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The Hope Slide, which occurred on January 9, 1965, involved an estimated 47-Mm3 of meta-volcanics and intrusive rocks. Previous workers reported the presence of tectonic structures (faults and shear zones) along the failure surface at the Hope Slide. These tectonic features were investigated in detail to assess their effects on rock-mass quality and the related implications for slope stability. This paper integrates basic field and laboratory concepts from structural and engineering geology. Subdividing the failure area into structural domains allowed distinct discontinuity sets to be associated with specific tectonic structures. The Geological Strength Index (GSI) was used to estimate the rock-mass damage related to the tectonic structures. Low GSI values were seen to outline tectonic damage zones. Point-load tests were used to characterise the compressive strength of rocks adjacent to the tectonic structures. Strength anisotropy, tentatively attributed to damage caused by a large shear zone, was observed in greenstone samples. Seepage zones along the failure surface were observed preferentially along shallow discontinuities that dipped downslope and in rock masses of good quality (GSI > 40). An alternative morphology of the slope failure is proposed by distinguishing between the extent of the surficial damage due to the rock-slope failure and the zone of failed material (depletion zone). For the first time, a kinematic mechanism for the Hope Slide is proposed, based on a preliminary 3-dimensional block model. A pre-1965 DEM was produced from estimates of material lost and gained as reported by previous workers. The pre-1965 DEM revealed that the tectonic structures recognised during fieldwork bounded the material that failed in the 1965 event. 相似文献
2.
Stability analysis of the 2007 Chehalis lake landslide based on long-range terrestrial photogrammetry and airborne LiDAR data 总被引：1，自引：1，他引：0
Marc-André Brideau Matthieu Sturzenegger Doug Stead Michel Jaboyedoff Martin Lawrence Nicholas J. Roberts Brent C. Ward Thomas H. Millard John J. Clague 《Landslides》2012,9(1):75-91
On December 4th 2007, a 3-Mm3 landslide occurred along the northwestern shore of Chehalis Lake. The initiation zone is located at the intersection of the
main valley slope and the northern sidewall of a prominent gully. The slope failure caused a displacement wave that ran up
to 38 m on the opposite shore of the lake. The landslide is temporally associated with a rain-on-snow meteorological event
which is thought to have triggered it. This paper describes the Chehalis Lake landslide and presents a comparison of discontinuity
orientation datasets obtained using three techniques: field measurements, terrestrial photogrammetric 3D models and an airborne
LiDAR digital elevation model to describe the orientation and characteristics of the five discontinuity sets present. The
discontinuity orientation data are used to perform kinematic, surface wedge limit equilibrium and three-dimensional distinct
element analyses. The kinematic and surface wedge analyses suggest that the location of the slope failure (intersection of
the valley slope and a gully wall) has facilitated the development of the unstable rock mass which initiated as a planar sliding
failure. Results from the three-dimensional distinct element analyses suggest that the presence, orientation and high persistence
of a discontinuity set dipping obliquely to the slope were critical to the development of the landslide and led to a failure
mechanism dominated by planar sliding. The three-dimensional distinct element modelling also suggests that the presence of
a steeply dipping discontinuity set striking perpendicular to the slope and associated with a fault exerted a significant
control on the volume and extent of the failed rock mass but not on the overall stability of the slope. 相似文献
3.
Structural and engineering geology of the East Gate Landslide, Purcell Mountains, British Columbia, Canada 总被引：3，自引：0，他引：3
The East Gate Landslide is a prehistoric landslide that was reactivated in January 1997. The slope failure took place in the lower greenschist metasedimentary units of the Precambrian Horsethief Creek Group. The Grizzly Creek Thrust is a regional overturned fault that coincides with the location of the headscarp of the East Gate Landslide. Four discontinuity sets were recognised from detailed engineering geological mapping of the headscarp and surrounding area. The main scarp of the section reactivated in 1997 was sub-divided into three structural domains based on its position within the landslide, lithology, and orientation of the discontinuity sets. Limit-equilibrium techniques, finite-difference (FLAC) and distinct-element (UDEC) codes were used to investigate the failure mechanism of the 1997 event. The results of the field observations and numerical models suggest that the 1997 failure involved a complex mechanism incorporating components of rock-slumping, bi-planar, and pseudo-circular failure that was controlled by both the orientation of the discontinuity sets and reduced rock-mass quality due to tectonic deformation. 相似文献
4.
