Tese de mestrado integrado. Engenharia Civil ( Especialização em Geotecnia). Faculdade de Engenharia. Universidade do Porto. 2009

Rapid and sustainable economic growth and progressive social and spatial development through industrial development, has been a persistent challenge for the Sub-Saharan Africa (SSA). A commonly held "solution" to this challenge has been to provide access of manufactured goods from the SSA-region to the dynamic markets of the affluent North. This perceived wisdom led to the passing of the African Growth and Opportunity Act (AGOA) in 2000 by the 200th Congress of the United States of America. In this exploratory study, the experience of Lesotho with AGOA, with specific reference to the economic and spatial development outcomes of the Act in the country, is explored. The findings of the study reveal that the larger settlements where the AGOA-factories are located have shown little improvement, neither from an economic, nor from a spatial perspective. The same applied to villages to which AGOA factory workers sent their remittances. This was due to the meagreness of the remittances a function of the low wages paid in the factories and the resulting limited disposable income to support small-scale businesses in these villages. While AGOA did result in the creation of tens of thousands of job opportunities for unskilled and semi-skilled Basotho youth, it did not provide them with portable skills for use after leaving the factory floor. AGOA was also not found to have motivated the youth or local entrepreneurs to tap into the manufacturing sector. On the spatial development side, a number of landlords in the larger settlements subdivided their land and built residential rental units for the factory workers. Some landlords also sold their land illegally and informally, resulting in haphazard land development. The research findings suggest that, while "trade and development boosting tools", like AGOA, may be useful in providing term-based job opportunities for unskilled workforce, they will most likely not have as significant a positive impact on (1) the local economy, (2) the creation of an indigenous industrial class, or (3) the building of sustainable human settlements. Other supporting instruments, in addition to tools such as AGOA, will need to be developed locally, to achieve these goals. In addition to the research findings providing an insight into the experience of Lesotho with AGOA, they should also be of assistance to scholars and policy-makers working on the development of trade-driven tools in support of struggling regions. / Dissertation (MTRP)--University of Pretoria, 2017. / Town and Regional Planning / MTRP / Unrestricted

Considering the similarity between the mechanical behavior of artificially cemented soils and rock masses, this study proposes a methodology to obtain the envelopes resistance of artificially cemented soils, using the Hoek-Brown failure criterion. The proposed methodology consists basically in performing two triaxial tests, with the soil non-cemented and cemented with a high cement content, and estimate the strength envelopes for intermediate cement contents, using the equations presented in this research. To develop the methodology, initially, a number of unconfined compression tests and triaxial tests were carried out in order to quantify the influence of the porosity/cement ratio (n/Civ) on the strength parameters of the cement mixtures used. From the tests results and the Hoek-Brown failure criterion, new equations were developed to calculate the envelope parameters (a, m, s), as functions of porosity/cement ratio. The proposed method was applied to triaxial tests data presented in four different studies and the results showed that the Hoek-Brown envelope is suitable to represent the resistance of artificial cemented soils, being able to incorporate the effects caused by the confining pressure and by the cement content. The envelopes estimated and those obtained from the triaxial tests were very close, indicating that the proposed methodology can be used with a reasonable degree of reliability. The results obtained with the proposed methodology were used to simulate, by the Finite Element Method, the pressuresettlement behavior and the variation of the safety factor of a shallow foundation bearing on a double-layered system formed by an artificially cemented soil layer overlaying a soil stratum. The simulations were performed using as variables the cement content of the enhanced layer and the relationship between the thickness of the treated layer (H) and the diameter of the foundation (D). The results show that the use of artificially cemented layers considerably increases the vertical pressure required for an specific settlement and also the foundation safety factor. Thus, the execution of shallow foundations, replacing deep foundations, becomes feasible / Considerando a semelhanÃa existente entre o comportamento mecÃnico dos solos artificialmente cimentados e dos maciÃos rochosos, o presente trabalho propÃe uma metodologia para a obtenÃÃo das envoltÃrias de resistÃncia dos solos artificialmente cimentados, utilizando o critÃrio de ruptura geral de Hoek-Brown. A metodologia proposta consiste, basicamente, em realizar dois ensaios triaxiais, um com o solo nÃo cimentado e outro com o solo cimentado com um teor de cimento elevado, e estimar as envoltÃrias