is the development of a test methodology able to measure and evaluate the pressure distribution on a working plough body using tactile sensors. Field tests were performed with a 4 furrows reversible plough by Gruppo Nardi attached to a New Holland T7.260 tractor and tested at different soils, speeds and ploughing depths. Tractor speed and the horizontal force at the hitch points of the plough were measured. The pressure mean value is influenced both by speed and depth, but each part of the plough has its own characteristic behaviour. The pressure signals demonstrated to be spiky, in fact the pressure mean value was lower than 1% of the maximum value for up to 92% of the ploughed distance. Moreover, spike patterns are markedly affected by the speed especially in terms of the number of spikes and their distribution. The methodology and the results introduced in this PhD thesis will be useful for the validation of mathematical models to simulate the ploughing process, reducing the time required for the engineering design process of optimized ploughs. A possible future development of this research activity is the design of accelerated tests in order to permit a fast validation of plough bodies.

Bibliography: pages 96-104.
A hypoeutectoid steel has been heat treated to produce a range of different hardnesses and microstructures. A simulative field test rig has been employed to determine the relationship between microstructural parameters, material properties and soil constitution. Attempts have been made to correlate the ranking order for the wear resistance of similar treated steels in field and laboratory tests. It has been established that wear resistance is a function of soil constitution, steel carbide morphology and hardness. Explanations have been advanced for the differences in the wear resistance of similar steels in different soils based on the mechanism of material removal. Recommendations have been made regarding the selection of steel microstructure for varying soil conditions.

Underground construction in urban areas that need more efficient transportation systems, energy and water supplies is a very challenging task, due to the complexity of the work itself and because surface disturbances and subsidences require to be minimized. In order to face the challenge and allow the excavation of tunnels even with low overburdens, Earth Pressure Balance Shields (EPBS) technology has been increasingly used in the recent years. EPBS is a type of tunnel boring machine (TBM) with earth pressure support. By transforming the excavated material into a soft paste that has plastic properties to be used as support medium, it is possible to balance the pressure conditions at the tunnel face allowing minimum settlement. In addition, uncontrolled inflow of soil and water into the machine is avoided and tunnelling process becomes more effective. In order to better understand soil behaviour and improve the performance of the EPBS machine, two variables are studied: soil conditioning and tools wear. During excavation with EPB machines the correct soil conditioning is a very important parameter to be controlled. For this reason, it is critical to perform preliminary tests with different conditioning agents in order to determine the most suitable reference dosage for an excavation project. Currently, soil conditioning is evaluated by performing slump tests and plasticity and homogeneity checks of the dough at laboratory scale. There is also the Extraction Test used to evaluate material extraction that is one of the most realistic tests to know the behaviour that soil could develop during excavation process. On the other hand, a very important but still less studied variable is the wear of EPBS metal parts like excavation tools, rotating head, shield and screw conveyor. Wear leads to a reduction in working yield due to the mentioned machine components lose their optimum properties and have to be replaced; consequently, downtime is required in order to execute proper maintenance, which is difficult and dangerous. Many aspects play key roles in the wear process like excavated medium, water content, applied pressure, soil conditioning and type of metal used for machine tools manufacturing. In fact, rocks and soil excavated during EPB work can be composed from any kind of minerals. Hard minerals increase the wear phenomenon that concerns all parts of the machine where there is friction between metallic part and the medium. For this reason, study of wear phenomenon is an extremely important issue for new projects with EPB excavation technology. Therefore, the objective of this work is to study of the influence of soil conditioning on tools wear and the relationship of the main factors associated to this phenomenon. In order to accomplish this goal, about 26150 kg of different soils were studied using 4 different wear test methods. These tests were based on the application of a test methodology already used in the Tunnels and Underground Works Laboratory of Politecnico di Torino and other new methodologies and equipment, developed with the aim of deepening the study of wear taking into account several variables that concern the construction of tunnels. Each methodology implemented has different benefits, limitations and scopes, but provides congruent technical results. Finally, prediction indexes were proposed in order to evaluate tool wear phenomenon and compare the effects of different soil conditioning. As a result, better decisions are made when choosing the ideal conditioning for EPB tunnelling, maximizing projects effectiveness and success.

