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Planar sliding is a typical failure mode of landslides, in which an unstable rock block slides along a weak plane, resulting in a rapid movement. This study proposes a particulate interface model (PIM) that considers velocity-dependent friction behavior to simulate the planar sliding behavior of the particulate DEM. To validate the performance of the proposed model, the results of a DEM simulation of the planar sliding of a rigid block are compared with the analytical dynamic solution. The results reveal that the PIM simulation is consistent with the analytical dynamic solution with or without consideration of the velocity-dependent friction law. The ordinary contact model does not accurately reflect the theoretical dynamics owing to the high resistance. The smooth-joint model underestimated the shear resisting force of the interface and yielded excessively high velocity and displacement of the block. With respect to the deposition distribution, the different interface models yielded the various velocities before impact, and therefore various failure patterns of the block and appearances of the deposition. The block velocity significantly influences the number of cracks. The results of the analysis reveal that the PIM can capture the planar sliding and deposition behavior of particulate DEM. [ABSTRACT FROM AUTHOR]

A number of large landslides, which have strongly affected fluvial processes in the upstream catchment of the Minjiang River along the eastern margin of the Tibetan Plateau, Sichuan, were investigated with regard to both geological structure and topographic development. Topographic analysis suggested that there is a major knickpoint that formed not as a result of landslides but via tectonic activity and that the knickpoint propagated upstream, forming an inner gorge and undercutting and destabilizing nearby slopes. The effects of the knickpoint propagation and inner gorge formation on slope stability are dependent on the geometrical relationships between the river and geological structures. When the geological trend is normal or highly oblique to the river axis, landslides generally do not occur, but gigantic rockslides have occurred on one side of the Minjiang valley, which can be attributed to a wedge structure consisting of bedding planes and joints with intersections dipping valleyward and tight folds with hinges plunging valleyward. When the beds are planar, moderately dipping, and strike nearly parallel to the river, buckling deformation commonly occurs on cataclinal slopes, often transforming into catastrophic failure. Landslide dams form another type of knickpoint on the river channel that gradually disappear from the downstream to upstream as a result of river erosion. Our findings strongly suggest that the study of slope development by river incision must consider geological structures and that an understanding of geological structures and river incision history can provide a conceptual model for the prediction and mitigation of geohazards in tectonically active drainage basins. [ABSTRACT FROM AUTHOR]

Excavation in highly stressed grounds may lead to violent compressive failures of rock or violent slip along discontinuities in the vicinity of the underground space. Violent failures, usually with anomalous seismic signatures, are characterized with radiating excess energy during the failure, endangering the safety and productivity of the operation. This paper adopts a numerical methodology, developed in the Universal Distinct Element Code (UDEC) for quantitatively studying the occurrence and intensity of violent failures, and advances it for respective analyses in tunneling and shaft-boring operations. The methodology enables estimating the radiated energy as a measure for evaluating the occurrence and relative intensity of violent failures. We first validate the radiated energy calculation in the models against analytical solutions for the formation of a circular opening, analogous to the geometry of tunnels and shafts. After reviewing the concept of violent failures by ideal models, we explore the effects of different factors on the occurrence and intensity of violent failures caused by an excavation into brittle rock or next to a preexisting fault. Limited cases studied in this paper demonstrate that different combinations of the rock elastic modulus and post-failure response of rock and discontinuity can result in a violent failure with various intensities. Larger excavations under higher deviatoric stresses can intensify the potential violent failure mostly through expanding the rock failure zone or the slip area on the activated fault. However, as opposed to the radiated energy, using the failure zone volume and fault slip area alone may lead to underestimating or overestimating the intensity of possible violent failures in a modeling practice. The energy-based analyses outlined in this paper provide a rational yet simple means for quantitatively studying violent failures in potentially complex geological conditions and excavation layouts. [ABSTRACT FROM AUTHOR]