de resistÃncia para os teores de cimento intermediÃrios, atravÃs das equaÃÃes desenvolvidas. Para o desenvolvimento da metodologia, inicialmente, foram realizados ensaios de compressÃo simples e triaxiais nÃo drenados, com o objetivo quantificar a influÃncia do fator vazio/cimento (n/Civ) sobre os parÃmetros de resistÃncia das misturas cimentadas utilizadas. A partir dos resultados dos ensaios de resistÃncia e da equaÃÃo geral do critÃrio de Hoek-Brown, foram desenvolvidas equaÃÃes para calcular os parÃmetros da envoltÃria (a, m, s), em funÃÃo do fator vazio/cimento. A metodologia proposta foi aplicada aos resultados dos ensaios triaxiais apresentados em outros quatro trabalhos e os resultados mostraram que a envoltÃria de Hoek-Brown à adequada para representar a resistÃncia dos solos artificialmente cimentados, sendo capaz de incorporar os efeitos causados pela tensÃo confinante e pelo nÃvel de cimentaÃÃo. As envoltÃrias estimadas e as obtidas com os ensaios triaxiais ficaram bem prÃximas, indicando que a metodologia proposta pode ser empregada com um razoÃvel grau de confiabilidade. Os resultados obtidos com a metodologia proposta foram utilizados para simular, atravÃs do MÃtodo dos Elementos Finitos, o comportamento carga-recalque e a variaÃÃo do fator de seguranÃa de uma fundaÃÃo superficial assente sobre um sistema de dupla camada, sendo a superior cimentada. As simulaÃÃes foram realizadas utilizando como variÃveis o teor de cimento da camada reforÃada e a relaÃÃo entre a altura da camada cimentada (H) e o diÃmetro da fundaÃÃo (D). Os resultados obtidos mostram que a utilizaÃÃo de camadas artificialmente cimentadas eleva consideravelmente as tensÃes verticais necessÃrias para um recalque relativo especÃfico e, tambÃm, o fator de seguranÃa da fundaÃÃo. Com isso, a execuÃÃo de fundaÃÃes superficiais, em substituiÃÃo a fundaÃÃes profundas, torna-se viÃvel.

Goal of this paper is defining Hoek - Brown failure criterion for samples of granodiorite from possible site of Czech deep geological repository - Brezovy potok. Paper includes triaxial testing, defining HB failure criterion for intact rock, rock massif and evaluation of available data. Other methods for defining parameters of HB failure criterion (eg. GSI and mi) are also explored. Comparisons for all parameters and data are given. Paper is concluded with simple numerical model, using results from laboratory testing and literature review.

Genom samarbete med konsultföretaget Tyréns har detta examensarbetet undersökt hur en säkrare prognos kan erhållas för bergprojektering. Till underlag undersöktes ett aktuellt projekt i Jakobshyttan, med fokus på släntstabilisering. Med avseende att identifiera de osäkerheter sompåverkar bestämmandet av bergets parametrar har parametrarnas inverkan på stabiliteten och dess kostnadseffekt på stabilisering studerats. Framtagandet av de relevanta parametrarna identifierades genom litteraturstudie, Tyréns bergtekniska prognos, relevanta handlingar för området och studiebesök på arbetsplats. Vidare utfördes en känslighetsanalys på de parametrar som var relevanta för stabilitets problematiken, för att utvärdera de kritiska gränserna för respektive parameter. För arbetet användes Barton och Bandis brottvillkor baserat på den bergtekniska informationen som fanns tillgänglig. Slutligen utfördes en kostnadsberäkning för deparametrar som identifierats med eventuella osäkerheter, för att ge perspektiv på effekten av osäkerhet. Resultatet visade att parametrarna JRC och residualfriktionsvinkel hade kraftig inverkan på stabiliteten. Parametrarnas värde bestämdes enligt föreslagen metodik från Trafikverkets handbok för bergprojektering och uppskattats genom tabeller baserade på empiriska fall. Sammanfattningsvis har den rekommenderade metodiken från Trafikverket ansetts som bristfällig och ger utrymme för felbedömningar i projekteringsskedet. / Through collaboration with the consulting company Tyréns, this thesis has investigated how a more reliable forecast can be obtained for rock design. As a basis, a current project in Jakobshyttan was investigated, focusing on slope stabilization. With regard to identifying the uncertainties that affect the determination of the rock parameters, the parameters impact on thestability and its cost effect on stabilization have been studied. The relevant parameters were identified through literature study, Tyréns forecast of rock technology, relevant documents for thearea and study visits to the workplace. Furthermore, a sensitivity analysis was performed on the parameters that were relevant to the stability problem, in order to evaluate the critical limits foreach parameter. The thesis used Barton and Bandis failure criteria based on the rock technical information that was available in the project. At last a cost calculation was performed to provide perspective on the effects of each of the parameters identified as being uncertain. The results showed that the parameters JRC and residual friction angle had a big impact on the stability. The value of the parameters was determined according to the proposed methodology from the customer, the Swedish Transport Administration, and was estimated through tables based on empirical cases. In summary, the recommended methodology from the Swedish Transport Administration has been considered deficient and leaves room for incorrect assessments in the design phase.