Cette étude porte principalement sur l’évaluation d’estimations de précipitations par satellite à haute résolution pour l’hydrologie du bassin central de lacs de la vallée du Rift en Éthiopie. La première partie est consacrée à la correction du biais de pluie par satellite pour la simulation du débit et du bilan hydrique au niveau des lacs. Ensuite, l'impact du captage d'eau et d'autres facteurs sur le bilan hydrique du lac, en particulier sur le niveau et la variation du volume de l'eau, sera étudié. Enfin, l’étude quantifiera les demandes actuelles et futures et évaluera ainsi l’impact de différents scénarios de développement des ressources en eau sur le bilan hydrique du lac. Dans cette étude, nous avons évalué la performance et la correction de biais du satellite CHIRP (Satellite Hazards Group) pour la simulation pluie-ruissellement. Nous avons également évalué les effets des paramètres et des performances du modèle calibrés à la suite de différentes entrées de précipitations. Nous avons appliqué une méthode de puissance non linéaire pour corriger le biais de la CHIRP dans la simulation du débit des bassins versants de Meki et Katar à l'aide du modèle Hydrologiska Byråns Vattenbalansavdelning (HBV). Ensuite, un ensemble de données de précipitations corrigées de biais a été simulé dans une modélisation pluie-ruissellement, où l'écoulement simulé a été utilisé pour la simulation du niveau d'eau du lac Ziway dans le modèle de bilan hydrique du lac. Ensuite, nous avons mené une enquête sur les prélèvements d'eau (WAS) afin d'estimer les prélèvements d'eau réels dans le lac et un modèle de bilan hydrologique pour évaluer l'impact isolé des prélèvements d'eau sur le volume et le niveau de l'eau du lac. L'impact probable de trois voies de développement sur le stockage du lac et le niveau de l'eau a été évalué. L'étude a également appliqué un modèle d'évaluation et de planification de l'eau (WEAP) pour évaluer la demande en eau existante et future afin d'évaluer l'impact du développement des ressources en eau sur le lac, sur le niveau et le volume de l'eau du lac. Dans les simulations, le bassin versant est divisé en différents sous-bassins principaux où les nœuds de l'offre et de la demande sont localisés dans l'espace et modélisés. Les secteurs de l’eau en concurrence sont le développement de l’irrigation, les utilisateurs domestiques et les besoins en matière de débits environnementaux identifiés pour l’abstraction. En conséquence, à partir des résultats de la simulation, le captage annuel moyen total du volume d’afflux et de la disponibilité en eau sera évalué en fonction de la couverture de la demande et de la fiabilité. Ainsi, l’étude identifiera les facteurs possibles d’attribution du bilan hydrique du lac et fournira des informations aux décideurs, aux planificateurs et aux utilisateurs d’eau pour une meilleure gestion des prélèvements d’eau du lac
Des changements importants ont été observés dans le bilan hydrique du bassin des lacs de la vallée centrale du Rift (CRV) en Éthiopie au cours des dernières décennies, ce qui entrave leurs services pour une grande variété d'écosystèmes. Cependant, les contributions des composantes du bilan hydrique n'ont pas encore été quantifiées en raison du manque de disponibilité continue des données et de réseaux de pluviomètres suffisants. Dans cette étude, nous avons utilisé l'estimation des précipitations par satellite du groupe Climate Hazards Group InfraRed Precipitation (CHIRP) en utilisant la modélisation des précipitations et du ruissellement où le ruissellement simulé a servi d'entrée à la simulation du niveau de l'eau. La thèse se compose de quatre étapes ultérieures. Les deux premiers se concentrent sur l'évaluation et la correction des biais des précipitations du satellite CHIRP pour simuler le débit et le niveau de l'eau du lac en utilisant le modèle Hydrologiska Byråns Vattenbalansavdelning (HBV). Le troisième se concentre sur la quantification du prélèvement d'eau réel et de son impact sur le bilan hydrique du lac à partir des données des relevés de captage d'eau. Dans la dernière étape, nous avons évalué la demande d'eau actuelle et future à l'aide du modèle d'évaluation et de planification de l'eau (WEAP) et évalué les impacts probables du développement des ressources en eau sur le niveau d'eau des lacs CRV. Les résultats montrent que CHIRP a des biais à différentes échelles spatiales et temporelles. Cependant, la correction du biais de l'estimation satellite a considérablement réduit le biais et a révélé de meilleures simulations de ruissellement. Le ruissellement simulé pour les bassins versants de jauge Meki et Katar a contribué respectivement à 855 mm et 524 mm à l'afflux du lac. Le ruissellement des bassins versants non jaugés est d'environ 182 mm, ce qui représente 8,5% de l'apport total du lac. La simulation du niveau d'eau du lac montre une bonne concordance de 1986 à 2000, mais une détérioration de la concordance après 2000, qui est principalement attribuée à une erreur dans l'un des termes du bilan hydrique et aux influences anthropiques. Dans l'ensemble, cette étude indique l'applicabilité de l'estimation des précipitations par satellite CHIRP pour les études du bilan hydrique des lacs dans la région où les données sont rares dans la vallée centrale du Rift en Éthiopie. L'estimation du prélèvement d'eau réel du lac Ziway a montré que chaque année 37 Mm3 d'eau sont prélevés pour l'état actuel. Lorsque les futurs plans de développement seront pleinement mis en œuvre, la quantité annuelle estimée de captage d'eau augmentera de 2,5 fois (soit 94 Mm3), ce qui entraînera une baisse du niveau d'eau du lac de 0,94 m et une réduction de la surface de 38 km2. Cela entraînera par conséquent une réduction de 26% du volume de stockage réel par rapport à l'état naturel de base. Les résultats de la simulation WEAP pour l'ensemble du bassin des lacs CRV ont révélé que pour le développement à long terme une moyenne de 223,02 Mm3 de demande en eau et 176,6 Mm3 d'eau détournée du lac et de ses affluents. Cela donnera une demande annuelle non satisfaite de 46,5 Mm3 dans le bassin central des lacs de la vallée du Rift. Il a également constaté que la plupart des programmes de développement des ressources en eau dans tous les bassins versants auront des demandes non satisfaites dans les scénarios à long terme plus élevés que dans le développement actuel. Cela a donc révélé une baisse annuelle moyenne du niveau de l'eau du lac de 2, 0,97 et 2,1 m pour le lac Ziway, Langano et Abiyata, respectivement. Par conséquent, cette étude indique que les impacts actuels du développement des ressources en eau autour du lac sont substantiellement importants et vont s'accentuer dans les futurs plans de développement. Par conséquent, l'étude suggère une gestion intégrée de l'eau du lac et de ses bassins versants

