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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
Landslides | Year: 2014

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

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
Georisk | Year: 2015

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.

Thavaraj T.,Klohn Crippen Berger Ltd. | Finn W.D.L.,University of British Columbia | Wu G.,BC Hydro
Geotechnical and Geological Engineering | Year: 2010

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.

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 | Year: 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.

Ind M.,Klohn Crippen Berger Ltd
Hydrology and Water Resources Symposium 2014, HWRS 2014 - Conference Proceedings | Year: 2014

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.

Jefferies M.,Golder Associates | Shuttle D.,Klohn Crippen Berger Ltd
Geotechnique | Year: 2011

Stress dilatancy provides a fundamental flow rule for constitutive models and several variations on the framework have similar operational performance. However, regardless of idealisation adopted for stress dilatancy, the scaling coefficient evolves and only attains the critical friction ratio at large strain. The scaling coefficient also depends on the proportion of intermediate principal stress. Data on stress dilatancy in triaxial compression and plane strain are reviewed. Based on these data, a simple function is proposed for stress-dilatancy scaling using an operational friction ratio Mi based on workconjugate stress and strain invariants. The function is calibrated to soil properties measured in conventional drained triaxial tests (about three, suitably chosen, tests are needed in addition to those used to define the critical state locus) and predicts strength in plane strain to an accuracy of̃ 60.03 at 80% confidence for the Brasted and Changi sands considered (i.e. about 6 3% of typical peak strength). The proposed function is suitable for any soil constitutive model that includes a critical state line and which invokes stress dilatancy.

Slack C.H.,Klohn Crippen Berger Ltd. | Mack D.L.,Klohn Crippen Berger Ltd. | Nilson A.,Alberta Transportation
Proceedings, Annual Conference - Canadian Society for Civil Engineering | Year: 2012

The Western Headworks system, of which the Calgary Bow River Weir is a part, was originally constructed by the Canadian Pacific Railroad in 1908 to divert water from the Bow River for irrigated agriculture in the semi-arid region east of Calgary. The "Calgary Weir" represented the only barrier to boaters and fish passage in the 100 km section of the Bow River between the Bearspaw Dam and the Carseland Weir. The ogee-shaped weir included a submerged, concave-shaped bucket deflector which created rollers (bucket roller and ground roller) to dissipate energy and prevent downstream scour. These rollers have claimed over 20 lives; consequently, the weir was infamously labelled the "Drowning Machine" as a testament to the unforgiving danger it posed. The Calgary Bow River Weir Project's primary purpose was to eliminate the extreme drowning hazard and enable passage for non-motorized boats and fish while maintaining water diversions from the Bow River. To achieve this, eight pools and eleven rapids were constructed to change the hydraulic conditions downstream of the weir from the existing concentrated circulating flow pattern to an extended linear pattern. The project creates an amenity for canoeists, kayakers, bird watchers, floaters, and educators. Construction with the Bow River flowing through the project was challenging. Utilizing innovative construction materials and techniques (boulders and macro-fibre reinforced concrete) provided the aesthetic character that was required, greatly increased the pace of construction, and reduced the project cost. The project was constructed on schedule and under budget at a cost of $16.5 million.

Lo R.C.,Klohn Crippen Berger Ltd.
Geotechnical Special Publication | Year: 2013

This paper reviews the geotechnical impact of the 2008 Wenchuan Earthquake gleaned from references obtained through internet and other sources. It briefly describes the seismo-tectonic and geological setting of the seismic source region, and discusses various geotechnical aspects of the event. Strong ground motions and fault displacements in a setting of steep mountainous terrains trigger many failures of natural slopes and man-made structures. Coseismic hazards include landslides, debris flows and formation of landslide dams. These ground failures not only increase earthquake damage and hamper rescue and recovery effort, but also generate a secondary flood hazard due to potential breach of landslide dams. The epicentral region has also many high water-storage embankment dams, which seem to fare quite well. Finally, the event has set the stage for latent geological hazard caused by earthquake-weakened slopes and/or metastable landslide/debris-flow deposits. This hazard would materialize either in an aftershock or heavy storm/snow-melt event. © 2013 American Society of Civil Engineers.

Sturzenegger M.,Klohn Crippen Berger Ltd. | Stead D.,Simon Fraser University
Geomorphology | Year: 2012

This paper presents the results of an investigation of the prehistoric Palliser Rockslide, Rocky Mountains, Canada. Conventional aerial photograph interpretation and field mapping are complemented by terrestrial digital photogrammetry. These techniques allow quantification of the rockslide debris volume and reconstruction of the pre-slide topography. It has been estimated that the volume of rock involved in the most recent large rockslide is 8Mm 3. Terrestrial digital photogrammetry is used in the characterization of the failure surface morphology, which is subdivided into four types of step-path geometry comprising both pre-existing discontinuities and intact rock fractures. Incorporation of these data into various rock slope stability numerical modeling methods highlights a complex failure mechanism, which includes sliding along a large scale curved failure surface, intact rock bridge fracturing and lateral confinement. A preliminary quantification of the contribution of intact rock bridges to the shear strength of the failure surface is presented in terms of the apparent cohesion, apparent tensile strength and cumulative length of the intact rock segments. © 2011 Elsevier B.V.

Thavaraj T.,Klohn Crippen Berger Ltd. | Stevenson G.,Klohn Crippen Berger Ltd. | Siu D.,BC Hydro
Geotechnical Special Publication | Year: 2016

This paper presents the seismic assessment of a central core embankment dam partially founded on relatively weak, low plastic fine-grained soils. Characterization of low plastic fine-grained soils, especially their cyclic and post-cyclic behavior was critical in assessing the seismic performance of the dam. A site investigation and laboratory testing program was undertaken to characterize the low plastic fine-grained soils and their behavior under the cyclic loading. An effective stress based constitutive model UBCSAND, developed at the University of British Columbia, Canada and implemented in the computer program FLAC, was shown to be able to capture the characteristic cyclic behavior observed in the laboratory cyclic direct simple shear tests. Seismic deformation analyses using the model showed that, although the low plastic fine grained soils will not behave like loose sand, it can still cause significant displacements due to accumulation of strains during cyclic loading. © ASCE.

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