A research program was undertaken to quantify the effect of flow induced erosion on the stability of natural river banks along the Red River in Winnipeg, Manitoba. The study correlated the percent decrease in factor of safety to intensity of river flow and duration. Two methods to quantify flow induced erosion were assessed, the first method based on observed erosion and the second on theoretically calculated erosion. The first method involved aligning annual historical river bank cross-sections and measuring the distance between cross-sections to represent the erosion induced from the flow year between successive cross-sections. Due to the fact there are no sites along the Red River regularly surveyed, the analysis did not provide for a correlation between erosion from a specific flow event to percent decrease in factor of safety. The second part involved the use of theoretical equations to quantify erosion given the river elevation of a specific flow year. The study showed a 1% to 8% decrease in factor of safety from low to high intensity flows and as high as 14.5% for high intensity flows of long duration. Additionally, the evolutionary stability of the riverbank was generated showing the percent decrease each year in factor of safety due to erosion and the years during which failure occurs. The results correlated well to the previous analysis showing a 1% to 5% decrease for low to high intensity flows respectively and as high as 10% for high intensities of long duration. / October 2007

In this study the stabili ty and stress distribution of anisotropic jointed rock slopes under external loading were examined. The influence of joint orientation and mechanical characteristics on the engineering behaviour of jointed rock slopes were included in the investigation. A total of four physical models were developed by using blocks of light-weight concrete and gypsum mortar to simulate intact rocks and joints respectively. The models were built within a confining frame such that plane strain conditions were maintained throughout the experiments. The stress-strain relationship and the strength of the model blocks were determined from laboratory tests. An empirical equation was established to represent the strength envelope of the model material and rocks in general. The normal and shear properties of the model rock JOints were examined, and were described by mathematical expressions in order to facilitate the numerical studies. Results from the physical modelling studies showed that localised failure regions were induced and three types of failure modes were identified. The stability and stress distribution wi thin the models were found to be significantly influenced by the properties and system of the jointing. Two computer programs were developed based on the Finite Element Method and Coupled Finite-Boundary Element Method in order to simulate the behaviour of jointed rock masses and assessments of their application were made in comparison with the physical modelling results. A special finite joint element was developed to incorporate the non-linearity and anisotropy behaviour of rock joints. The finite element program was successfully executed and gave reasonable results in which the principal stress distributions were generally in agreement with those obtained from the physical models. The finite-boundary element program on the other hand introduced boundary incompatibility in the system and therefore led to divergency.

A research program was undertaken to quantify the effect of flow induced erosion on the stability of natural river banks along the Red River in Winnipeg, Manitoba. The study correlated the percent decrease in factor of safety to intensity of river flow and duration. Two methods to quantify flow induced erosion were assessed, the first method based on observed erosion and the second on theoretically calculated erosion. The first method involved aligning annual historical river bank cross-sections and measuring the distance between cross-sections to represent the erosion induced from the flow year between successive cross-sections. Due to the fact there are no sites along the Red River regularly surveyed, the analysis did not provide for a correlation between erosion from a specific flow event to percent decrease in factor of safety. The second part involved the use of theoretical equations to quantify erosion given the river elevation of a specific flow year. The study showed a 1% to 8% decrease in factor of safety from low to high intensity flows and as high as 14.5% for high intensity flows of long duration. Additionally, the evolutionary stability of the riverbank was generated showing the percent decrease each year in factor of safety due to erosion and the years during which failure occurs. The results correlated well to the previous analysis showing a 1% to 5% decrease for low to high intensity flows respectively and as high as 10% for high intensities of long duration.

A research program was undertaken to quantify the effect of flow induced erosion on the stability of natural river banks along the Red River in Winnipeg, Manitoba. The study correlated the percent decrease in factor of safety to intensity of river flow and duration. Two methods to quantify flow induced erosion were assessed, the first method based on observed erosion and the second on theoretically calculated erosion. The first method involved aligning annual historical river bank cross-sections and measuring the distance between cross-sections to represent the erosion induced from the flow year between successive cross-sections. Due to the fact there are no sites along the Red River regularly surveyed, the analysis did not provide for a correlation between erosion from a specific flow event to percent decrease in factor of safety. The second part involved the use of theoretical equations to quantify erosion given the river elevation of a specific flow year. The study showed a 1% to 8% decrease in factor of safety from low to high intensity flows and as high as 14.5% for high intensity flows of long duration. Additionally, the evolutionary stability of the riverbank was generated showing the percent decrease each year in factor of safety due to erosion and the years during which failure occurs. The results correlated well to the previous analysis showing a 1% to 5% decrease for low to high intensity flows respectively and as high as 10% for high intensities of long duration.

