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Rainfall induced granular flow slides pose a significant risk in many areas of the world. These failures, characterized by the sudden release of material in a fluid-like manner, are the result of static liquefaction occurring in these slopes. The static liquefaction phenomenon has been linked to instability. Instability behaviour is primarily studied under undrained triaxial conditions, and although many instability theories have therefore been defined in this stress space, these have been shown to also extend into plane strain conditions. In order to further investigate this behaviour under these stress conditions, Wolinsky et al. (2013) developed a tilt-table soil box for use in a geotechnical centrifuge to analyze instability in infinite slope soil models. This testing apparatus has been used to simulate instability in plane strain under both dry and saturated soil conditions. Stress-controlled experiments were performed on dry infinite slope soil models to investigate the effects of both void ratio and effective stress on instability behaviour. By performing these tests dry, this test apparatus provides the ability to decouple the triggers of instability from the corresponding response in pore pressure and the consequences. The results of this testing confirmed that the instability line angle is a function of both void ratio and effective stress. As the void ratio decreases and effective stress in the soil model increases, the resulting instability line angle will increase. This testing also demonstrated typical stress-dilatancy behaviour in these infinite slope models, characterized by contractive response in loose soils and dilative response in dense soil subject to increasing shear stress. Secondly, this testing apparatus was used to investigate the effects of seepage force on instability behaviour in granular slopes through the introduction of groundwater seepage in the form of a rising groundwater level. Although the results illustrated shear and volumetric response to these increased pore water pressures, these were not significant enough to initiate instability and the resulting pore water response leading to failure. It has been determined that this apparatus must be further adapted to dissipate the matric suctions developed above the water table during groundwater rise. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-12-03 21:06:56.806

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A digital modulation method using Chirp-Slope Keying (CSK) is developed for coherent underwater acoustic communications. Effective signal detection is a critical stage in the implementation of any communications system; we will see that CSK solves some significant challenges to reliable detection. This thesis is primarily based on analyzing the effectiveness of CSK through simulations using Matlab's Simulink for underwater communications. The procedure begins with modulating a chirp's slope by random binary data with a linear-down-slope chirp representing a 0, and a linear-up-slope chirp representing a 1. Each received symbol is demodulated by multiplying it with the exact linear-up-slope chirp and then integrating over a whole period (i.e., integrate and dump). This slope-detection technique reduces the need for the extensive recognition of the magnitude and/or the frequencies of the signal. Simulations demonstrate that CSK offers sturdy performance in the modeled ocean environment, even at very low signal-to-noise ratio (SNR). CSK is first tested using the fundamental communication channel, Additive White Gaussian Noise (AWGN) channel. Simulation results show excellent BER vs. SNR performance, implying CSK is a promising method. Further extensive analysis and simulations are performed to evaluate the quality of CSK in more realistic channels including Rayleigh amplitude fading channel and multipath.

Abstract The high Drakensberg of southern Africa has received considerable geomorphological interest during recent decades. In particular, there has been an ongoing debate concerning the accuracy of landform interpretations which propagate past glaciation and permafrost. This research examines the macro and micro-sedimentology of various deposits found in eastern Lesotho and compares them with possible geomorphological process origins such as debris flows, debris avalanches, mudflows, mudslides, landslides, solifluction deposits, rock glaciers, pronival ramparts, glacial moraines and fluvial deposits. The results support the contention that four of the deposits are moraines, formed by small glaciers, and one is a debris flow which was initiated by a small glacier. However, two further deposits indicate that localities in close proximity to the linear deposits experienced mass wasting, associated with past periglacial conditions. With the assistance of applying glacier reconstruction methods, modelling hillshade, the provision of new palaeoclimatic extrapolations, and correlation of deposits with contemporary snow patch distribution, it is demonstrated that the valley slope deposits are determined by a past climate that was within the glacial/periglacial equilibrium zone, and was influenced by specific topographic and associated micro-climatic thresholds. It is shown that macro-topographic factors (e.g. slope gradient, aspect etc) and summit altitude are critical factors determining whether slopes were influenced by periglacial (mass wasting) or glacial processes (small niche/cirque glaciers) in adjacent valleys.

