Fredlund D.G.,Golder Ltd. |
Nguyen Q.,Klohn Crippen Berger Ltd.
Advances in Transportation Geotechnics II - Proceedings of the 2nd International Conference on Transportation Geotechnics, ICTG 2012
The performance of rural highways in Saskatchewan, Canada, constructed of a thin pavement structure is largely controlled by the strength of subgrade soil. The subgrade of these highways consists of compacted unsaturated soil and its strength is a function of net normal stress and soil suction. In situ soil suctions can be measured using indirect technologies such as thermal conductivity suction, (TCS), sensors. Thirty-two thermal conductivity sensors were installed under Thin Membrane Surfaces, (TMS), at two highway locations in southern Saskatchewan, Canada. Soil suctions have been monitored at these sites for more than 10 years. The soil suction readings in the field showed a response to rainfall conditions at the test sites. Changes in soil suction on the shoulder of the road appeared to be mainly due to run-off and infiltration. Relatively constant equilibrium suctions were encountered below the pavement. Suction changes throughout the year were similar from one year to the next. The thermal conductivity TCS sensors performed well under harsh weather conditions including freeze-thaw conditions. An understanding of the soil suction and temperature change behavior of the subgrade throughout the year was obtained from the data. © 2012 Taylor & Francis Group. Source
Ind M.,Klohn Crippen Berger Ltd.
Hydrology and Water Resources Symposium 2014, HWRS 2014 - Conference Proceedings
A proposed mine development project located in the South Pacific required predictions of sediment loads and concentrations that could be discharged from site and how this varied over the life of the mine. The site location was in extremely rugged terrain with a high annual rainfall of approximately 4.7 m and also subject to cyclonic activity. There were two major sediment ponds proposed for the site to reduce sediment discharges. Total Suspended Solids (TSS) concentration was the key criterion that was required to be modelled as this was referenced back to the discharge water quality guidelines. A sediment and hydrology model was developed in Goldsim to provide daily estimates of runoff flows and TSS concentrations. A modified model of the Australian Water Balance Model (AWBM) was developed and incorporated into the Goldsim model and calibrated using recorded field data. The sedimentology module in the Goldsim model was developed based on the Revised Universal Soil Loss Equation (RUSLE). As RUSLE is an annual prediction of soil loss over a catchment, modifications were required to provide daily estimates of TSS concentrations. This was achieved by proportioning the annual R value over the year with the assumption that higher rainfall (intensity) days produced proportionally higher rainfall erosivity. Using RUSLE, a land-use type erosion vector was developed for 19 different land-use types (for example natural ground, open-pit, waste dump, etc.). For each sub-catchment (57 in total), the proportion of land-use type was calculated and then used to produce a sub-catchment erodibility vector. This vector was multiplied by the daily rainfall erosivity factor to estimate the daily soil loss from each sub-catchment. The estimated soil loss and the modelled runoff produced predictions of daily TSS concentrations. Finally a sediment settling module was used to predict the daily efficiency of the sediment ponds and hence discharged TSS concentrations. Source
Macciotta R.,University of Alberta |
Martin C.D.,University of Alberta |
Edwards T.,Canadian National Railway |
Cruden D.M.,University of Alberta |
Keegan T.,Klohn Crippen Berger Ltd.
Relationships between weather conditions and rock fall occurrences have been acknowledged in the past, but seldom have such relationships been quantified and published. Rock falls are frequent hazards along transportation corridors through mountainous terrain, and predicting hazardous rock fall periods based on weather conditions can enhance mitigation approaches. We investigate the relationship between weather conditions and rock fall occurrences along a railway section through the Canadian Cordillera. Monthly weather-rock fall trends suggest that the seasonal variation in rock fall frequency is associated with cycles of freezing and thawing during the winter months. The intensity of precipitation and freeze–thaw cycles for different time-windows was then compared against recorded rock falls on a case-by-case approach. We found that periods when 90% of rock falls occurred could be predicted by the 3-day antecedent precipitation and freeze–thaw cycles. Some rock falls not predicted by this 3-day antecedent approach occurred during the first two weeks of spring thaw. These findings are used to propose a rock fall hazard chart, based on readily available weather data, to aid railway operators in their decision-making regarding safe operations. © 2015 Taylor & Francis. Source
Sturzenegger M.,Klohn Crippen Berger Ltd. |
Stead D.,Simon Fraser University |
Gosse J.,Dalhousie University |
Ward B.,Simon Fraser University |
Froese C.,Alberta Geological Survey
This paper presents the results of a combined study, using cosmogenic 36Cl exposure dating and terrestrial digital photogrammetry of the Palliser Rockslide located in the southeastern Canadian Rocky Mountains. This site is particularly well-suited to demonstrate how this multi-disciplinary approach can be used to differentiate distinct rocksliding events, estimate their volume, and establish their chronology and recurrence interval. Observations suggest that rocksliding has been ongoing since the late Pleistocene deglaciation. Two major rockslide events have been dated at 10.0 ± 1.2 kyr and 7.7 ± 0.8 kyr before present, with failure volumes of 40 and 8 Mm3, respectively. The results have important implications concerning our understanding of the temporal distribution of paraglacial rockslides and rock avalanches; they provide a better understanding of the volumes and failure mechanisms of recurrent failure events; and they represent the first absolute ages of a prehistoric high-magnitude event in the Canadian Rocky Mountains. © 2014 Springer-Verlag Berlin Heidelberg Source
Thavaraj T.,Klohn Crippen Berger Ltd. |
Finn W.D.L.,University of British Columbia |
Wu G.,BC Hydro
Geotechnical and Geological Engineering
A quasi-3D continuum method is presented for the dynamic nonlinear effective stress analysis of pile foundation under earthquake excitation. The method was validated using data from centrifuge tests on single piles and pile groups in liquefiable soils conducted at the University of California at Davis. Some results from this validation studies are presented. The API approach to pile response using p-y curves was evaluated using the quasi-3D method and the results from simulated earthquake tests on a model pile in a centrifuge. The recommended API stiffnesses appear to be much too high for seismic response analysis under strong shaking, but give very good estimates of elastic response. © Springer Science+Business Media B.V. 2010. Source