• The NaCl solution is more corrosive than the Na 2 SO 4 solution for grouted rock bolts. • The greater the working stress is, the more the bonding strength will decrease. • The "initial tension rising stage" of corroded rock bolts almost disappears. • A regression model is established under the coupled effect of stress and corrosion. The corrosion of rock bolts buried in rock and soil layer is obviously different from that of general ground structure. The main corrosion sources of the latter come from the air and the corrosion sources of rock bolts are not only from the air, but also the rock-soil body and groundwater. At the same time, the corrosion of rock bolts is under the stress state in practical engineering. To study the stress-corrosion effect of grouted rock bolts, using a self-developed rock bolt stress corrosion device, corrosion tests were conducted under different working stresses (10 kN, 35 kN and 60 kN), corrosion environments (5% Na 2 SO 4 , 1.5% NaCl + 2.5% Na 2 SO 4 and 3% NaCl) and corrosion times (3 d, 7 d and 14 d). The results show that the NaCl solution is more corrosive than the Na 2 SO 4 solution for the grouted rock bolts with more rust productions. The maximum tension of rock bolts under the condition of no corrosion reaches 60.16 kN, and under the T-60-A-14d working condition, the maximum tension of rock bolts is only 31.32 kN. Compared with the condition of no corrosion, the maximum tension of grouted bolts is lowered by 25%–50% under the different working stresses and corrosion conditions. The maximum difference values of the relative bonding strength of rock bolts is 14.9% under corrosion time, 13.1% under working stress and 9.4% under corrosion environment. It shows that the corrosion effect of the rock bolt under the corrosion time is the most significant, and the working stress is second. The influence of the corrosion environment on the bonding strength of the grouted rock bolts is the least important. The slip curves of the rock bolts under the environment of no corrosion have an obvious rising stage, and uplift of tension accounts for about 62.9% of the maximum tension. The final residual tension is stable at approximately 25 kN. The bonding slip curves of corroded rock bolts, of which the "initial tension rising stage" almost disappears, demonstrate a trend of steady decline. The minimum final residual tension is less than 10 kN (T-35-B-14d). The larger the working stress is, the more significant the degradation effect of anchor tension is. It is shown that the current test and study on the corrosion of anchor bolts can not accurately reflect the corrosion law of rock bolts in practical engineering if only the material or the axial force with small value is applied. The influence of stress on the corrosion test of rock bolts can not be ignored. [ABSTRACT FROM AUTHOR]

• Propose a simplified model for CLT wall lateral behavior under varying boundaries. • Demonstrate proposed model's accuracy and limitations via experiments. • Illustrate how wall configurations and boundary conditions impact on CLT behavior. A new simplified mechanistic model was developed in this study to predict the rocking and sliding lateral response of a CLT panel wall under monotonic pushover with different boundary and gravity loading conditions based on an approximation of the principle of virtual work. Namely, for a given forced lateral displacement increment, the CLT wall will engage in a combination of rocking and sliding motion that will minimize the total work needed to go through that displacement increment. The proposed model was compared to the existing test results to illustrate its ability to capture the two types of wall behavior. Being a simplified mechanistic model, a number of material nonlinear characteristics such as the local crush of wood and the biaxial interaction of the connectors were not captured, resulting in a backbone characterization accuracy not as good as some existing well-calibrated models. However, the contribution of the study is to provide a mechanistic approach to address the switching between rocking and sliding behavior of CLT panelized walls under different boundary conditions. Using the model, a sensitivity analysis was conducted to investigate the effect of wall configurations and boundary conditions on the behavior of CLT shear walls. [ABSTRACT FROM AUTHOR]

In this paper I report on the poorly known terrestrial mollusk fauna of Great Basin National Park (Snake Range) of the central Great Basin, USA. Mollusk species and numbers were recorded according to habitat affinities defined by a combination of rock type, geomorphology, plant communities, and water sources. A total of 6892 individuals representing 18 species of land snails and 1 species of slug were identified from 50 stations within GBNP during the period of spring 2014 through summer 2016. Mollusks were surveyed by 186 soil/litter samples and 1755 min of hand searching. Twelve habitat types included 2 xeric limestone/dolomite environments with conifer/aspen woodlands and no perennial waters (10 species in woodland litter and 15 species in rock slides below cliff faces). Two habitats dominated by granite/quartz rock with conifer/aspen woodlands and perennial streams supported 12 species in woodland litter and 13 species in rock slides. Eight species were recorded from a lower-elevation riparian habitat with cottonwood and shrubs. Two high-elevation habitats (approximately 3000 m) without perennial waters and dominated by bristlecone pine supported 1 species in limestone and 3 species in granite/quartz. A single high-elevation habitat (2800 m) of xeric pinyon pine/mountain mahogany and granitic/quartz rock supported 4 species. Two lower-elevation habitats (1800 m) supported 2 species in a sagebrush steppe, while no mollusks were found in pinyon pine/Utah juniper woodland. Two localized mesic habitats were associated with boggy streamsides and natural springs and supported 11 species each. The single species of slug Deroceras laeve and a species of succineid snail are restricted to these 2 habitat types. The 4 most common species of land snails (Pupilla hebes, Vallonia cyclophorella, Euconulus fulvus, and Vitrina pellucida) were present in 7 to 9 of the habitat types and represented 70% of the individual shells recovered. Taxonomic and biogeographical notes are included to allow for a better understanding of the species present in GBNP and the relationship of these species to the larger distribution of the terrestrial mollusks within Nevada and the Great Basin. [ABSTRACT FROM AUTHOR]

