The understanding of liquefaction behaviors, related to a coal's properties and a recycle solvent's composition, is essential for the development of an efficient direct liquefaction process. In this dissertation, a study of the liquefaction behaviors of an Eastern us bituminous and four Western US subbituminous coals is presented. The experimental approach has been to examine their behaviors under various reaction conditions with in-house microautoclave reactor and Kerr McGee pilot plant liquefaction runs. In-house runs involved surveys of coal types and process solvent compositions with variations in reaction times, temperatures and atmospheres. Runs performed at Kerr McGee examined the use of tetrahydroquinoline (TBQ) as a process solvent with a Wyoming coal. Liquefaction activities were assessed through determinations of coal conversion to both solvent-soluble products and distillate yields. Per the in-house liquefaction studies, a novel microautoclave reactor design and product recovery methods were developed, evaluated and employed. The reaction chemistries of !n !!S!! metal species and basic nitrogen heterocycles were investigated specifically. Changes in trace element concentrations were ascertained by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and Size Exclusion Chromatography/ICP-AES (SEC/ICP-AES). Pates of basic nitrogen components in distillate and solvent-soluble residuum products were examined by nitrogen mass balance determinations, Gas Chromatography/Pourier Transform Infrared Spectrometry (GC/PTIR) and Gas Chromatography/Mass Spectrometry (GC/MS). Conversions to soluble products demonstrated the expected dependencies of liquefaction on coal rank, elemental composition and petrography. The western subbituminous coals showed extreme sensitivity to drying and solvent-soaking pretreatments. Metal content analyses revealed that metals exist as complexed species in the liquefaction process. Higher conversions to toluene-soluble materials were obtained with THQ in contrast to other H-donor solvents. Adduction of THQ was significant in the non-distillate product stream, however. The direct coupling of Reversed Phase HPLC separations with PTIR (RP-HPLC/PTIR) detection through on-line, post-column extraction was developed. Though intended for application to coal-liquefied product (CLP) analysis, this system was evaluated rigorously for both chromatographic and spectral performance. Throughout this investigation, the overall utility of these hyphenated methods for CLP analysis was explored. These methods demonstrated exceptional performance in providing a wealth of qualitative and quantitative information in a rapid manner. / Ph. D. / incomplete_metadata

Liquefaction ls a phenomenon where a saturated soil can temporarily lose its shear strength during an earthquake as a result of the development of excess pore pressures. For the past 25 years since Iiquefaction phenomenon was first explained, it was thought to be mainly a problem with clean sand, and most of the research has focused on these soils. However, as case history information has come to light, it has become apparent that silty sands are commonly involved, and in some cases even silts. This has generated a need for knowledge about the response of silty sands and silts under seismic loading. Related to this issue is the question of how best to determine the Iiquefaction resistance of these soils in a practical setting. This research has the objectives of providing an understanding of the behavior of saturated silty sands under seismic loading, and developing a rational basis for the use of the Cone Penetration Test (CPT) to predict Iiquefaction resistance in these materials. The study is primarily experimental, relying on laboratory and field testing and the use of a unique, large scale calibration chamber. The calibration chamber allows the field environment to be duplicated in the laboratory where conditions can be closely controlled and accurately defined. One of the first problems to be overcome in the research was to determine how to prepare specimens of silty sands that would reasonably duplicate field conditions in both the small scale of the conventional laboratory tests, and the large scale of the calibration chamber. Out of four different methods explored, consolidation from a slurry proved to be best. Two silty sands were located which had the desired characteristics for the study. Field work, involving both the Standard Penetration Test (SPT) and CPT was done as part of this investigation. The behavior of the silty sands were determined in the laboratory from monotonic and cyclic loading tests. The test results show that the effect of fines is to reduce the cone penetration resistance, but not to affect the liquefaction resistance. The steady state shear strength of the soils seems to be correlated to the cone tip resistance, however, this correlation shows a higher steady state shear strength than those back figured from case history data. The results were also used to define state parameters for both of the soils tested. The state parameter was found to be a reliable index to the liquefaction potential and further study in this area is recommended. / Ph. D.