AN ABSTRACT OF THE THESIS OF Behrooz Abbasi, for the Master of Science Degree in Mining and Mineral Resources Engineering, at Southern Illinois University Carbondale TITLE: A NUMERICAL ANALYSIS OF MINE INTERSECTIONS AND SUPPORT SYSTEMS FOR STABILITY MAJOR PROFESSOR: Dr. Yoginder P. Chugh Back ground: Partial extraction room-and-pillar mining systems provide about 60 % of the underground coal mined in the USA. This mining system develops 3-way and 4-way intersections. Rock falls related to fatal and nonfatal injuries in the USA for the period 2002 to 2007 identified that about 70% of these falls occur at intersections even though they represent only about 20-25 % of the area mined. A recent study on 2004 to 2008 roof-falls data base (RFDB) for Illinois mines, found that over 80% of these falls occurred at intersections. Thus, there is a significant need to improve stability of coal mine intersections if fatal and nonfatal injuries are to be controlled. The overall goal of this research is to develop an improved scientific understanding of stress distribution and instability around a 4-way intersection. An additional goal is to evaluate primary and secondary support layouts for improved stability around 4-way intersections. The following specific tasks were established for this research. * Perform 3-D numerical analyses to develop a better understanding of stress, strain and displacement distributions and associated instabilities around a 4-way intersection to identify ground support requirements. * Identify primary and secondary supports systems that may be suited to meet ground support requirements in (1) above. * Perform numerical analyses with identified primary and secondary supports installed to assess improvements in stability around an intersection. Analyses results show that pillar ribs across an intersection fail first and lead to progressive failure of immediate roof layers. The failure of immediate roof layers extends about 1.8m. In detail, coal ribs around the intersection corners mostly fail due to tensile stress, while roof and floor strata fail due to shear stresses and rib center fail due to combination of shear and tension mechanism. Primary supports significantly improve stability, but they are not adequate to ensure stability of four-way intersections. Secondary supports are needed to further improve stability of intersections. Also, based on the failure analysis a new secondary support system plan was proposed and analyzed.

Tato diplomová práce se zabývá zhodnocením inženýrskogeologických poměrů mostu na stavbě č. 519 silničního okruhu kolem Prahy včetně vyšetření stability skalních svahů v místě předpokládané výstavby. Jedná se o přemostění hlubokého erozního údolí Vltavy, na jehož svazích vystupují na povrch horniny svrchnoproterozoického stáří. Na lokalitě byly zhodnoceny pomocí rešerše archivních podkladů, vlastní rekognoskace a laboratorních zkoušek, geologické, hydrogeologické a inženýrskogeologické poměry, které jsou přehledně uvedeny v inženýrskogeologické mapě v měřítku 1:2000 a řezu 1:500. Jako podklad pro vyhodnocení stability skalních svahů sloužila podrobná dokumentace skalních výchozů. Samotné vyšetření stability proběhlo pomocí klasifikace Slope Mass Ratting a Marklandova testu pro stereografickou projekci. Na výstupech práce je souhrnně popsán horninový masiv včetně mapy stability skalních svahů v měřítku 1:500 a popsány základové poměry uvažovaného mostu.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, February 2015. / Due to its geographical location, poor economic situation and geological features that are characterised by mostly mountainous terrain, Lesotho is vulnerable to hazardous events associated with climate, such as drought, floods, heavy snow, and severe frost. This research explores factors underlying spatial vulnerability of places to natural hazards in south-western Lesotho. Prior vulnerability assessments in Lesotho have investigated vulnerability in terms of identifying populations that are most food insecure and vulnerable to hunger. By broadening the scope of vulnerability to include biophysical and socioeconomic characteristics, the study emphasises the concept of place vulnerability as a foundation for understanding Lesotho’s vulnerability to natural hazards. Spatial orientation of vulnerability within a geographical area provides an easy way for planners and decision makers to identify areas that may require additional resources in order to prepare for disasters. To date, no quantitatively based vulnerability assessment has been undertaken in Lesotho, so this study is one of the first to assess place vulnerability to natural hazards in Lesotho using GIS and it emphasise the role of geography of a place.