Thesis (Ph. D.)--University of Wisconsin--Madison, 1988.
Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 125-139).

碩士
中原大學
土木工程研究所
95
ABSTRACT Keywords：ground improvement, level grouting Many domestic constructions carried out in poor geologic conditions have taken the ground improvement as the first item of treatment, for the convenience of follow-up item.In the flabbiness stick to a soil layer carry on site improvement already have many work methods can be provided as reference usage, however Taipei mass transit Nei-Hou line CB420 block mark for domestic the shield tunnel cross an airport under it engineering, need to make an upper bound and a lower bound tunnel,and a connoction for averting imminent danger, because of construction district in Taipei Sungshan airport under it position special, and be subjected to only for flights careful condition, can't on the ground in traditional way get down make infuse syrup with carry on a soil layer of improvement is needing in already the completion the shield the tunnel infuse syrup by level of the way carry on a soil layer improvement a construction, this research introduction in Japan develop many usages of the double grid tube infuse syrup work method, its application is in Sungshan of airport apron under, shield tunnel up and down go a line contact channel site provement before making infuse syrup. Airport site in Sungshan belongs to Taipei bottom of river in basin Keelung weak glue a soil layer, this research first explains this kind of pair grids tube infuses syrup site improvement of construction procedure method, then examine through infuse syrup to influence after improving the back it sticky the soil layer the strength and the rightness taxiway apron in the airport before.The description double in text grid tube infuses the improvement scope of the syrup work method site, infusing syrup part to make in proper order, the material go together with a ratio, use a machine tool equipment and infuse amount of Zhu etc., go to whole construction procedure and step content, and infuse syrup to assist with various monitors in the homework in the site improvement, in order to observe contact channel to make win various variety situation. BE contacting the improvement completion of the channel site juniors to go structure to open to dig a construction, examine sticky the soil layer is after improving its close degree, through take out to measure sampling the soil body average strength to reach to a 523 kPa（5.23 kgf/cm2）, really reach construction technical specification big is 2 strength targets in the 200 kPa（2 kgf/ cm2）, the manifestation double grid tube infuse syrup site to improve a work method in the flabbiness sticky in the soil layer make result good, also very suitable for of special geography make, there is the advantage of construction convenience, can for thereafter meet similar geology condition and geography environment factor reference use.