The 2010-2011 Canterbury, New Zealand, Earthquake Sequence (CES) resulted in a liquefaction dataset of unprecedented size and quality, presenting a truly unique opportunity to assess and improve the efficacy of liquefaction-analytics in the field. Towards this end, the study presented herein develops and analyzes a database of 10,000 high-quality liquefaction case histories resulting from the CES. The objectives of these analyses are varied, but underlying each is the desire to more accurately assess liquefaction hazard for civil infrastructure (i.e., to predict both the occurrence and damage-potential of soil liquefaction). Major contributions from this work include, but are not limited to: (1) the Liquefaction Potential Index (LPI), the state-of-practice framework for assessing liquefaction hazard, is shown to produce erroneous predictions for a significant percentage of the assessed case histories; (2) the cause of poor predictions is rigorously investigated and specific shortcomings of the LPI framework are identified; (3) based on the limitations identified, and using insights from historical data, a revised liquefaction hazard framework is developed; and (4) the revised framework is shown to assess liquefaction hazard more efficiently relative to both LPI and a competing alternative framework newly proposed in the literature. Ultimately, significant room for improvement remains with respect to accurate assessment of liquefaction hazard. The findings presented in this dissertation thus form the basis for future development of a further-improved framework. Moreover, a methodology is proposed by which improvements can be measured in a standardized and objective manner. / Ph. D. / Soil liquefaction is a common cause of ground failure during earthquakes and is directly responsible for tremendous damage to civil infrastructure. Manifestations of liquefaction include the occurrence of sand blows and lateral spread failures, settlement and tilting of structures, cracking of pavements, and failure of buried lifelines due to flotation or differential settlements, among others. These effects were vividly displayed during the 2010-2011 Canterbury, New Zealand, Earthquake Sequence (CES), which resulted in a liquefaction dataset of unprecedented size and quality, presenting a truly unique opportunity to advance the science of liquefaction hazard. Towards this end, the study presented herein develops and analyzes a database of 10,000 high-quality liquefaction case histories resulting from the CES. The objectives of these analyses are varied, but underlying each is the desire to more accurately assess liquefaction hazard for civil infrastructure (i.e., to predict both the occurrence and damage-potential of soil liquefaction). Major contributions from this work include, but are not limited to: (1) the Liquefaction Potential Index (LPI), the state-of-practice framework for assessing liquefaction hazard, is shown to produce erroneous predictions for a significant percentage of the assessed case histories; (2) the cause of poor predictions is rigorously investigated and specific shortcomings of the LPI framework are identified; (3) based on the limitations identified, and using insights from historical data, a revised liquefaction hazard framework is developed; and (4) the revised framework is shown to assess liquefaction hazard more efficiently relative to both LPI and a competing alternative framework newly proposed in the literature. Ultimately, significant room for improvement remains with respect to accurate assessment of liquefaction hazard. The findings presented in this dissertation thus form the basis for future development of a further-improved framework.