Les projets de tunnels dans des milieux rocheux de faibles caractéristiques mécaniques, usuellement regroupés sous l'appellation sols indurés roches tendres (S.I.R.T.), se heurtent à de multiples difficultés. Ces matériaux présentent des spécificités de comportement qui les rendent atypiques dans les contextes usuels de la mécanique des sols comme de la mécanique des roches, compliquant les dimensionnements et pouvant engendrer des surcoûts importants pour les maîtres d'ouvrage. En se limitant aux S.I.R.T. modélisables par une approche continue, la non-linéarité du critère de rupture, les couplages hydromécaniques et la dépendance de la déformabilité à l'état de contrainte apparaissent comme des traits de comportements susceptibles d'influencer significativement la phase de creusement (équilibre à court terme). Bien que ces propriétés puissent être prises en compte de manière adéquate dans des modèles numériques, la pratique des calculs de tunnel a montré de longue date l'intérêt des méthodes simplifiées comme l'approche convergence-confinement. Elles permettent un prédimensionnement raisonnablement représentatif au moyen de formulations peu complexes et favorisent la réalisation d'études de sensibilité grâce à leur mise en œuvre simple et rapide. À partir d'une approche de type " milieux poreux ", prenant en compte la compressibilité des différents constituants du matériau, et d'une représentation adimensionnelle du critère de rupture de Hoek-Brown (incluant les régimes d'arête), de nouvelles formulations permettant le calcul des courbes caractéristiques du terrain sont donc présentées. Après s'être intéressé dans un premier temps à la seule non-linéarité du critère de rupture, avec un milieu monophasique, une complexification progressive du problème est mise en œuvre pour prendre en compte des situations biphasiques drainées ou non drainées. À chaque fois une résolution complète est proposée, aboutissant à des formulations explicites ou à des équations intégrables aisément par une méthode numérique à un pas. Un outil sous forme de tableur, directement utilisable et démontrant la simplicité de mise en œuvre des solutions établies, est systématiquement fourni. Le cas non drainé est ensuite complété par un schéma de calcul intégrant une élasticité non-linéaire de Fahey-Carter, avec la méthode des matrices de transfert. La partie finale du travail permet d'aborder l'applicabilité de ces développements analytiques à un cas réel, le tunnel d'Arbus. Elle souligne quelques difficultés de détermination de paramètres à partir de campagnes d'essais " standard " et insiste sur la variabilité naturelle des matériaux dans une géologie molassique du piémont pyrénéen. Ce contexte met en relief les avantages des méthodes développées : outre une représentation plus satisfaisante du comportement du milieu, elles permettent à peu de frais d'identifier les paramètres les plus influents sur l'équilibre massif - soutènement et d'aborder la problématique des incertitudes dans le dimensionnement. Les calculs font également ressortir l'intérêt des modèles à élasticité non linéaire, avec une prise en compte plus appropriée de la déformabilité du matériau mais aussi une réduction de la sensibilité du modèle à la variabilité des paramètres élastiques. Les approches présentées conservent néanmoins certaines limites, comme la nécessaire distinction des équilibres court terme et long terme, l'hypothèse de contrainte initiale hydrostatique qui se révèle au final assez forte et le problème de la représentation du soutènement qui mériterait d'être davantage approfondi même si des méthodes acceptables sont d'ores et déjà disponibles dans la littérature.