The coupled effect of using geosynthetic reinforcement and randomly distributed fibers on the stability of slopes was evaluated using finite element modeling and limit equilibrium methods by analyzing a case study in Oslo, Norway. The main objective was to simulate the failure condition of the original slope and quantify the improved stability of a hypothetical reinforced slope constructed with geosynthetic layers and distributed discrete fibers. The stability of the slope was evaluated in both the short-term condition with its' undrained shear strength parameters, and the long-term drained condition. Results indicate that the combination of the techniques was found to have a possible increase of about 40% in the short-term condition and about 60% in the long-term condition of the factor safety associated with the slope. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

This project addresses the topic of evaluating water movement inside a hillslope using a combination of conventional and advanced geophysical techniques. While slope dynamics have been widely studied, ground water movement in hills is still poorly understood. A combination of piezometers, ground-penetrating radar (GPR), and electrical resistivity (ER) surveys were used in an effort to monitor fluctuations in the subsurface water level in a reengineered slope near Keokuk, Iowa. This information, integrated with rainfall data, formed a picture of rainfall-groundwater response dynamics. There were two hypotheses: 1) that the depth and fluctuation of the water table could be accurately sensed using a combination of monitoring wells, ground-penetrating radar and resistivity surveys; and 2) that the integration of data from the instrumentation array and the geophysical surveys would enable the characterization of water movement in the slope in response to rainfall events. This project also sought to evaluate the utility and limitations of using these techniques in landslide and hydrology studies, advance our understanding of hillslope hydrology, and improve our capacity to better determine when slope failure may occur. Results from monitoring wells, stratigraphy, and resistivity surveys at the study site indicated the presence of a buried swale, channelizing subsurface storm flow and creating variations in groundwater. Although there was some success in defining hydrologic characteristics and response of the slope using this integrated approach, it was determined that GPR was ultimately not well suited to this site. However, the use of GPR as part of an integrated approach to study hillslope hydrology still appears to hold potential, and future work to further evaluate the applicability and potential of this approach would be warranted.

This study investigates the hydrodynamic variations along the Gao-ping Submarine Canyon influence by the topography effects. The data used in this study were collected from two cruises of field observations using research vessel OR3. Instruments applied include sb-ADCP¡Bbm-ADCP¡Bmoored-ADCP¡BCTD and several vertical strings of temperature loggers. Parameters recorded include flow velocities, water temperature and tidal elevation. The analysis method is enlightenment by the case study in the Monterey Canyon of California. The results show that (1) the current speed in the lower layer is faster than that of upper layer, which is explained due to v-shape of topography and bottom-trapped effect of internal tide. This result is consistent with previous studies. (2) In flood tide, the currents flowed into the Canyon from deep water to shallower. The baroclinic kinetic energy decreased to 0.2 at the turning point of canyon axis at 230m water, whichwas caused mainly by bottom friction. On the other hand, the baroclinic kinetic energy increased to 0.47 at 250m water in ebb tide when there was less influence of bottom friction. (3) In comparison the effects of bottom slope and area of cross section of the canyon, the baroclinic kinetic energy dissipation was mainly occurred at up slope flow during the flood tide. The change of the canyon width had less influence. During the ebb, the baroclinic kinetic energy was mainly due to the change of canyon width in the region shallower then the 230m of the second turning of the canyon. (4) The loss of kinetic energy during flooding up slope current can be verified by the changes of water mass temperature. Cold bottom was raised to upper layer when there was large drop of kinetic energy. There was likely a conversion of kinetic energy to potential energy. No upwelled cold water detected during ebb current with increase of kinetic energy.