Foundation in simple term is a part of structure through which load is finally transmitted to the soil. Settlement of foundation is an important criteria to understand the failure of foundation. In eccentrically loaded footing the settlement observed is different from concentric loaded footing hence it becomes important to observe the change in settlement due to variation in load eccentricity. Weak soil is a problematic condition on field as settlement observed is large hence geogrid material layer is reinforced at a suitable depth to observed the change in settlement. In the present study eccentric load is applied on a rectangular model footing at different values of eccentricity and by placing geogrid layer at different depth below the footing in weak soil. A uniformly increasing load is applied at a particular load eccentricity & for a geogrid layer and the settlement is noted for different load values. As a result the settlement observed in case of reinforced case is less than unreinforced case and with increase in eccentricity upto kern boundary the nature of settlement observed is different from the case when the load is applied outside the kern boundary.

碩士
國立高雄應用科技大學
土木工程與防災科技研究所
92
This research tried to use sludge, and tradition material that included fly ash, lime, and cement material to mix with cohesive soils. Design the admixing range of 2%, 4%, 8%, and 16%. According to the results of pH trial, the Ca followed Pozzolanic Reaction to reduce, and pH value also to be reduced by Curing period, including sludge/cement, sludge/lime, and fly ash. The results of Compaction test that appeared adding sludge, sludge/cement, sludge/lime, and fly ash would make unit weight reduced, so did plastic index. Moreover, by adding sludge, sludge/cement, sludge/lime, and fly ash could be helped the strength for increasing, especially sludge/cement can increase 2 ~ 4 times. When sludge content was added to the soft soil by weight at UUU test results, c value and friction angle was obviously increased and reduced individual. The high pressure permeability test shown that it was advantage of adding stabilized material by weight, but the sludge/cement and sludge/lime have reduced the permeability behavior with long-term curing period. By SEM-EDX test, the sludge contained 40~50 percentage of Pozzolanic material in relatively quantity, including 9% calcium. The silicate calcium hydration and ettringite produced after adding Stabilized material which was like lime or cement. And at different curing period the diffraction of C-S-H was raised by X-ray diffraction test, and the relative intensity was increased.

Since the horrific attacks on September 11th 2001, the United States government and research community have been focused on how to better protect US assets across the Globe. This push for safety led the research community to develop “F2656-07 Standard Test Method for Vehicle Crash Testing of Perimeter Barriers” in 2007 which standardized the method of validating a perimeter security barrier’s ability to withstand an impact from an attacking vehicle. Many of these security barriers rely on weak cohesionless soils to stop attacking vehicles. Designers currently rely heavily on hand calculations and engineering judgment when sizing these installations. This simplified analysis is generally used because of the complex nature of these soils under impact. These soils could be simulated in advanced finite element simulations; however, traditional modeling techniques will not allow for the simulation of these complex behaviors. Due to the complex nature of these simulations, new modeling techniques need to be evaluated and their use needed to be perfected. From this, a new method for creating a predictive simulation of a low speed impactor into a weak cohesionless soil was generated. This paper presents the development of a method by which a predictive simulation was created using only standard soil tests parameters. This paper also presents measured data from physical impact tests utilized to validate the method by which the simulation was generated. Next, the paper gives a detailed comparison of the results of the physical testing and the simulated impacts. The paper finally gives a summary of where the method is successful and where it needs improvement. The resulting methodology developed in this paper defines a reasonable process for creating a predictive simulation of a rigid impactor penetrating weak cohesionless sands. This finding is validated by a reasonable correlation between the measured and simulated impact penetrations. This paper also highlights the high variability of measured penetrations when testing with these soil materials.

