Landslides Clague, John J; Stead, Douglas
08/2012
eBook
Landslides have geological causes but can be triggered by natural processes (rainfall, snowmelt, erosion and earthquakes) or by human actions such as agriculture and construction. Research aimed at ...better understanding slope stability and failure has accelerated in recent years, accompanied by basic field research and numerical modeling of slope failure processes, mechanisms of debris movement, and landslide causes and triggers. Written by 75 world-leading researchers and practitioners, this book provides a state-of-the-art summary of landslide science. It features both field geology and engineering approaches, as well as modeling of slope failure and run-out using a variety of numerical codes. It is illustrated with international case studies integrating geological, geotechnical and remote sensing studies and includes recent slope investigations in North America, Europe and Asia. This is an essential reference for researchers and graduate students in geomorphology, engineering geology, geotechnical engineering and geophysics, as well as professionals in natural hazard analysis.
This book is designed to assist the civil and geotechnical engineer, geomorphologist, forester, landscape architect or ecologist in choosing ecotechnological solutions for slopes that are prone to a ...variety of mass movements e.g. shallow failure or erosion. Within this book, the ‘engineer’ is used in the global sense to encompass all planners, designers, etc. who are involved in the stabilisation of slopes. We review the types of problematic slopes that may occur and describe briefly the nature of mass movements and the causes of these movements. In this book, we focus on the use of vegetation to stabilize soil on slopes prone to mass movements. Before a plant can be chosen for a particular function, its physical and hydrological properties must be determined, thus the root architecture of grasses, shrubs and trees are described and the soil hydrological and mechanical factors which influence vegetation are discussed. Depending on the use of the slope, the engineer may wish to ascertain either the stability of the slope or the mechanical stability of the vegetation or both, therefore slope stability analysis methods are reviewed and the contribution the vegetation has to the stability of the slope are explained. Models to assess the mechanical stability of vegetation are reviewed. This book also introduces new ecotechnological methods for stabilising active rockfalls on steep slopes and slopes that are prone to soil erosion following wild fires, as well as providing user friendly information on traditional ground bio-engineering techniques and tables of plants suitable for different functions. Case studies where ground bio- and eco-engineering measures have been put into practice are also discussed.
Characterises the mechanical properties of Pinus radiata D.Don roots (the common tree species used for afforestation in New Zealand),including root tensile strength and root reinforcement at the ...hillslope scale, by means of field pullout tests and by measuring the root distribution at 360 degrees around trees. Quantifies the minimum representative sampling size for the reliability of engineering applications for slope stability calculations. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Transportation corridors such as roadways are often subjected to both natural
instability and cut-slope failures, with substantial physical damage to the
road infrastructure and threats to the ...circulating vehicles and passengers. In
the early 2000s, the Gipuzkoa Provincial Council of the Basque Country in
Spain noted the need for assessing the risk related to the geotechnical
hazards of its road network, in order to assess and monitor their safety for
road users. The quantitative risk assessment (QRA) was selected as a tool
for comparing the risk of different hazards on an objective basis. Few
examples of multi-hazard risk assessment along transportation corridors
exist. The methodology presented here consists of the calculation of risk, in
terms of probability of failure and its respective consequences, and it was
applied to 84 selected points of risk (PoR) over the entire road network
managed by the Gipuzkoa Provincial Council. The types of encountered slope
instabilities that are examined are rockfalls, retaining-wall failures, and
slow-moving landslides. The proposed methodology includes the calculation of
the probability of failure for each hazard based on an extensive collection
of field data, and its association with the expected consequences.
Instrumentation data from load cells and inclinometers were used for the anchored walls
and the slow-moving landslides, respectively. The expected road damage was
assessed for each hazard level in terms of a fixed unit cost (UC). The results
indicate that the risk can be comparable for the different hazards. A total of 21 % of
the PoR in the study area were found to be of very high risk.