Landslide dam resulted from the natural blockages of river channels caused by rockslide-derived debris is easy to burst, which usually leads to a catastrophic damage. In this work, the physical model tests were carried out to investigate the movement process and accumulation characteristics of rock fragments on sliding surfaces with different characteristics, mainly taking into consideration of the influence of the initiated angle, sliding region angle and sliding bed roughness. The results show that after particle separation and collision during the movement process of rock fragments, large particles were widely distributed on the surface of the final deposit while small particles were deposited at the bottom. The sliding region angle and the roughness of the sliding surface had a great influence on the front inclination angle of the deposit dam. The sliding region angle also had a significant influence on the accumulation area and dam morphology in the rough group, while only a little effect was observed on the dam morphology in the smooth group. The distribution of the particles in the deposit dam was affected mainly by the roughness of the sliding surface. • The movement process and accumulation characteristics of rock fragments on sliding surfaces with different characteristics were investigated. • Large particles were widely distributed on the surface of the final deposit. • The sliding region angle and the roughness had a great influence on the front inclination angle. [ABSTRACT FROM AUTHOR]

The stability of a granitic rock cut located within a densely populated residential area in Madinah, Saudi Arabia, was investigated to avoid rock failure consequences. Based on the field inspection, this cut is characterized by a very irregular face leading to the occurrence of rock sliding and rockfall events in the area. Moreover, this cut lacks any type of stabilization or protection measurements. Kinematic analysis was used to analyze rock sliding events while RocFall software was used to analyze the mechanism of rockfall incidents. The results indicated to the high probability of wedge failures to take place (≈ 67%) as well as the toppling failures but with lower probability (< 10%). Furthermore, it was found that some large loose rock blocks on the cut surface could be easily triggered and fallen down reaching all onto the road and causing loss of life and damages to properties. As a result, this research recommended immediate scaling for loose rocks as well as constructing effective catch ditch in addition to anchoring large intact rocks. [ABSTRACT FROM AUTHOR]

Failures at geological discontinuities often play a dominant role in the prediction of rockslides. In this study, a second order work criterion was used to analyze this type of problem by its constitutive instabilities, as it can expound all physical instabilities by divergence, except flutter instabilities. Derived from vanishing of the second order work, a matrix analysis focusing on the instability of geological discontinuities in two dimensions was performed. A real rockslide was simulated in a 2-D framework, and the second order work criterion was used to predict the occurrence of the rockslide. The numerical results were compared to monitoring data. Rockslides could be considered as processes involving a transition from a static loading to a dynamic response including a sudden burst of kinetic energy. Furthermore, a relationship existed between the second order work and second order kinetic energy. Hence, kinetic energy estimation was performed using two numerical approaches derived from this relationship and compared. [ABSTRACT FROM AUTHOR]

Landslides are among hazards that undermine the social, economic, and environmental well‐being of the vulnerable community. Assessment of landslides vulnerability reveals the damages that could be recorded, estimates the severity of the impact, and increases the preparedness, response, recovery, and mitigation as well. This study aims to estimate landslides vulnerability for the western province of Rwanda. Field survey and secondary data sources identified 96 landslides used to prepare a landslides inventory map. Ten factors—altitude, slope angles, normalized difference vegetation index (NVDI), land use, distance to roads, soil texture, rainfall, lithology, population density, and possession rate of communication tools—were analyzed. The Analytical Hierarchy Process (AHP) model was used to weight and rank the vulnerability conditioning factors. Then the Weighted Linear Combination (WLC) in geographic information system (GIS) spatially estimated landslides vulnerability over the study area. The results indicated the altitude (19.7%), slope angles (16.1%), soil texture (14.3%), lithology (13.5%), and rainfall (12.2%) as the major vulnerability conditioning parameters. The produced landslides vulnerability map is divided into 5 classes: very low, low, moderate, high and very high. The proposed method is validated by using the relative landslides density index (R‐index) method, which revealed that 35.4%, 25%, and 23.9% of past landslides are observed within moderate, high, and very high vulnerability zones, respectively. The consistency of validation indicates good performance of the methodology used and the vulnerability map prepared. The results can be used by policy makers to recognize hazard vulnerability lessening and future planning needs. Integr Environ Assess Manag 2019;00:000–000. © 2019 SETAC Key Points: Disaster vulnerability increases mainly due to lack of timely risk information sharing and integrated vulnerability assessment, which would enhance the risk awareness and preparedness.The Analytic Hierarchy Process weighted the vulnerability causal factors, then the geographic information system helped to spatially distribute the vulnerability within the study area.The findings contribute to future strategic planning and mitigation strategies toward disaster risk reduction and sustainable development. [ABSTRACT FROM AUTHOR]

