Geopolymerization is a chemical reaction process, reacting SiO₂ and Al₂O₃ with alkaline solutions, which can transform aluminosilicate solids or particles to polymer materials. Geopolymers have many engineering applications such as cementation binders for construction and solidification or encapsulation of hazardous heavy metals. Mine tailings mainly consist of SiO₂ and Al₂O₃. Theoretically, mine tailings can be used as source materials for geopolymerization. However, for most researchers, they use fly ash, metakaolin or furnace slag as source minerals, because these minerals are much more reactive with alkaline solutions. Mine tailings are naturally-forming minerals and are considered to be inert in geopolymerization. How are mine tailings to be activated through different reaction conditions? We conducted several tentative or preliminary experiments to study the geopolymerization process step by step. We tried different methods to react mine tailings with alkaline solutions. Mine tailings were submerged into alkaline solutions in a plastic bucket for 6 days in room temperature (20-25 °C). We wanted mine tailings to be activated by soaking. The results were not satisfying. Then we tried to react mine tailings with alkaline solutions at 60 °C and 90 °C. After analyzing, we found that the results were not satisfying either. So, we conducted simplified geopolymerization experiments in order to better understand the chemical reaction mechanism. Pure SiO2 and Al2O3, which were two major reactants, were employed to simplify and simulate the geopolymerization process. We drew some useful conclusions such as that geopolymerization took place at elevated temperatures; Al₂O₃ almost did not react with alkaline solutions at low temperatures, etc. We conducted experiments at elevated temperatures (150 °C, 180 °C, 210 °C). Different levels of pressure (5 MPa, 10 MPa, 20 MPa) were applied to make compact specimens. After many attempts, the results were successful. The highest mechanical strength was about 20 MPa. Most importantly, we obtained polymers produced from geopolymerzation, which could be seen by naked eyes. The experiment techniques such as scanning electron microstructure (SEM) imaging and X-ray diffraction (XRD), inductively-coupled plasma mass spectrometry (ICP-MS), and unconfined compression tests (UCS) were applied to study the geopolymerization reaction mechanism and the feasibility of using mine tailing-based geopolymers as construction materials.

155 Early Cretaceous core and cuttings samples from 15 northeast Libyan wells have been dated, mainly on the basis of dinoflagellate cyst assemblages although stratigraphically important spore and pollen taxa have also been used when dinocysts are rare, absent or not age diagnostic. Spores and pollens have also helped with palaeoenvironmental reconstructions. Six distinct associations that are both stratigraphically and palaeoenvironmentally controlled are identified; these range from Hauterivian to early Cenomanian age. ? late Hauterivian to ? middle Barremian assemblages (IA) are dominated by dinoflagellate cysts thought to indicate lower than normal marine salinities, namely Cyclonephelium hystrix, Muderongia simplex microperforata, and Systematophora spp. Barremian assemblages (IB) are characterised by the presence of Aptea anaphrissa, and those from the early to late middle Aptian (II) by several other species of Aptea, especially A. securigera and the pollen Afropollis operculatus. An inner to middle shelf, pre-Vraconian Albian association (IIIA) comprises numerous morphologically varied dinoflagellate cysts including several species of each of the genera Coronifera, Oligosphaeridium, Spiniferites and Subtilisphaera notably S.terrula, and S.deformans/S.perlucida, whereas near-shore deposits of approximately the same age (IIIB) contain fewer cysts, more miospores and some megaspores. Both reflect a regression of the sea in the region prior to a major Late Cretaceous transgression, the early stages of which are indicated by two Vraconian-early Cenomanian associations (IVA and IVB). These consist of numerous chorate and proximochorate dinoflagellate cysts including Cyclonephelium, Dinopterygium, Florentinia, Oligosphaeridium, Spiniferites, Palaeohystrichophora infusorioides and Subtilisphaera cheit. Generic and species diversity is however higher in IVA, implying deposition in more open marine conditions than assemblages identified as IVB, which contain larger numbers of miospores. The complexities of intergeneric and intra- and interspecific morphological variation are described and illustrated for several taxonomic groups, including Aptea, Coronifera, Cyclonephelium, Dinopterygium, Florentinia, Kiokansium, Occisucysta, Oligosphaeridium, Palaeohystrichophora, Protoellipsodinium, Subtilisphaera and Xiphophoridium. Several possible synonymies at both generic and specific levels are suggested, and 10 informal species and three varieties of Florentinia berran are described.