A large landslide (40 × 10
6
m
3
) was reactivated on the left bank of Canelles reservoir, Spain. The instability was made evident after a considerable reduction of the reservoir level. The drawdown ...took place during the summer of 2006 after several years of high water levels. The drawdown velocity reached values between 0.5 and 1.2 m/day (registered at low elevations). The paper reports the geological and geotechnical investigations performed to define the movement. The geometry of the slip surface was established from the detailed analysis of the continuous cores recovered in deep borings and from limited information provided by inclinometers. Deep piezometric records provided also valuable information on the pore water pressure in the vicinity of the failure surface. These data allowed validating a flow–deformation coupled calculation model, which takes into account the changes in water level that occurred 4 years previous to the failure as well as the average rainfall. The analysis indicates that the most likely reason for the instability is the rapid drawdown that took place during the summer of 2006. The potential sudden acceleration of the slide is also analysed in the paper introducing coupled thermal hydraulic and mechanical effects that may develop at the basal shearing surface of the sliding mass. The results indicate that the slide velocity may reach values around 16 m/s when displacement reaches 250 m.
Although the impervious layer under a hydraulic structure is rarely flat, the effect of the impervious layer’s slope, under the hydraulic structure, on seepage characteristics has not been studied to ...date. Therefore, this study investigated the effect of the downhill and uphill impervious layer’s slope (downhill/uphill foundation slopes) on the uplift pressure, seepage discharge and exit gradient under hydraulic structures. In order to reach this goal, a numerical model has been developed in which the general equation of fluid flow in non-uniform; anisotropic soil is solved by the finite volume method on a structured grid. The model validation was performed using the measured data from experimental tests. The results of the model validation indicated that the model calculates the seepage discharge and uplift pressure with a maximum error of less than 3.79% and 3.25%, respectively. The results also indicated that by increasing the downhill foundation slope (DFS) the uplift force decreases, but the exit gradient and seepage discharge increase. Moreover, by increasing the uphill foundation slope (UFS), the uplift force increases but the exit gradient and seepage discharge decrease. In addition, the results demonstrate that by increasing the length of the cut-off wall the effect of the DFS on decreasing and UFS on increasing the uplift pressure force becomes more severe. However, the effect of the DFS on increasing the seepage discharge and UFS on decreasing the seepage discharge becomes milder as the length of the cut-off wall increases. By increasing the DFS, from zero to -15%, the exit gradient increases 19.75% and 14.4% for 1 m and 6 m cut-off lengths, respectively.
Although the impervious layer under a hydraulic structure is rarely flat, the effect of the impervious layer's slope, under the hydraulic structure, on seepage characteristics has not been studied to ...date. Therefore, this study investigated the effect of the downhill and uphill impervious layer's slope (downhill/uphill foundation slopes) on the uplift pressure, seepage discharge and exit gradient under hydraulic structures. In order to reach this goal, a numerical model has been developed in which the general equation of fluid flow in non-uniform; anisotropic soil is solved by the finite volume method on a structured grid. The model validation was performed using the measured data from experimental tests. The results of the model validation indicated that the model calculates the seepage discharge and uplift pressure with a maximum error of less than 3.79% and 3.25%, respectively. The results also indicated that by increasing the downhill foundation slope (DFS) the uplift force decreases, but the exit gradient and seepage discharge increase. Moreover, by increasing the uphill foundation slope (UFS), the uplift force increases but the exit gradient and seepage discharge decrease. In addition, the results demonstrate that by increasing the length of the cut-off wall the effect of the DFS on decreasing and UFS on increasing the uplift pressure force becomes more severe. However, the effect of the DFS on increasing the seepage discharge and UFS on decreasing the seepage discharge becomes milder as the length of the cut-off wall increases. By increasing the DFS, from zero to -15%, the exit gradient increases 19.75% and 14.4% for 1 m and 6 m cut-off lengths, respectively.
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