碩士
義守大學
土木與生態工程學系碩士班
95
With the quick development of city and the city river regulations, sewage sludge produced from wastewater treatment plants increases gradually year by year. How to effectively reuse sewage sludge ash becomes an important issue for the development of the future cities. On the other hand, with the limited land resource in Taiwan and the constant growing in geotechnical engineering applications, the development of soft ground becomes inevitable. Hence, cement is one of many stabilizers applied to improve the soft soil. Sewage sludge, after incinerated at high temperature, possesses the pozzolana as cement and can be applied to improve the soft subgrade soil. In this study, the soil sample collected is a cohesive soil and is characterized as A-4 (less-compressible clay) soil. The soil sample will mix with the incinerated sewage sludge ash, sludge/cement, sludge/lime, and nano-SiO2 additive to carry out the stabilization treatment. The mix ratios for sludge/cement and sludge/lime are assigned at 1/1, 2/1. 3/1, and 4/1. With the help of the basic soil tests and microscopic examinations, the properties such as workability, strength, permeability, and shear strength of improved soft subgrade soil, as well as the optimum mix ratio of soil and ash would be obtained. Test results indicate that incinerated sewage sludge ash can improve the properties of soft subgrade soil. However, the stabilization treatment by using sludge ash can only achieve to certain extent. Yet, the additions of cement and lime to sludge ash can improve the results of the stabilization for soft soil. Furthermore, the addition of nano-SiO2 to sludge ash, sludge/cement, and sludge/lime can also help improve the stabilization for soft subgrade soil.

Geokunststoffe sind beständige Produkte aus Polymeren, die in Boden eingelegt werden um geotechnische Probleme zu lösen. Eine Kategorie der Geokunststoffe sind Geogitter, bei denen die Längs- und Querelemente eine offene, gitterförmige Struktur bilden und die meist zur Bodenbewehrung eingesetzt werden. Ihre Verwendung zur Bewehrung von gering tragfähigen Böden für kunststoffbewehrte Erd- und Stützbauwerke kann enorme ökologische und ökonomische Vorteile bieten. Trotz der Tatsache, dass die Verwendung von Geogittern in den letzten Jahren stark zugenommen hat, sind die Grundlagen zum Bau und zur Bemessung limitiert. Besonders die Schlüsselfrage, wie Geogitter und verschiedene Lockergesteine in unterschiedlichen Belastungssituationen interagieren, ist ingenieursmäßig nur lückenhaft untersucht worden. Im Rahmen dieser Dissertation wurde deshalb in über 250 großmaßstäblichen Scher-, Herauszieh- und Reibungsversuchen das Verbundverhalten Geokunststoff/Locker¬gestein eingehend untersucht. Dazu wurden 14 handelsübliche Geogitter, die teilweise auch modifiziert wurden, in dem Interaktionsprüfgerät des Institutes für Geotechnik der TU Bergakademie Freiberg mit verschiedenen Böden systematisch getestet. Die vielen Versuchsanordnungen und die aus ihnen abgeleiteten Überlegungen und gewonnenen Erkenntnisse belegten, dass die wichtigsten Parameter interagieren, und zwar in verschiedenen Abhängigkeiten wie weitere Variationen der Bodenparameter (Kornverteilung, Wassergehalte, Verdichtung, Bindemittelzusatz etc.), der unterschiedlichen Geogitterparameter (Oberflächenbeschaffenheit, Struktur, etc.) und der Belastung gezeigt haben. Darüber hinaus wurde das Interaktionsprüfgerät für zukünftige Versuche weiterentwickelt (Entkopplung des Versuchseinbaus vom Versuchsgerät usw.). Der Fokus der Forschungsarbeit lag dabei in der Schaffung von Grundlagenkenntnissen für den gemeinsamen Einsatz von bindigen Lockergesteinen und Geokunststoffen. Bei rolligen Böden zeigte sich, dass die Rautiefe sich stärker (positiv) auf die Widerstände auswirkt als bei den bindigen Böden. Hingegen waren bei bindigen Böden die Auswirkungen durch eine Erhöhung der Querelemente deutlicher. Darüber hinaus konnte gezeigt werden, dass dreidimensionale Querelemente das Verbundverhalten verbessern und Tests an Geogittern mit einem größeren Verhältnis von Öffnungsweite zu Maschenweite zeigten höhere Adhäsionswerte. Die Reibungsversuche hatten einen gleichmäßigeren Verlauf und geringere Streuungen zwischen den unterschiedlichen Geogittern, weshalb aufgrund der deutlicheren Unterschiede zwischen den Produkten bei den Herausziehversuchen detaillierte Schlussfolgerungen gezogen werden konnten. Die vorliegende Arbeit leistet einen Beitrag zur Verbesserung der Bemessungsgrundlagen und ermöglicht ein detaillierteres Verständnis des Verbundverhaltens. Des Weiteren werden Vorschläge ausgearbeitet die im Labor erzielten Ergebnisse auf die Baupraxis zu übertragen, wie zum Beispiel durch das Vermeiden von Trennflächen zwischen Geogitter und Boden bei der Verdichtung.
Geosynthetics are durable polymeric products placed in soil to help solve civil engi-neering problems; one category of these is geogrids. Geogrids are polymers formed into an open, grid-like configuration and function primarily as soil reinforcement. Their use to reinforce soil with weak bearing capacity could have big ecological and economical advantages. Although geogrid use has grown in recent years, there is still limited design information available due to the wide variety of design configurations and soil variability. One of the key factors lacking for more widespread engineering implementation is a greater understanding of the interaction between various geogrids and soil combinations when exposed to different load effects. In more than 250 shear, pull-out, and friction tests, this interaction behavior was examined in detail. Fourteen general geogrids (sometimes additionally modified) using dif-ferent soil types were systematically tested in the Interaction Testing Device at the Geotechnical Institute of the TU Bergakademie Freiberg. Combining the huge quantity of test results with a theoretical analysis, the main parameters which affect soil behavior could be defined. Furthermore the Interaction Testing Device could be improved for test in future. Our analysis showed us that the roughness of the geogrid has more of a beneficial impact on the strength of frictional soils than it does for silty soils. Silty soils however, were more affected by the height of cross elements in the geogrid than other types. It was also observed that 3D elements in the cross machine direction improve the interaction behavior. Tests with geogrids which have a bigger ratio of opening size to mesh size showed higher adhesion values. The friction test results were more regular, had a uniform progress and had smaller differences between geogrid configurations. Therefore, conclusions with higher certainty could be drawn from the pull-out tests with the differential results. The present research contributes to the limited design information to help provide a better understanding of the interaction behavior. Furthermore, suggestions are given to use the laboratory detected results in real-world applications, one of which is the way of compaction to minimize the potential for creating a slip-surface between the geogrid and soil.