Evaluating Kinematic Controls on Planar Translational Slope Failure Mechanisms Using Three-Dimensional Distinct Element Modelling 总被引：1，自引：0，他引：1
This paper investigates the importance of kinematic release mechanisms on planar translational slope failure using three-dimensional distinct element codes. The importance of the dip and dip direction of the rear, basal and lateral release surfaces and their influence on failure mechanism, dilation, and the development of step-path failures is illustrated. The three-dimensional block shape and volume of the unstable rock masses simulated with the different discontinuity set geometries are characterized. Two assumed three-dimensional slope models are investigated in order to assess the importance of varying kinematic confinement/release mechanisms. These two assumed boundary conditions are shown to be critical in the development of asymmetrical rock mass deformation patterns. Scale effects due to the block size and discontinuity persistence are shown to control the calculated displacement and failure mechanisms. The numerical modelling results are also demonstrated to be sensitive to the assumed normal and shear stiffness of the discontinuities. The influence of the factors investigated on the failure of a single rock block versus a rock mass are compared and discussed. 相似文献
5.
Three-dimensional slope stability analysis of South Peak, Crowsnest Pass, Alberta, Canada 总被引：2，自引：2，他引：0
Marc-Andr�� Brideau Andrea Pedrazzini Doug Stead Corey Froese Michel Jaboyedoff David van Zeyl 《Landslides》2011,8(2):139-158
South Peak is a 7-Mm3 potentially unstable rock mass located adjacent to the 1903 Frank Slide on Turtle Mountain, Alberta. This paper presents
three-dimensional numerical rock slope stability models and compares them with a previous conceptual slope instability model
based on discontinuity surfaces identified using an airborne LiDAR digital elevation model (DEM). Rock mass conditions at
South Peak are described using the Geological Strength Index and point load tests, whilst the mean discontinuity set orientations
and characteristics are based on approximately 500 field measurements. A kinematic analysis was first conducted to evaluate
probable simple discontinuity-controlled failure modes. The potential for wedge failure was further assessed by considering
the orientation of wedge intersections over the airborne LiDAR DEM and through a limit equilibrium combination analysis. Block
theory was used to evaluate the finiteness and removability of blocks in the rock mass. Finally, the complex interaction between
discontinuity sets and the topography within South Peak was investigated through three-dimensional distinct element models
using the code 3DEC. The influence of individual discontinuity sets, scale effects, friction angle and the persistence along
the discontinuity surfaces on the slope stability conditions were all investigated using this code. 相似文献
6.
Analysis methods for block toppling are most commonly undertaken in two dimensions. This paper investigates the influence
of discontinuity orientations on three-dimensional block toppling mechanisms using a three-dimensional distinct element code.
The three-dimensional models allow one to kinematically appraise if toppling conditions derived for two-dimensional geometries
can be extended into three dimensions. Two conceptual model geometries were considered in order to represent a road cut or
open-pit bench. The first geometry examined a slope with fixed vertical lateral boundaries, while the second geometry assumed
an unrestrained lateral slope as a model boundary condition. This “along-strike slope profile” of the models was found to
play an important role in the failure mechanism and displacement direction. The dip direction and dip angle of the toppling,
basal and lateral release discontinuities were varied one at the time using angular ranges of up to 30° from an assumed mutual
orthogonal relationship. This made it possible for the influence and importance of each discontinuity set to be independently
evaluated. The results are presented in a stereographic format with preliminary zones outlining discontinuity aspect combinations
that potentially result in block toppling failures. 相似文献
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