Structurally controlled rock slope deformation in northern Norway

Abstract

Gravitational forcing of oversteepened rock mass leads to progressive failure, including rupture, creeping, sliding and eventual avalanching of the unstable mass. As the point of rupture initiation typically follows pre-existing structural discontinuities within the rock mass, understanding the structural setting of slopes is necessary for an accurate characterisation of the hazards and estimation of the risk to life and infrastructure. Northern Norway is an alpine region with a high frequency of large rock slope deformations. Inherited structures in the metamorphic bedrock create a recurring pattern of anisotropy, that, given certain valley orientations, causes mass instability. We review the geomorphology, structural mechanics and kinematics of nine deforming rock slopes in Troms County, with the aim of linking styles of deformation. The limits of the unstable rock mass follow either foliation planes, joint planes or inherited faults, depending on the valley aspect, slope angle, foliation dip and proximity to fault structures. We present an updated geotechnical model of the different failure mechanisms, based on the interpretations at each site of the review.

Integrated Field Surveying and Land Surface Quantitative Analysis to Assess Landslide Proneness in the Conero Promontory Rocky Coast (Italy)

“…Large disruptive landslides may represent the ultimate stage of the MRC process that can culminate in paroxysmal events (like rock avalanches); nevertheless, these ultimate events are anticipated by gravity-driven deformations which represent the strain effect of the rock mass viscous rheology. When these deformations develop into abrupt and generalized slope failures, it is caused by an increasing strain rate over time [10]. In particular, threshold conditions can be reached when the stationary creep stage evolves into an accelerating creep stage [11,12].…”

Cylindrical Caved Space Stability Analysis for Extension Prediction of Mining-Induced Surface Subsidence

“…The long-term strength is involved to test the stability of surrounding isotropic rock in a long duration of time because of the consideration of time effect, such as rock creep or the saturation by surface or underground water. However, rare analytical solutions regarding long-term strength of discontinuities have been reported, even though the impact of time on discontinuities' strength has been commonly observed [40,41]. Thus, the time effect is not involved in the proposed model for the slip failure (Equations ( 11), (12), and (13a)-(13d)), and this leads to observed orientation range where surface subsidence extension that takes place is larger than the predicted.…”

Large-Scale and Deep-Seated Gravitational Slope Deformations on Mars: A Review

“…The control factors of DSGSDs are numerous and mainly related to the characteristics of the relief and to the inherited and pre-existing structures [17,25]. Among them, of particular importance are tectonic structures such as folds and faults [17,19,26,30,35,39,42,47,48,76,[78][79][80] and bedding planes or schistosity [21,35,48,51,81]. These structures act as preferential weakness planes (or zones) and affect the geomechanical and rheological properties of rock masses [18,21,[49][50][51].…”

“…Some authors identified the absence of continuous sliding surface or basal shear zone as a typical feature of DSGSDs, thus considering them as discriminating elements with respect to "conventional" landslides [14]. Notwithstanding, these features have been recognized or inferred in many DSGSDs [15,17,18,[31][32][33][34][35] and so they have lost their value as discriminating element.…”

“…Generally speaking, large-scale gravitational deformations are controlled by preexisting and inherited geological structures, such as folds, faults, bedding planes, and schistosity [17,19,21,30,35,39,42,47,48], which act as a kinematic release and directly affect the geomechanical and rheological characteristics of rock mass at the slope scale [18,21,[49][50][51]. Not infrequently, these deformations can have a paroxysmal evolution and evolve into large landslides and slope collapses [20,[52][53][54].…”