The UK Committee on Radioactive Waste Management (CoRWM) recommended, in 2006, that geological disposal coupled with safe and secure interim storage should have been the way forward for the long-term management of the UK’s higher activity wastes. The design of the underground repository contemplates the presence of bentonite plugs to seal access galleries and deposition boreholes and hence the interaction between the clay-based backfill material and the underground water. Remote monitoring of the fluid saturation of the barrier, the waste canisters and of the surrounding subsurface Geological Disposal Facility environment assumes a relevant importance to guarantee the safety of the repository and to increase the confidence and the reliance of the communities living in areas potentially affected by the repository over time. This remote monitoring of the Engineered Barrier System represents a technical challenge due to the unsuitability of some of the traditional geotechnical techniques or to the intrinsic unreliability of many geophysical prospecting techniques in providing information about the evolution of the Thermo-Hydro-Mechanical-Chemical coupling of the system over long timescales up to and including post-closure evolution. In this project, I offer an initial approach to an innovative way of using mineral magnetism, and, in particular, I analyse the possible exploitation of corrosion-induced variations of the magnetic properties of several magnetic materials to monitor water saturation in the Engineered Barrier System and its evolution through time. Initially the reactivity of several natural and synthetic materials is tested under different “extreme” conditions to analyse the feasibility of the research concept and identify the materials more adapt to carry out the job. The effects that the corrosion of the magnetic materials has on the clay matrix is also analysed in detail throughout all the thesis work. The initial tests lead to the identification of specific transitions in the hysteretic behaviour of three of the initial candidates (Nd-Fe-B, AlNiCo and SmCo alloys). These three materials are subsequently tested under conditions closer to a real “evolved” Barrier System, where the groundwater interacts, with cementiferous grout producing hyperalkaline leachates. The final tests consider the temporal evolution (after 4, 8 and 12 months) of the magnetic properties of these materials in a dysoxic environment under imposed fluid-flow. The results show a clear change in the hysteretic properties of the three materials analysed and the feasibility of the monitoring of the Barrier fluid saturation in the short-term. Furthermore, the corrosion of the magnets, under the conditions applied, did not cause formation of non-swelling clays.

<p> Unstable failure in underground mining occurs when a volume of material is loaded beyond its strength and displaces suddenly. It is recognized on various scales, from small rock bursts to the collapse of pillars or entire sections of a mine. The energy that is released during smaller scale events is manifested through the ejection of material, which can pose a hazard to the safety of miners. Larger scale events generate seismic waves as mine workings are damaged and may entrap miners or terminate production. </p><p> This dissertation focuses on the analysis of unstable failure in an underground room and pillar mining environment. The potential for violent pillar failure is assessed using numerical modeling techniques and a parametric approach to loading conditions and material strength properties. The magnitude of instability is quantified by calculating the release of kinetic energy that occurs as failure progresses in each simulation. </p><p> Fundamental mechanisms associated with the release of kinetic energy are analyzed in a series of finite difference models, and the results are compared with analytical solutions to illustrate the applicability of the energy calculations to increasingly complex modes of failure. Back analyses are performed on two room and pillar mine collapse events from the western United States by constructing large-scale models and reproducing widespread failure. The values of energy released in two-dimensional models are extrapolated by assuming a depth of failure in the third direction, and the total energy values are compared to the documented seismic magnitudes from each collapse through empirical equations. With further development of this numerical modeling approach, energy consideration may be used to study the potential for instability in a wide variety of mining excavations and identify the associated range of hazards.</p>

Source: Dissertation Abstracts International, Volume: 39-11, Section: B, page: 5301. / Thesis (Ph.D.)--The Florida State University, 1978.

Thesis (Ph. D.)--Ohio State University, 1981. / Includes vita. Includes bibliographical references (leaves 165-171). Available online via OhioLINK's ETD Center.

The purpose of this study is to analyze the combined effects of storm surge and inland rainfall on the floodplain of a coastal bayou in the Houston area using dynamic hydraulic modeling. HEC-RAS, a one dimensional flow model, was run for both the steady and unsteady states in order to analyze the linkage between inland flooding and storm surge. First, the steady model was run to give a basic understanding of the watershed. The unsteady HEC-RAS model was then evaluated in the unsteady state which allowed both rainfall and storm surge from Hurricane Ike to be introduced dynamically. This allowed for a more accurate representation of the timing of flooding characteristics of Horsepen Bayou, and the modeled hydrographs generated an excellent match against measured data in Horsepen Bayou. Using this model it was discovered that the timing of both rainfall and storm surge play a significant role in the magnitude of flooding.

Thesis (M.S.)--Boise State University, 2009. / Includes abstract. Includes bibliographical references (leaves 85-90).

Thesis (M. Sc.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Feb. 19, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Mining Engineering, Department of Civil and Environmental Engineering, University of Alberta. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains viii, 109 p. : col. ill., col. maps. Includes abstract. Includes bibliographical references (p. 54-62).