Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Kathleen M. Trauth. Includes bibliographical references.

published_or_final_version / Civil Engineering / Master / Master of Philosophy

published_or_final_version / Applied Geosciences / Master / Master of Science

This thesis investigates the mechanism of a slow moving landslide through a case study based on a full-scale field monitoring conducted in a slow moving natural slope. The slope is gentle and located within a southwest-trending valley which is about 500 meters long with an average slope angle of 17°. The slope is mainly consisted of a thin colluvium top layer and a thick completely decomposed andesite layer underneath. The slope was intersected by a natural drainage channel at its toe. Previous records indicate that the slope moved slowly during or after rainfall but there is still lack of sufficient information allowing one to fully understand the mechanism. To characterize soil properties of the slope, a detailed site investigation and laboratory tests were carried out prior to the instrumentation. The full-scale comprehensive field instrumentation had been completed at the end of 2007. The real-time monitoring system was consisted of a rain gauge, vibrating wire piezometers, moisture probes, WTDRs (water time-domain reflectometry), jet-fill tensiometers, in-place inclinometers and an automatic data acquisition system with wireless transmission ability. Field monitoring of the slope was successfully conducted for two years between 2008 and 2009. With the monitored data, spatial distribution of groundwater levels in two years was obtained. The variations of groundwater levels were analyzed with hourly rainfall; groundwater responses during selected rainfall events were also analyzed. Moisture contents and matric suctions within the shallow soils at the site were monitored and analyzed. Field measured Soil-water Characteristic Curves (SWCCs) were obtained and compared with the laboratory measured SWCCs. Variations of moisture contents measured in deep soils were also analyzed. Based on the monitored results of the hydrogeological responses; a hypothetical conceptual hydrogeological model was proposed. The subsurface deformations recorded by the inclinometers were analyzed and the deformation mode of the site was also discussed. A coupled seepage and deformation analysis was conducted based on the finite element program ABAQUS. Then, the numerical simulation results were compared with field monitored data. Consequently, the simulation results verified the hypothetical conceptual hydrogeological model. It is believed that the deformation of the slope is mainly associated with the quick rise of the groundwater table during or after the heavy rainfalls. Finally, conclusions and recommendations for future research on natural terrain landslide were given. It is hoped that the study of the slow moving slope can provide a useful reference for the future research. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Civil Engineering / Master / Master of Philosophy

published_or_final_version / abstract / toc / Applied Geosciences / Master / Master of Science

published_or_final_version / abstract / toc / Civil Engineering / Doctoral / Doctor of Philosophy

No description available.

Dwyka tillite quarries in the Province of KwaZulu-Natal have shown remarkable stable slopes faces even though some of them were quarried over 30 years ago. This can be attributed to their resistance to weathering, the high degree of joint surface roughness, the general lack of any joint infill and the limonitic staining found on most weathered joint surfaces. The latter appears to increase joint roughness. The high percentages of joints terminating within the rock mass or against other discontinuities as well as their low persistence results in a high degree of joint interlocking. These are shown to be very important factors contributing to the overall slope stability. Detailed discontinuity surveys were carried out at five different quarries located throughout the KwaZulu-Natal region. Only three of these quarries are presently being quarried. This allowed the study and comparison of joint and slope stability characteristics for both the older, more weathered rock faces and those of the recently quarried, and thus fairly unweathered rock faces. Joint orientation data from the various sites show that two to three sets of high angle joints and one low angle joint set are common. The potential of wedge and planar failure is therefore very high. The steeply dipping discontinuities also promote the potential for flexural toppling failure and this was noted in several of the quarry faces. Recognised geotechnical techniques and computer models were used to establish potential modes of failure and to estimate factors of safety. Wedge failure, at partially saturated and saturated conditions, was identified as being the main source of potential slope instability on the quarry rock faces. The quality of the rock mass of each slope was also classified according to various rock mass classification systems. The rock mass quality generally was rated as being 'fair' to 'good', meaning that slopes are partially stable to stable. The results of each rating system were also compared. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

Advances in hillslope hydrology have been numerous in the past two decades. However many of these advances have been highly site specific in nature, without identifying any means of linking processes across different spatial scales. Meaningful Prediction in Ungauged Basins (PUB) requires the understanding and observation of processes across a range of scales in order to draw out typical hydrological controls. Contempory tracer based methods of quantifying a combination of hillslope processes have identified hillslope geology as the main determinant in different catchment response types. A range of hillslope scale models have been developed in the last 20 years, using different levels of detail to simulate hillslope hydrological responses. Often the data heavy requirements of hillslope scale models make them impractical to apply at larger scales. While catchment scale models lack the ability to represent hillslope scale processes. In order to overcome this, a scale applicable model with the ability to represent hillslope and catchment dynamics is required to accurately quantify hillslope and catchment hydrological processes. This study aims to characterize typical hillslope soil type responses through inferring qualitative hillslope descriptions into a numerical catchment scale model allowing for lateral subsurface routing between adjacent soil horizons. Hydrometric and tracer observation are used to describe and quantify dominant hillslope hydrological processes. Simplifications of hillslope process descriptions are used to calibrate the model to represent the subsurface hillslope connectivity. Results show that hillslope scale hydrological process characteristics can be faithfully simulated with quaternary scale climate, land use and soils data, discriminating only between different hillslope soil types. The simplification of hillslope soils into three distinct groups allows for the further derivation of dimensionless descriptors of hillslope hydrological response using the Advection Dispersion Function. Slopes with shallower stratified soils showed rapid responses to rainfall in the soil water, while those with deeper soils and less horizontal stratification showed appreciably slower responses to rainfall, with older hillslope water dominating soil water for longer periods. This identifies soils as a dominant determinant in hillslope runoff characteristics. This allows for the characterization and ultimately a simplified classification of different hillslope soils and their response types, which is applicable at a range of scales. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.