The hydrogenation of coal to produce petroleum and petroleum products has been an accomplished fact for several years. The investigation in the United states has been carried to the point of constructing a full-scale plant to attempt to put the process on a commercial production basis. The volatile matter and fixed carbo of a coal are the constituents which enter into the hydrogenation reaction. The volatile matter is considered to be mostly unsaturated aromatic compounds which are readily hydrogenated. Midlothian coal contains 33 per cent volatile matter, as compared with 10 to 20 per cent in higher grade coals, and for this reason this coal was selected for this investigation. The purpose of this investigation was to determine the effect of particle size, initial hydrogen pressure from 1200 to 1800 pound per square inch gage, recycled vehicles and time of reaction on the per cent liquefaction that could be obtained. A parr high pressure hydrogenation bomb with auxiliary heating and agitating apparatus was used in this investigation. The degree of liquefaction was determined by comparison of the weight of the residual coal after hydrogenation with the weight of the original coal sample. The basic assumption of the investigation was that any loss in weight of the coal was due to liquefaction of the coal, and the products lost to the atmosphere in the gases were not considered. The reactants placed in the bomb were Midlothian coal, the vehicle tetralin (or recycled tetralin or tar residue from previous tests), stannous sulfide catalyst, and hydrogen. A series of tests was made to determine the effect of pressure, particle size, recycled tetralin as the vehicle, tar residue from previous tests as the vehicle, and time on the hydrogenation reaction. The pressure range used was from 1200 to 1800 pounds per square inch gage; the temperature was used 385°C; the time of reaction was varied from one to eight hours, the catalyst used was always equal to one per cent by the weight of the coal sample; and the vehicle to coal ratio was always 3.8;1 based on the weight of the coal. A coal particle size in the range of 139-104 microns in diameter, or passed through a 100-mesh screen, but retained on a 140-mesh screen gave a maximum liquefaction of 85 per cent. An initial hydrogen pressure of 1800 pounds per square inch gage gave a maximum liquefaction of 89.5 per cent. A reaction time of three hours gave a maximum liquefaction of 88 per cent. These percentages agree closely with the maximum of 92 per cent obtained by the U.S. Bureau of Mines in hydrogenation research⁽¹¹⁶⁾. Further findings were that the use of recycled tetralin as the vehicle had no effect on the per cent liquefaction obtained, but that the use as the vehicle of the tar fractions of the products from previous tests decreased the per cent liquefaction of the coal from 85 per cent to 70 per cent based on the weight of the coal. / M.S.

This study was designed to evaluate the ability of vertical drains to prevent liquefaction and limit associated settlement. Drain performance was investigated using full-scale tests with vertical drains in liquefiable sand using a laminar shear box with acceleration time histories applied at the base. Performance of the sand box with drains in these tests was compared with performance of the sane box without drains in previous tests. The test data was also used to create case histories which can be used for further research and calibration of computer models. Although some investigations regarding vertical drains have been performed with centrifuge tests, no full-scale drain installation had been tested previously. Two drain geometries were investigated, first with drains spaced at 4 feet and second with drains spaced at 3 feet, to determine the effect of spacing on drain effectiveness.Sand was hydraulically placed at a relative density of about 40%. Sensors to monitor pore water pressure, settlement, lateral displacement, and acceleration were placed in the laminar shear box. Three rounds of testing were performed with each drain configuration. Each round consisted of three tests, with peak sinusoidal acceleration levels of 0.05g, 0.1g, and 0.2g respectively, with 15 sinusoidal cycles in each case. A cone penetration test sounding was performed between each round as well as before and after testing to characterize the soil properties for each round.Prefabricated drains were effective at reducing excess pore pressure generation during shaking and increasing the rate of dissipation immediately following the shaking. Liquefaction induced settlement was typically reduced by about 50% relative to tests without drains. These results are in good agreement with results from previous centrifuge testing. Drains spaced closer together reduced the excess pore pressure that generated during shaking and increased the rate of pore pressure dissipation relative to tests with drains spaced further apart, but post-liquefaction settlements were similar. As the soil became denser, settlement decreased significantly, as did the time for pore pressures to dissipate.