Closely jointed greywacke rock masses are widespread throughout both the North and South Islands of New Zealand and much of New Zealand's infrastructure is constructed upon greywacke rock masses. This thesis deals with determining the rock mass strength of unweathered closely jointed New Zealand greywacke rock masses. Currently, the estimation of rock mass strength and deformability is reasonably well predicted through the use of such empirical failure criteria as the Hoek-Brown failure criterion and empirical expressions to predict deformability. However, previous studies upon predicting the strength and deformability of unweathered closely jointed New Zealand greywacke rock masses has shown that existing empirical methods of determining strength and deformability are unsatisfactory. The problem with predicting rock mass strength and deformability moduli of New Zealand greywacke and the lack of adequate data to calibrate a failure criterion was the starting point for this work. The objective of this thesis was to increase the knowledge of intact and defect properties of closely jointed greywacke, develop reliable rock mass data with which to calibrate a failure criterion and improve the ability to estimate the rock mass strength of greywacke rock masses. A review of existing failure criteria for rock masses was conducted and of these criteria, the Hoek-Brown rock mass failure criteria was selected to calibrate to both the intact rock and rock mass failure data, because of its broad acceptance in the rock mechanics community. A database of greywacke properties was developed based on previous studies upon unweathered greywacke around New Zealand and is attached to the thesis as an Appendix. The database included descriptions of greywacke defect properties and mechanical properties of the intact rock and joints. From this database, inputs could be justified for numerical modelling and later analyses of failure criteria. Records from the construction archives of the Benmore and Aviemore hydroelectric power projects in the South Island of New Zealand were reviewed to obtain information and results from a series of shear tests carried out on unweathered closely jointed greywacke in the 1960s. Data on rock mass strength at failure and rock mass deformability were extracted from these records to assess the predictability of the failure criterion and deformability expressions. Problems experienced during the shear tests at the Aviemore dam site created doubt as to the actual rock mass strengths achieved at failure. The behaviour of these tests was studied using the finite difference code FLAC. The work was aimed at investigating the potential for transfer of shear force between the two concrete blocks sheared in each test and the impact shear force transfer had upon the likely normal stresses beneath each block at failure. The numerical modelling results indicated that a combination of preferential failure occurring in one direction, and doubt in the actual normal load applied to the concrete blocks during testing lead to premature failure in the blocks sheared upstream. The blocks sheared in the opposite direction failed at normal stresses that are reflective of the strength of an unweathered greywacke rock mass, but these results could be explained by failure occurring along defects therefore not satisfying the assumptions of homogeneity typically required of a rock mass failure criterion. The Hoek-Brown failure criterion for intact rock was investigated by fitting it to the largest intact greywacke datasets. For a full set of test data (i.e. including tensile data), the Mostyn & Douglas (2000) variant of the Hoek-Brown failure criterion gave the best fit for a full set of rock mass data. A multiple regression method was developed which improved the fitted curve to intact data in the tensile region and gave the best estimate of tensile strength if no existing lab results for tensile strength were available. These results suggest that the Hoek-Brown failure criterion is significantly limited in its applicability to intact NZ greywacke rock. Hoek-Brown input parameters different to those suggested by Hoek et al (2002) are recommended for using the Hoek-Brown failure criterion for intact NZ greywacke. For closely jointed NZ greywacke rock masses, the results from the shear tests at Aviemore and Benmore were separated into different GSI classes and Hoek-Brown envelopes fitted to the datasets by multiple regression. Revised expressions were proposed for each Hoek-Brown input parameter (mb, s, ab) as a function of the GSI. The resulting revised Hoek-Brown failure envelopes for NZ greywacke offer a significant improvement on the existing criterion used to predict the strength of NZ greywacke intact rock and rock masses. The differences in the behaviour of the reaction blocks that failed before the test blocks and the reduction in rock strength due to sliding along defects from that predicted could be reasoned from recorded observations and the behaviour of the concrete blocks during the shear tests. This study has clearly illustrated the need for continued research in this area. This includes (1) a means of assessing the role of defects upon the shear strength of closely jointed greywacke rock mass into a failure criterion, (2) further modelling of the in-situ shear tests by a discrete element procedure to expressly determine the role of the defect on failure, (3) more testing on rock masses to obtain more data to calibrate a rock mass failure criterion, and (4) more studies on predicting the strength of extremely disturbed rock masses.