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Stability analysis of the Vallcebre translational slide,Eastern Pyrenees (Spain) by means of a GIS 总被引：4，自引：0，他引：4
The stability of the landslide of Vallcebre has been evaluated by means of a GIS. The landslide mechanism is a translational failure which has been analysed as an infinite slope. Soil strength parameters and groundwater conditions are obtained from laboratory tests and monitoring devices. Geometric parameters necessary to compute the factor of safety at each individual cell are generated by interpolation from the boreholes present in the landslide. The results have been checked with the actual behaviour of the landslide and are consistent. The comparison between a conventional slope stability analysis and the GIS-based approach gives similar results, showing the feasibility of the latter. 相似文献
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Prediction of ground displacements and velocities from groundwater level changes at the Vallcebre landslide (Eastern Pyrenees, Spain) 总被引：2，自引：5，他引：2
In active landslides, the prediction of acceleration of movement is a crucial issue for the design and performance of warning systems. The landslide of Vallcebre in the Eastern Pyreenes, Spain, has been monitored since 1996 and data on rainfall, groundwater levels and ground displacements are measured on a regular basis. Displacements observed in borehole wire extensometers have shown an immediate response of the landslide to rainfall episodes. This rapid response is likely due to the presence of preferential drainage ways. The occurrence of nearly constant rates of displacement in coincidence with steady groundwater levels suggests the presence of viscous forces developed during the movement. An attempt to predict both landslide displacements and velocities was performed at Vallcebre by solving the momentum equation in which a viscous term (Bingham and power law) was added. Results show that, using similar rheological parameters for the entire landslide, computed displacements reproduce quite accurately the displacements observed at three selected wire extensometers. These results indicate that prediction of displacements from groundwater level changes is feasible. 相似文献
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Geomorphic effects observed in the Barranco (creek) de Arás basin are used to characterize the flood. Sediment features allow to qualify the flood as essentially a water flow. Using the critical section method, the peak flood discharge is estimated to be between 400 and 600 m3 s−1. Similar results were obtained using a paleohydraulic formula based on the size of the largest mobilized clasts. Using the rational method with available rainfall data, the discharge for a recurrence interval of 500 years is estimated to be between 150 and 200 m3 s−1. These results agree with predictions obtained using curves of peak discharge versus basin area based on regional data. Several trenches dug on the fan showed that the size of boulders mobilized by the event is larger that those left by previous floods at the same place. When the estimated peak flood discharge is related to the basin area, values between 20 and 30 m3 s−1 km−2 are obtained, demonstrating that the Barranco de Arás flood was most unusual. 相似文献
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G. Matas N. Lantada J. Corominas J. A. Gili R. Ruiz-Carulla A. Prades 《Landslides》2017,14(5):1565-1578
A rockfall is a mass instability event frequently observed in road cuts, open pit mines and quarries, steep slopes and cliffs. After its detachment, the rock mass may disaggregate and break due to the impact with the ground surface, thus producing new rock fragments. The consideration of the fragmentation of the rockfall mass is critical for the calculation of the trajectories of the blocks and the impact energies and for the assessment of the potential damage and the design of protective structures. In this paper, we present RockGIS, a GIS-based tool that simulates stochastically the fragmentation of the rockfall, based on a lumped mass approach. In RockGIS, the fragmentation is triggered by the disaggregation of the detached rock mass through the pre-existing discontinuities just before the impact with the ground. An energy threshold is defined in order to determine whether the impacting blocks break or not. The distribution of the initial mass between a set of newly generated rock fragments is carried out stochastically following a power law. The trajectories of the new rock fragments are distributed within a cone. The fragmentation model has been calibrated and tested with a 10,000 m3 rockfall that took place in 2011 near Vilanova de Banat, Eastern Pyrenees, Spain. 相似文献
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Rockfall risk assessment to persons travelling in vehicles along a road: the case study of the Amalfi coastal road (southern Italy) 总被引：2，自引：0，他引：2
The paper deals with the assessment of rockfall risk to persons travelling in vehicles along the SS163 road, an important transportation corridor supporting a high vehicle traffic within the well-known tourist area of the Amalfi Coast (southern Italy). To this aim, the Rockfall Hazard Rating System (RHRS) and quantitative risk assessment (QRA) procedures, in this latter case for three rockfall risk scenarios, are applied. With reference to a large portion (33.820 out of a total of 50.365 km) of the SS163 road, the obtained QRA results highlight that, although the estimated individual risk to life satisfies the adopted tolerable risk criterion, the computed societal risk cannot be tolerated. Starting from this result, site-specific QRA analyses—carried out with reference to some road sections chosen on the basis of the RHRS results—allow the detection of the SS163 portions where the individual risk to life exceeds the tolerable risk threshold and, then, the recourse to mitigation measures could reveal necessary. In this regard, RHRS and QRA methods can be considered complementary tools in prioritizing the road sections where construction funds can be profitably spent in order to mitigate the rockfall risk with reference to both direct consequences (life loss) and indirect ones (traffic delay and diversions). 相似文献
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A large landslide (40 × 106 m3) 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. 相似文献
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The paper presents a time-dependent 2D numerical model which has been developed with the purpose of highlighting the effects of the slope foot evolution on the behaviour of slow-moving landslides. The model allows to quantitatively analyse how foot mass variations can influence the stability and the movement rates of the landslide.The landslide body is modelled as composed of two rigid blocks sliding on two different planes and interacting through a common boundary, which position is assumed fixed during the analysis. A finite difference approach is used to discretize the time. For each time increment, changes in model parameters are allowed, including variations in shearing resistances, groundwater level and block masses (in order to simulate foot erosion). During each iteration, the overall stability of the system is checked computing the safety factor, assuming that the percentage of mobilized shear strength is the same for the three surfaces. If the system is not stable or if it is not at rest, the velocity of the system is computed solving the momentum equations for the two blocks taking into account destabilising and resisting forces, the mechanical interaction between the blocks and viscous components. Computed velocities are iteratively used to compute mass accumulation at the foot, which in turn results in a change of the stability condition of the system.Examples are provided in order to highlight the roles of the model parameters. Finally, the application to a real landslide (Vallcebre, Spain) is presented which shows the advantage of considering the foot mass in the analysis of the displacement trends and the possibility to take into account the foot erosion in the long-term behaviour of the slope. 相似文献
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