When a destructive landslide happens, geologists may be recruited to be part of the team carrying out the emergency response. An emergency response situation requires geologists to quickly acquire needed geologic information during an intense and stressful assignment. There are five significant operational approaches that are essential to ensure success in this situation. First, the geologists should fully understand and remain focused on the objectives of the response mission. Second, the landslide area must be accessed safely when collecting needed data. From a team standpoint, an injury negatively affects available data and time. Third, the landslide information that is developed must be reliable within the context of the mission and be obtainable within a limited time. Fourth, given the constraints on data collection imposed by an emergency response situation, the degree of uncertainty associated with the findings will need to be explained to ensure subsequent decision-making is done on a sound basis. Fifth, the information needs to be communicated to different audiences, who will range from individual team members to groups of people affected by the landslide. Whether providing documentation or making a presentation, the geologist will need to engage them by explaining the landslide information so it speaks to their needs. Experience gained serving on teams for a huge landslide damming a river in Dominica, West Indies, in 1997 and a large rock slide that buried a major highway in California in 2006 illustrate these important aspects for ensuring success when investigating landslides during an emergency response. [ABSTRACT FROM AUTHOR]

Highlights • New numerical procedures for bolt-rock interaction are proposed. • The calculation process is greatly simplified in the procedure with the slip case. • Two scenarios are comprehensively considered in the procedure with the non-slip case. • Differences of results for the slip and non-slip cases are compared. Abstract This paper aims to propose new numerical procedures for elasto-plastic analysis of the interactions between fully-grouted bolt and rock with slip and non-slip cases at a potential-failure interface. In the proposed procedure with the slip case, the iteration process accounts for the elongation of the bolt, and the calculation process is greatly simplified by considering only the initial and final states (i.e., no intermediate finite states as is the case for existing procedures) without compromising the accuracy of the predictions. In the proposed procedure with the non-slip case, the elasto-plastic solution of the plastic rock strain is rigorously derived; the two scenarios in which the length of the rock bolt is contained within the plastic zone or within the elastic zone are comprehensively considered. The obtained solutions of tensile force in the bolt, shear stress at the potential-failure interface, rock displacement and stress components in the rock from the proposed procedures are validated by analyses with purely analytical methods and a commercial finite-difference program. With influences of rock quality and plastic softening behaviour of rock mass, the differences of the solutions in the slip and non-slip cases at potential-failure surface are compared; the dependency of the relative movement on the shearing stiffness at the potential failure interface is also investigated. [ABSTRACT FROM AUTHOR]

Although there have been rapid developments in the field of geomechanics and geotechnics in recent decades, understanding the instability mechanisms of geomaterials and the prediction of landslides remain worldwide problems. The objective of this study was to present a real rockslide prediction by a novel monitoring system and discuss a numerical approach as an assistant tool. On one hand, a real rockslide that occurred in an open-pit mine was monitored using a novel constant-resistance-large-deformation (CRLD) cable, and the successful prediction of a rockslide and evacuation of personnel and equipment were presented. On the other hand, the stability of the studied rock slope was controlled by a major fault. A material instability criterion was selected to analyze the failure of the major fault and the rockslide mechanism. Finally, the material instability criterion was implanted into the FLAC3D software, and the real rockslide was simulated and analyzed in the framework of the finite difference method. The failure of the major discontinuity was discussed, the numerical results were compared with the real case, and reasonable explanations were proposed. [ABSTRACT FROM AUTHOR]

Ridge-top rockslides frequently cause huge property losses and casualties due to the difficulties involved in detecting their precursors by means of manual surveys. Their early identification and the surrounding area's evaluation in terms of potential danger are essential for preventing disasters. The recent large rockslide which occurred at Su Village, which is in possession of data related to pre-failure images, real-time video, and post-failure boreholes, is helpful for providing new insights into the processes associated with these events. Due to a strong sustained rainfall, a large volume of granite blocks rapidly descended from the upper part of the hillside, causing 27 deaths and destroying more than 20 houses. It is found that the early identification of the hazard associated with such rockfalls can be made by the analysis of remote sensing images and Persistent Scatterer Interferometry (PSI) analysis of Synthetic Aperture Radar (SAR) data. The depth-integrated continuum method, including taking the entrainment effect into account, was adopted to analyze the dynamic processes and to identify the areas at risk. The computational results show that the evaluated runout distance and extent match well with the field investigation results. The parameter sensitivity surrounding cohesion, coefficients of lateral earth pressure, and volume amplification were analyzed. It is demonstrated that the cohesion plays a significant role in the dynamic processes and the deposited area. However, the effects from the earth pressure coefficient and volume bulking are comparatively weaker. [ABSTRACT FROM AUTHOR]

The present paper presents a study of a particular instability mechanism observed in coastal ranges of southeastern Brazil. It consists of the failure of a saturated soil slope hit by a rock block detached from higher ground. In the rainy season lasting from November to March, slopes are near or at complete saturation. It is also common under these conditions, that blocks of rock masses of gneissic origins, mainly detaching from the rock mass and sliding along relief joints in higher elevations, acquire momentum to impact lower ground slopes consisting mainly by soil masses eventually saturated. The impact generates pore pressures, which can lead to failure of the slope. The present paper proposes to analyze this condition by using the generalized interpolation material point method (GIMP), a method suitable for analyzing the dynamic character of the problem as well as the generated failure mechanism and ensuing run-out of the failed mass. The paper presents details of the problem and of the coupled fluid-mechanical formulation of GIMP used in analysis. It also presents and discusses the obtained results of the analysis carried out. The paper also comments on the suitability of GIMP for analysis of this type of complex slope stability condition. [ABSTRACT FROM AUTHOR]