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.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22759号 / 工博第4758号 / 新制||工||1744(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 三村 衛, 教授 渦岡 良介, 准教授 肥後 陽介 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Soil liquefaction can cause devastating damage and loss and is a serious concern in civil engineering practice. One method for evaluating liquefaction triggering potential is a risk-targeted probabilistic approach that has been shown to provide more consistent and accurate estimates of liquefaction risk than traditional methods. This approach is a “performance-based” procedure which is based off of the performance-based earthquake engineering (PBEE) framework developed by the Pacific Earthquake Engineering Research (PEER) Center. Unfortunately, due to its complexity, performance-based liquefaction assessment is not often used in engineering practice. However, previous researchers have developed a simplified performance-based procedure which incorporates the accuracy and benefits of a full performance-based procedure while maintaining a more simplistic and user-friendly approach. Until now, these simplified performance-based procedures have only been available for the SPT (Standard Penetration Test). With the increasing popularity of the CPT (Cone Penetration Test), a simplified procedure is needed for CPT-based liquefaction assessment. This thesis presents the derivation of a simplified performance-based procedure for evaluating liquefaction triggering using the Ku et al. (2012) and Boulanger and Idriss (2014) models. The validation study compares the results of the simplified and full performance-based procedures. The comparison study compares the accuracy of the simplified performance-based and traditional pseudo-probabilistic procedures. These studies show that the simplified performance-based procedure provides a better and more consistent approximation of the full performance-based procedure than traditional methods. This thesis also details the development of the liquefaction loading maps which are an integral part of the simplified method.

The presence of silt and clay particles has long been thought to affect the behavior of a sand under cyclic loading. Unfortunately, a review of studies published in the literature reveals that no clear conclusions can be drawn as to how altering fines content and plasticity actually affects the liquefaction resistance of a sand. In fact, the literature contains what appears to be contradictory evidence. There is a need to clarify the effects of fines content and plasticity on the liquefaction resistance of sandy soils, and to determine methods for accounting for these effects in engineering practice. In order to help answer these questions, a program of research in the form of a laboratory parametric study intended to clarify the effects which varying fines content and plasticity have upon the liquefaction resistance of sandy sands was undertaken. The program of research consisted of a large number of cyclic triaxial tests performed on two sands with varying quantities of plastic and non-plastic fines. The program of research also examined the applicability of plasticity based liquefaction criteria and the effects of fines content and plasticity on pore pressure generation. Lastly, a review of how the findings of this study may affect the manner in which simplified analyses are performed in engineering practice was made. The results of the study performed are used to clarify the effects of non-plastic fines content and resolve the majority of the inconsistencies in the literature. The effects of plastic fines content and fines plasticity are shown to be different than has been previously reported. The validity of plasticity based liquefaction criteria is established, the mechanism responsible for their validity is explained, and a new simplified criteria proposed. The effects of fines content and plasticity on pore pressure generation are discussed, and several recommendations are made for implementing the findings of this study into engineering practice. / Ph. D.

Frequently, deep foundations extend through potentially liquefiable soils. When liquefaction occurs in cohesionless soils surrounding a deep foundation, the skin-friction in the liquefied layer is compromised. After cyclical forces suspend and pore pressures dissipate, effective stress rebuilds and the liquefied soil consolidates. When the settlement of the soil exceeds the downward movement of the foundation, downdrag develops. To investigate the loss and redevelopment of skin-friction, strain was measured on an instrumented micropile during a blast-induced liquefaction test in Mirabello, Italy. The soil profile where the micropile was installed consisted of clay to a depth of 6m underlain by a medium to dense sand. The 25cm diameter steel reinforced concrete micropile was bored to a depth of 17m. Pore pressure transducers were placed around the pile at various depths to observe excess pore pressure generation and dissipation. Soil strain was monitored with profilometers in a linear arrangement from the center of the 10m diameter ring of buried explosives out to a 12m radius. Immediately following the blast, liquefaction developed between 6m and 12m below ground. The liquefied layer settled 14cm (~2.4% volumetric strain) while the pile toe settled 1.24cm under elastic displacement. The static neutral plane in the pile occurred at a depth of 12m. From 6m to 12m below ground, the incremental skin-friction was 50% compared to pre-liquefaction measurements. The decrease in residual skin-friction is consistent with measurements observed by Dr. Kyle Rollins from previous full-scale tests in Vancouver, BC, Canada, Christchurch, New Zealand, and Turrel, Arkansas.