Showing papers by "Jacques Locat published in 2014"
01 Jan 2014
TL;DR: Weak layers play a major role in the development of many large submarine landslides as discussed by the authors, and a definition of a weak layer is proposed using a geotechnical perspective: a layer (or band) consisting of sediment or rock that has strength potentially or actually sufficiently lower than that of adjacent units (strength contrast) to provide a potential focus for the developing of a surface of rupture.
Abstract: Weak layers play a major role in the development of many large submarine landslides A definition of a weak layer is proposed here using a geotechnical perspective: a layer (or band) consisting of sediment or rock that has strength potentially or actually sufficiently lower than that of adjacent units (strength contrast) to provide a potential focus for the development of a surface of rupture Such a layer or a band can follow stratigraphic horizons, but this is not a requirement From this it is proposed to define two types: inherited and induced weak layers In addition, weak layers can develop in strain softening sediments where progressive failure can generate a surface of rupture without the need to invoke the role of excess pore pressures
85 citations
01 Jan 2014
TL;DR: In this article, the authors present a survey of landslide mechanisms in sensitive clays in the northern countries of the world such as Canada, Finland, Norway, Russia, Sweden and in the US state of Alaska.
Abstract: Landslides in sensitive clays represent a major hazard in the northern countries of the world such as Canada, Finland, Norway, Russia, Sweden and in the US state of Alaska. Examples of catastrophic landslides in sensitive clays that impacted populations are numerous: e.g., Saint-Jean-Vianney in 1971 (Tavenas et al. 1971; Potvin et al. 2001), Rissa in 1979 (Gregersen 1981; L’Heureux et al. 2012), Finneidfjord in 1996 (Longva et al. 2003), Kattmarka in 2009 (Nordal et al. 2009) and St-Jude in 2010 (Locat et al. 2012). In order to respond to the societal demands, the scientific community has to expand its knowledge of landslide mechanisms in sensitive clay to assist authorities with state-of-the-art investigation techniques, hazard assessment methods, risk management schemes, mitigation measures and planning.
22 citations
01 Jan 2014
Abstract: Landslides in Eastern Canadian sensitive clay deposits are generally located along river or stream valleys. The stratigraphy of these deposits can be simplified as an impervious clay deposit between two pervious boundaries, a weathered fissured crust at the top and a coarse till layer at the bottom. The paper examines the evolution of the ground water regime as the valleys are formed by erosion and discusses the impact of the valleys formation on the requirements for slope stability analysis and determination of shear strength. A large data bank of laboratory test results are then presented and treated to arrive at a determination of the shear strength parameters based only on the preconsolidation pressure.
19 citations
01 Jan 2014
TL;DR: The relationship between activity and specific surface area of sensitive clays shows that when compared to soils from different sedimentary basins that have different mineralogy, they are characterized by a much lower activity as discussed by the authors.
Abstract: Quantitative mineralogical analyses of sediment samples from 18 sites in Quebec indicate that plagioclase is the most abundant mineral in all soils and that chlorite is generally the dominant clay mineral followed by illite and expandable clays consisting of mixed-layer clays minerals involving vermiculite. The study also illustrates how specific surface area and constitutive water content can be used to evaluate departures from average in the mineralogical composition of sensitive clays. The relationship between activity and specific surface area of sensitive clays shows that when compared to soils from different sedimentary basins that have different mineralogy, they are characterized by a much lower activity and specific surface area.
14 citations
01 Jan 2014
TL;DR: In this article, a geomorphological analysis of the Veatch slide complex is presented, indicting the presence of at least two major slides presenting different morphological characteristics and involving different type of sediments (in terms of strength and grain size).
Abstract: A geomorphological analysis of the Veatch slide complex is presented here indicting the presence of at least two major slides presenting different morphological characteristics and involving different type of sediments (in terms of strength and grain size). These slides took place after the erosion of the Veatch Canyon which had been the locus of many bank failures. It is shown that a more refined morphological analysis of similar landslide areas may lead to the definition of a greater number of slides and a greater role of channels both leading to a more complex interpretation on their mobility.
3 citations
01 Jan 2014
TL;DR: Early in the morning of April 3rd, 1980, approximately 1.15 × 106 m3 of soils from the coastal bluffs spread out over the tidal flat along the North Shore of the Jacques-Cartier Strait in the Gulf of St. Lawrence.
Abstract: Early in the morning of April 3rd, 1980, approximately 1.15 × 106 m3 of soils from the coastal bluffs spread out over the tidal flat along the North Shore of the Jacques-Cartier Strait in the Gulf of St. Lawrence. This landslide had a width of 410 m and had retrogressed back up to 110 m from the slope crest, cutting through Highway 138, 9 km west of the town of Havre-St-Pierre. In this area, the coastal bluffs are approximately 23 m high and consist, from the bottom to the top, of a thick marine sensitive clay unit from the Goldthwait Sea, overlain by 3 m of sand and 3 m of peat on top. The debris morphology has a “thumbprint-like pattern” characterized by unbroken blocks of intact clay forming elongated ridges, surrounded by a mixture of remoulded clay, sand and peat, aligned parallel to the bluff and arched in the direction of the flow. The absence of obstacles and the non-channeled character of the flow path of the Havre-St-Pierre landslide provide a good opportunity to characterize and analyze the post-failure stage of this large landslide in sensitive clays.
2 citations
01 Jun 2014
TL;DR: Amoushahi et al. as discussed by the authors presented a case study on the design of a major new regional highway along the crest of an abandoned mine in the city of Thetford Mines, Québec, Canada.
Abstract: This paper presents a review of the literature on the design of public roads in the vicinity of open-pit mines, focusing on the latter's impact on slope stability. It then presents a case study on the design of a major new regional highway along the crest of an abandoned mine in the city of Thetford Mines, Québec, Canada. The first step involved a back analysis of a recent slope failure close to the location of the planned highway in order to derive rock mass properties at the slope scale. Analyses were conducted using the Shear Strength Reduction (SSR) method coupled with finite element (FE) modeling as well as the limit equilibrium analysis (LE) method. Airborne LiDAR surveying results were used in order to calibrate and validate the models. Forward modelling was then performed to assess future slope stability. CITATION Amoushahi S, Grenon M, Locat J, Turmel D. Assessment of the influence of the slope stability conditions of an inactive open-pit mine on the design of a nearby highway. Proceedings of Geohazards 6, Kingston, Canada (June 15 – 18, 2014) This is the author’s version of the original manuscript.
2 citations