No description available.

No description available.

No description available.

This study has demonstrated that the phenomenon of acoustic emission can be used to detect and monitor first time deformation characteristics in stiff, heavily-overconsolidated clay soils. The results from two field studies are presented and discussed with the aim of identifying the mechanisms responsible for the generation of acoustic emission. The first study, conducted at the Building Research Establishment's test site at Cowden (Humberside), was a section of cliff, naturally eroded by sea action. The second study, conducted in a 'moth-balled' brick-pit in Arlesey (Bedfordshire), was a large scale test in which instability was induced in a cut slope (in the Gault Clay) by cutting away at the toe. A number of different designs of wave guide were installed at both sites in order to determine the relative performance of each and, also, to provide further insight into the generation mechanisms. Some consideration has also been given to the effect of alternative data processing techniques. The results obtained indicate that the active wave guide model is the more appropriate in explaining the occurrence of acoustic emission and this finding is supported by the results of laboratory tests designed to replicate the perceived role of the wave guide in the field. In itself, identification of the generation mechanism is a result but, more importantly, understanding of the mechanics enables the design of monitoring systems which are suited to particular geotechnical conditions. Some comparison is also made between acoustic emission and standard methods of deformation monitoring. It is observed that acoustic emission can detect and clearly indicate disturbances at the same time as standard methods record such small magnitudes of movement as to be indistinguishable from instrument error. Additionally, a number of triaxial shear tests were conducted on a selection of soils which illustrates that different soils do exhibit different acoustic characteristics. Finally, this study demonstrates the feasibility of envelope processing using analogue to digital signal conversion both in the field and laboratory. Four published papers pertaining to work described within this thesis are appended.

No description available.

[pt] No presente trabalho realizou-se a implementação de um programa de análise de estabilidade de encostas incluindo aspectos não convencionais tais como ruptura progressiva, anisotropia de resistência e considerações de não saturação do solo. O método generalizado das cunhas de Sarma 79 foi utilizado para consideração destes aspectos, tomando-o como base para o desenvolvimento desta nova ferramenta analítica, aplicável ao estudo da estabilidade de encostas em solos residuais não saturados. A simulação dos efeitos da ruptura progressiva foi realizada a partir do trabalho desenvolvido por Huaman (1991), na Puc-Rio. O programa desenvolvido apresenta rotinas de geração automática da superfície de ruptura e do conjunto das inclinações críticas das interfaces das cunhas, além de diversas formas de consideração das poropressões, incluindo a possibilidade de ocorrência da sucção. Além do critério de ruptura de Mohr-Coulomb foi implementado um modelo anisotrópico de resistência que permite a representação de uma anisotropia que pode existir, mesmo em solos homogêneos, de acordo com a metodologia apresentada por Bicalho (1991). Os resultados obtidos através das rotinas implementadas foram comparados com os existentes na literatura, resultantes de análises realizadas por outros métodos de análise, comprovando desta forma, a eficiência do programa desenvolvido neste trabalho. / [en] Here a computer software including non traditional issues as progressive failure, anisotropy and unsaturated soil for general slope stability analysis is implemented.The generalized method Sarma 79 was the base to consider these non-traditional issues on this new tool for the slope stability study of unsaturated residual soils.The progressive failure simulation effects were carried out following Huaman (1991) in his work at PUC-Rio, and aspects of anisotropy followed the work by Bicalho (1991). The computer program has subroutines that automatically construct the critical failure surfaces of any shape and the critical inclination of wedges set besides several ways of considering water pressures and suction ocurring. The strength anisotropy model allows to consider micro structural anisotropy within the context of the Mohr- Coulomb failure criterion. The results from the developed tool were compared with ones published on the current literature.