Terrestrial cosmogenic nuclide (TCN) exposure dating of boulders is frequently used for rockslide chronology. A well-recognized source of error that cannot be readily quantified is related to inheritance of TCN produced in the rock prior to failure. The effect of inheritance is not constant and will be greatest in the instance of a very recent shallow failure on a high-altitude surface with low event frequencies. We illustrate the effect by measuring 10Be concentrations in six boulders exposed for only 9 years before sampling, on a rock avalanche in Puerto Aysén, Chile. Their apparent exposure ages range from 216 ± 76 to 1755 ± 436 years. The mean apparent exposure age of a statistical cluster of three samples exceeds the real exposure time by 345 ± 36 years (3800%), implying that all sampled rock surfaces experienced pre-failure TCN production. A reconstructed pre-failure topography enables the analysis of possible pre-failure boulder positions and an estimate of the range of possible inherited concentrations along a 2D transect. Despite a maximum failure-mass thickness of 110 m, the boulders seem to have originated from depths shallower than 14 m. Because of the likelihood that large boulders, prioritized for TCN sampling, originate from relatively shallow pre-failure depths owing to surface-near transport with minor turbation, it is necessary to consider potentially inherited TCN concentrations and their effect on the age determination, especially in cases of young rockslides, where the commonly adjusted effects of boulder erosion and snow, ash, or vegetation shielding are negligible in comparison. [ABSTRACT FROM AUTHOR]

Instrumental monitoring of displacement rates of slow-moving rockslides is limited to an insufficient length of the pre-catastrophic failure deformation time. Prehistorical slip rates need to be considered to provide context for monitoring data in relation to the length of the failure process. Cosmogenic 10Be exposure ages (n = 10) on the backscarp of the Gamanjunni-3 rockslide (northern Norway) are between 5.3 ± 0.5 ka and 1.2 ± 0.1 ka. These ages were adjusted for prefailure nuclide production at depth based on the 10Be concentration in quartz from a stable horizontal bedrock surface above the rockslide. Displacement initiated between 6.6 and 4.3 ka with a relatively fast or instantaneous displacement rate that decelerated a few hundred years after initiation. Slide initiation coincided with the end of the Holocene thermal optimum in northern Norway. The age-height relationship on the backscarp yields an average paleo-slip rate of 28 (-5/+7) mm/yr. This is significantly slower than present-day rates of 54 mm/yr. However, during slide initiation, slip rates were faster than present-day rates. Considering its location within the modern permafrost zone and the observations from instrumental and Holocene displacement rates, we suggest that future global climate changes will influence the Gamanjunni-3 block slip rate. [ABSTRACT FROM AUTHOR]

Medial moraines deposited by former glaciers and ice sheets are rare in Scotland. The most prominent example is the Sgriob na Caillich moraine, which consists of two to four parallel belts of angular quartzite boulders that extend northwestwards for over 3.5 km from the SW flank of Beinn an Oir on the Isle of Jura. The boulder belts extend to within 300 m of the present coastline, where they are truncated by a low bluff and raised marine terrace. The source of the moraine coincides with bedrock gullies and cliffs that represent the scars of former rock-slope failure(s), indicating that the moraine debris was sourced by one or more rockfalls or rockslides onto the ice surface after Beinn an Oir had emerged from the thinning ice cover as a nunatak. Exposure dating of boulders on the moraine indicate that it formed at 16.6 ± 0.8 ka, consistent with the timing of ice-sheet retreat in this sector. The alignment of the moraine indicates ice-margin retreat to the SE; as regional ice-sheet retreat across the adjacent offshore shelf was to the NE, this anomaly implies that a residual icefield became stranded on Jura during ice-sheet retreat. [ABSTRACT FROM AUTHOR]

We studied a data set of 28 well‐preserved lunar craters in the transitional (simple‐to‐complex) regime with the aim of investigating the underlying cause(s) for morphological differences of these craters in mare versus highland terrains. These transitional craters range from 15 to 42 km in diameter, demonstrating that the transition from simple to complex craters is not abrupt and occurs over a broad diameter range. We examined and measured the following crater attributes: depth (d), diameter (D), floor diameter (Df), rim height (h), and wall width (w), as well as the number and onset of terraces and rock slides. The number of terraces increases with increasing crater size and, in general, mare craters possess more terraces than highland craters of the same diameter. There are also clear differences in the d/D ratio of mare versus highland craters, with transitional craters in mare targets being noticeably shallower than similarly sized highland craters. We propose that layering in mare targets is a major driver for these differences. Layering provides pre‐existing planes of weakness that facilitate crater collapse, thus explaining the overall shallower depths of mare craters and the onset of crater collapse (i.e., the transition from simple to complex crater morphology) at smaller diameters as compared to highland craters. This suggests that layering and its interplay with target strength and porosity may play a more significant role than previously considered. [ABSTRACT FROM AUTHOR]