In the present study α-Al2O3 powders of nanometric size were successfully synthesized by sol-gel method using two different precursors, one using aluminium chloride(AlCl3),ethanol(C2H5OH) and ammonia(NH3) followed by calcination at 1200oC for 2 h in a furnace, and the second process using aluminium nitrate (Al(NO3)3), malic acid (C4H6O5) and polyvinylpyrrolidone, PVP ((C6H9NO)n) followed by heat treating at 1250°C for 2 h. The alumina formed were analysed by X-ray diffraction (XRD) and particle size analysis to characterize the powders in terms of their crystallinity and their crystallite size. Further characterizations of particles were carried out using scanning electron microscopy (SEM), high resolution transmission electron microscope (HRTEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) techniques. It was found that much finer particle size of α-Al2O3 could be achieved when Al(NO3)3 was used as a precursor. The decrease in size accompanied by an increase in aspect ratio makes it an ideal reinforcing agent for high strength composites and results in its highly superior properties. The present study also involved the development of Zn-Al2O3 composites by reinforcing the Zn-matrix with α-Al2O3 as reinforcement. α-Al2O3 is very attractive due to their unique combination of excellent mechanical properties and high thermal stability which makes them an ideal reinforcing agent for high strength composites. Zn-Al2O3 composites were developed containing 50 and 60 vol.% α-Al2O3 by an ex-situ process that includes blending commercially available Zn and α-Al2O3 powders together in required compositions followed by compaction at 300 MPa and heat treatment at 500oC for 2 h. The Zn-Al2O3 composites fabricated were analysed by using optical microscopy, SEM and EDX. Mechanical properties like wear resistance and hardness of the composites were analysed to find out the effect of the addition of α-Al2O3 in the Zn-matrix. It was found that addition Al2O3 to Zn matrix improved the hardness as well as the wear resistance of Zn