Mudstones hosting Burgess Shale-type preservation of soft-bodied fossils are commonly held to be characterized by little to no bioturbation. This has been taken as evidence for bottom- water dysoxia or anoxia, along with anaerobic conditions in the sediment, which favored preservation of soft tissues by hindering decay. Although invisible on fresh and weathered surfaces, laminated claystone comprising the middle Cambrian (Drumian) Ravens Throat River Lagerstätte in the Rockslide Formation of the Mackenzie Mountains, northwestern Canada, is revealed by preparation of surfaces sawn parallel to bedding to exhibit extensive burrowing. Four types of burrows are distinguished: (1) rare large forms averaging 15 mm in diameter; (2) backfilled vertical burrows 3-6 mm wide; (3) oblique to horizontal burrows 2-4 mm wide and typically with meniscate backfilling; and (4) tiny, short, mostly vertical burrows 0.5-1 mm in diameter. The third group is the most common, locally completely bioturbating laminae and penetrating worm carcasses; it conforms to Planolites. A variety of ethologies is indicated, with the large type seemingly serving as a dwelling burrow and the smaller ones from deposit-feeding. Although dysoxic bottom conditions probably developed occasionally, the widespread burrowing argues for predominantly oxic conditions, and it indicates that restriction of bioturbation was probably not the most important factor leading to soft-tissue preservation. Bioturbation might be more common in other Cambrian Lagerstätten than is currently believed, and it is possible that low-oxygen conditions at the seafloor were not fundamentally necessary for Burgess Shale-type preservation. [ABSTRACT FROM AUTHOR]

The coal wall and floor of the longwall face in the steeply inclined coal seam are prone to damage, which seriously affects the advance of the working face.By establishing theoretical model, bottom friction experiments, numerical calculations, etc., the characteristics of coal seam roof breaking and caving rock sliding are studied, and the coal wall failure mechanism under different coal seam occurrence and mining conditions is revealed. The concrete measures to prevent coal wall damage and floor slip are put forward.The study shows that the caving rock from the roof of the longwall face in steeply inclined coal seams will form different degrees of filling in the goaf. From bottom to top, it forms three sections including "compact filling section", "uneven filling section"and "non-filling section".However, due to insufficient filling in the upper part of the working face, the dynamic pressure phenomenon is obvious, which is likely to cause serious coal wall slab and bottom plate slip phenomenon, and the working condition of the support will also become worse, which becomes the most unstable surrounding rock of the whole working face.The fragile area seriously affects the safe and efficient production of the working face, and is the key area for the surrounding rock control of the working face.The stability of the working floor is significantly affected by the stability of the coal wall.In actual production, it is found that when the coal seam occurrence and mining conditions are different, the coal wall failure generally presents three failure modes: "plastic-flow", "extrusion-slip"and "shear-slip".The use of a pseudo-tilt arrangement at the working face not only can significantly improve the stability of the coal wall and the bottom plate, but also effectively prevent the hydraulic support from falling and sliding, and can also avoid the occurrence of flying gangue at the working face.With the integration of conveyor and the "flexible reinforced coal wall", it is possible to realize the safe and efficient mining of longwall working face in steep coal seam, and effectively solve a series of rock formation control problems faced by the mechanized mining of steep coal seam. [ABSTRACT FROM AUTHOR]

Grounded in a case study of the Frank Slide, Canada's Deadliest Rockslide, this article introduces a new perspective on disaster sites as socio-cultural entities by way of correlating the specific technicality of scientific research and management of disaster sites with a broader conceptual framework from within the social sciences and spatial theories. Heritage sites such as the Frank Slide are often understood as protected places that benefit the image of a sovereign nation (i.e., a "place-myth"). It is often assumed that heritage sites need protection from natural elements and from human interference. But the case of the Frank Slide is different, insofar as (a) it is a heritage site made out of the remnants of a terrifying disaster and (b) it is predicted to be further damaged when its ensuing rockslide follows (sometime between now and 5,000 years). This makes the case of the Frank Slide an intriguing one for an interdisciplinary study, since it is made up of various overlapping temporalities belonging to the measurement-time of scientific monitoring, commodity-time of the tourism industry, myth-time of national identity, duration-time of cultural memory, and the anticipation-time of further disaster. The analysis considers how these disparate activities contribute to the vitalization, devitalization, and revitalization of place, in such a way that challenges the "dark tourism" paradigm that has come to frame disaster sites. This article thus proposes a unique synthesis between these times and practices contained within them in order to elucidate and explore how various overlapping temporalities make up the visible and invisible materials of a place. [ABSTRACT FROM AUTHOR]

Rock burst mitigation and monitoring is a challenge during deep coal mining. Theoretical analysis, numerical simulation, laboratory tests and field monitoring are all used for researching this issue. First, the occurrence mechanisms of three types of rock burst(i. e. , strain rock burst, fault slip rock burst and hard roof rock burst) are researched. Second, two new burst liability indexes are proposed to improve the evaluation system of burst liability, which makes theburst liability evaluation system more suitable for deep coal mining. Third, the precursor information characteristics of the three rock burst types are given. Forth, the corresponding monitoring-warning and combined pressure relief methods are proposed. At last, synchronization technique of drilling and monitoring is developed. Main conclusions are as follows:(1) Deep strain rock burst is the result that the energy accumulation of surrounding rock system is larger than that of superposition of energy release and energy dissipation. Compared with shallow mining, the released energy of deep hard roof fracturing increases and deep fault slips more easily. (2) When evaluating burst liability of deep strain rock burst and hard roof rock burst, burst energy speed indexes of unloading confining pressure and combined coal-rock need to be added except the national standard, respectively. For deep fault slip rock burst, the two new indexes are all need to be added. (3) Monitoring and warning of deep strain rock burst and deep hard rock burst should depend on energy and stress criteria, while for deep fault slip rock burst, energy criterion is the priority. (4) Priorities for mitigating deep strain rock burst are protective seam mining, large-diameter drilling, floor fracturing and water infusion. Priorities for hard roof rock burst are protective seam mining, roof fracturing, large-diameter drilling, floor fracturing and water infusion. Priorities for fault slip rock burst are protective seam mining, large-diameter drilling and water infusion. (5)When using the synchronization technique of drilling and monitoring, drilling powder and stress change can be monitored for potential burst warning during drilling process. System establishment of control technique based on scientific classification still will be the direction of future research. [ABSTRACT FROM AUTHOR]

The evolution of unstable rock slopes is a discontinuous process that is typically characterised by a succession of discrete events, each one giving rise to a new configuration of the rock face. If these events are put in a wider time frame, they can be seen as a local step contributing to the overall process. The advances in recognition systems, such as laser scanning or georadar techniques, allow to build numerical models of higher and higher precision, where the topographic and geostructural configurations may be precisely reconstructed. These improved capabilities open the possibility for defining highly representative numerical models that can be used for back analysis purposes or the design of risk mitigation works. One possible drawback of such approaches is that they superimpose structural and topographic data, whose compatibility is not independent of the mechanical behaviour of the rock mass. In fact, the initial geometry depends on the (usually complex) rock slope history, which has a twofold relationship with the whole set of structural and mechanical features of the rock mass. In order to investigate this point, a series of distinct element analyses of an unstable rock face located in Bolzano province is performed. The model is characterised by a very simple geometry, and slope evolution is studied by adopting the strength reduction technique. Structural and mechanical information is obtained from an extensive in situ survey. The aim of the simulations is to show how a model based on the available geomechanical information and a minimum amount of topographic data can be used to reproduce the main topographic features of the rock slope, and to perform a back analysis of a selected case history. [ABSTRACT FROM AUTHOR]

Rockslides are a common and devastating problem affecting mining and other engineering activities all over the world; consequently, there have been many studies into their prediction and prevention. This study focused on a recent rockslide in an open-pit mine in Liaoning Province, China. The stability of the rock slope under excavation and rainfall conditions was monitored using an efficient real-time monitoring system. A further numerical analysis was performed using the finite element method with Lagrangian integration points (FEMLIP), and two forms of the normalized global second-order work were calculated to analyze the stability of the rock slope. In fact for the future it would be very interesting to compare measurements and simulations in real time, and not only to develop back computations after failure. The numerical results indicate that the rock slope remained stable during excavation, yet lost stability after subsequent rainfall. Water infiltration, along with a major geological discontinuity, degraded the strength of the weak zone and induced the rockslide. The monitoring approach presented its robustness and generality, and was worth being generalized. The numerical approach proposed the evolution of the safety factor, the monitoring data were compared, and the mechanism of the rockslide was determined. It could be used as an assistant tool for disaster prediction. [ABSTRACT FROM AUTHOR]

Abstract The North Nahanni rockslide (volume ~7.6 Mm3), Northwest Territories, Canada was triggered by the M w 6.6 Nahanni earthquake of October 5, 1985; the earthquake was followed by a M w 6.8 earthquake at approximately the same location in December 1985. The landslide occurred in a Palaeozoic carbonate sequence sliding along a thrust fault, which partly follows bedding and partly cuts across bedding in the source rock mass. The sliding surface thus consisted of two planes; the lower plane dipped at 20° while the upper plane dipped at 35°. Tilting table test of block samples from the sliding surface and field-measurements of large-scale sliding surface roughness indicated that the friction angle of the sliding surface was 24°. Two-dimensional (2D) slope stability analysis was performed for the slope before and during the earthquake using a discontinuum numerical technique (the distinct element UDEC code). 2D static slope stability analyses indicate that the simple-structured rock mass was marginally stable for sliding surface friction angles of 24°, and was constrained by the residual shear strength of the pre-sheared fault surface. 2D dynamic analyses of the co-seismic movements are conducted by comparing seismically-induced slope displacements computed in both UDEC and SLAMMER (a sliding-block analysis using real earthquake ground motions records of the December 1985 Nahanni earthquake). Both results are in good agreement. The dynamic analysis indicates that the slope becomes unstable for given seismic inputs that correspond closely to those estimated for the October earthquake at a friction angle of 24° for the sliding surface indicating that co-seismic rock slope movement was only possible on low-friction pre-sheared surfaces at residual strength. It also showed that the deformation behavior of the North Nahanni rock masses was dependent on the frequency of the seismic signals. Because the static slope stability analysis showed that the slope was close to instability prior to seismic shaking, the October 1985 Nahanni earthquake operated as a trigger event that accelerated the occurrence of the slide. Highlights • First numerical analysis of earthquake-triggered 1985 Nahanni rockslide • Bi-linear sliding surface corresponds to fault surface in a sedimentary rock mass. • UDEC used for high-resolution static and dynamic slope stability analysis. • Static and dynamic stability constrained by residual strength on pre-sheared sliding surface. • Slope became unstable for seismic inputs that correspond to triggering earthquake. [ABSTRACT FROM AUTHOR]

Abstract The significance of otherwise not frequently applied seismic methods in area of open pits increases by occurrence of unpredictable phenomena threatening the deposit during mining operation. Recognizing natural hazards as rockslide, its arrangement and examination of its formation may prevent the otherwise negative impact on economy of the mining and the mining safety. In this paper synthetic methodological approach including application of seismic refraction, seismic tomography, ground vibration monitoring and geological documentation in dolomite open pit Kraľovany-Rieka (Western Carpathians, Slovakia), where large rockslide covering area of 96,952 m2(Šimeková etal., 2013) evolved, is presented. Four 138 m long profiles were measured using Terraloc Mk8 24 channel seismograph with 10 Hz vertical geophones and geophone offset 6 m and processed by ReflexW Sandmeier scientific software. Seismic velocities and frequencies were during two blasts measured by three-channelled seismographs -UVS 1504, Vibraloc and VMS 2000 MP seismograph at four fixed standpoints to derive the ground transmission coefficient K, referring about the changes of the physical characteristics of the rock environment (Bongiovanni etal., 1991). Geological documentation included mapping and description of the basic lithological units. Results of the methods were integrated into the final model constructed by the Petrel modeling software. The case study revealed complicated geological-structural composition of the area with basement from granodiorites passing upward into thick-bedded carbonates, which are locally covered by Quaternary deposits. Primary factor influencing the rockslide triggering by steep inclination of the basement and faults formation is tectonics. Dense spatial distribution of two fault systems caused a segmentation of the carbonates into several, independently moving blocks. Further agents weakening the rock mass stability were climatic conditions and additional mining activity contributing to gravity driven independent movement of blocks. Seismic refraction and seismic tomography proved as valuable method for geological and structural reconstructions of the open pit and rockslide that are necessary preconditions for the rockslide movement prediction and suggestions of the effective landslide control. [ABSTRACT FROM AUTHOR]

Oversteepened valley walls in western Norway have high recurrences of Holocene rock-slope failure activity causing significant risk to communities and infrastructure. Deposits from six to nine catastrophic rock-slope failure (CRSF) events are preserved at the base of the Mannen rock-slope instability in the Romsdal Valley, western Norway. The timing of these CRSF events was determined by terrestrial cosmogenic nuclide dating and relative chronology due to mapping Quaternary deposits. The stratigraphical chronology indicates that three of the CRSF events occurred between 12 and 10 ka, during regional deglaciation. Congruent with previous investigations, these events are attributed to the debuttressing effect experienced by steep slopes following deglaciation, during a period of paraglacial relaxation. The remaining three to six CRSF events cluster at 4.9 ± 0.6 ka (based on 10 cosmogenic 10Be samples from boulders). CRSF events during this later period are ascribed to climatic changes at the end of the Holocene thermal optimum, including increased precipitation rates, high air temperatures and the associated degradation of permafrost in rock-slope faces. Geomorphological mapping and sedimentological analyses further permit the contextualisation of these deposits within the overall sequence of post-glacial fjord-valley infilling. In the light of contemporary climate change, the relationship between CRSF frequency, precipitation, air temperature and permafrost degradation may be of interest to others working or operating in comparable settings. [ABSTRACT FROM AUTHOR]

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