Mass Failure Research Articles

Level of Knowledge Awareness and Use of Planning as Writing Strategy by EFL International Students in UUM English Intensive Course

<em>Malaysian English Language Curriculum makes it compulsory for every newly intake student to master and pass the English Writing Tasks (EWT) as among the basic skills in the language learning processes. However, most of the English Foreign Language (EFL) international students face difficulties with the EWT during the English Intensive Course (EIC) leading to consistent mass failures. The possible reasons of these failures could be due to the neglect of the writing strategies. Hence, the central focus of this paper is to identify and determine the EFL international students’ level of awareness and the use of planning as writing strategy before writing English essays. To this end, convenient purposive sampling strategy was used where 50 EFL (postgraduate and undergraduate) international students drawn from Universiti Utara Malaysian EIC program were selected and administered Writing Strategy Questionnaires (WSQ). The participants hailed from various countries who used and learned English as a foreign language, namely; Jordan, Iraq, Saudi Arabia, Libya, Palestine among others. The data were analyzed using SPSS. The findings revealed proportionate disparity between the EFL students that use planning strategy before starting writing English essays (usually true = 28%) with those that do not (usually not true = 28%). In terms of Revising Requirement for writing process before one start writing an essay in English, the findings revealed validity (40%) of participants’ responses at 82% cumulative. This is followed by “somewhat true” responses at 24% and 42% cumulative. These imply the EFL international students’ reasonable use of planning and having knowledge awareness of writing strategy</em>

Riverbank Stability Assessment under River Water Level Changes and Hydraulic Erosion

The dominant mechanism of riverbank cantilever failure is soil erosion of the bank toe and near bank zone. This paper demonstrates that the shape of the riverbank cantilever failure depends on the properties of the soil and the fluctuation of the river water level (RWL). With a stable RWL, a riverbank with higher resistance force leads to failure with larger and deeper overhang erosion width. When RWL rises, a less cohesive soil bank will be eroded over a larger width and riverbank failure will occur earlier. With a low rate of rising RWL, riverbank failure may happen in a type of mass failure. With a high rate of rising RWL, a riverbank will fail in a type of overhang riverbank failure, with the soil erosion rate being the main affected factor.

Numerical simulation of the tsunamis generated by the Sciara del Fuoco landslides (Stromboli Island, Italy)

Stromboli volcano (Aeolian Arc, Italy) experiences many mass failures along the Sciara del Fuoco (SdF) scar, which frequently trigger tsunamis of various sizes. In this work, we simulate tsunami waves generated by landslides occurring in the SdF through numerical simulations carried out in two steps: (i) the tsunami triggering, wave propagation and the effects on Stromboli are simulated using the 3D non-hydrostatic model NHWAVE; (ii) generated train waves are then input into the 2D Boussinesq model FUNWAVE-TVD to simulate wave propagation in the Southern Tyrrhenian Sea (STS). We simulated the following scenarios: (i) the tsunami runup, inland inundation and wave propagation at Stromboli triggered by submarine landslides with volumes of 7.1, 11.8, 17.6 and 23.5 × 106 m3 and subaerial landslides with volumes of 4.7, 7.1, 11.8 and 35.3 × 106 m3; (ii) tsunami propagation in the STS triggered by submarine landslides with volumes of 11.8 and 17.6 × 106 m3 and by subaerial landslides with volumes of 7.1 and 35.3 × 106 m3. We estimate that the damages of the last relevant tsunami at Stromboli, which occurred in 2002, could have been generated either by a subaqueous failure of about 17.6-23.5 × 106 m3 along the SdF or/and a subaerial failure of about 4.7-7.1 × 106 m3. The coasts most affected by this phenomenon are not necessarily located near the failure, because the bathymetry and topography can dramatically increase the waves heights locally. Tsunami waves are able to reach the first Stromboli populated beaches in just over 1 minute and the harbour in less than 7 minutes. After about 30 minutes the whole Aeolian Arc would be impacted by maximum tsunami waves. After 1 hour and 20 minutes, waves would encompass the whole STS arriving at Capri.

Changes in particle size distribution of suspended sediment affected by gravity erosion: a field study on steep loess slopes

Gravity erosion (mass movement) generates an enormous volume of sediments on steep slopes throughout the world, yet its effect on the particle size distribution of suspended sediments (PSDSS) remains poorly understood. The objective of this study is to quantify the effects of gravity erosion on soil loss, especially the changes of particle size distribution of the suspended sediment. In this study, experiments were conducted in a field mobile laboratory in which mass movements were triggered on steep slopes under simulated rainfall. During the experiments, water-sediment samples were collected in polyethylene bottles directly from the gully and channel flows before and during the mass movements. The volumes of each mass failure during and 20 min after the rainfalls were measured by a topography meter. The particle fractions of the samples were analyzed by combining the sieving and photoelectric sedimentometer techniques. A suite of indexes such as median sediment size (d50), sediment heterogeneity (H), fractal dimension (D), and enrichment/dilution ratio (Red) were then used to evaluate the effect of mass movement on PSDSS. (1) Gravity erosion had a significant influence on PSDSS. After the mass movements occurred, the proportion of sand-sized particles was decreased from 71 to 51%, whereas the proportions of clay and silt were increased from 1 to 7% and 28 to 42%, respectively. (2) The d50, H, and D were significantly correlated with slope failures. The d50 was decreased from 0.084 to 0.051 mm, whereas the H and D were increased from 5.6 to 26.8 and from 2.60 to 2.78, respectively. This implies that mass movements make the PSDSS more nonuniform and irregular. (3) The suspended sediment tended to be enriched in the silt and clay fractions and diluted in the sand fractions after mass movements. Reds for clay, slit, and sand fractions were 13.9, 1.4, and 0.7 respectively. The changes of PSDSS after mass movements reflected a combined complex effect of soil sources, erosion types, selective detachment, and deposition processes. Mass movements led to a drastic increase of sediment concentration and the enrichment of fine particles, which developed into hyperconcentrated flows.

Prediction of a multi-hazard chain by an integrated numerical simulation approach: the Baige landslide, Jinsha River, China

Successive major landslides during October and November 2018 in Baige village, eastern Tibet, dammed the Jinsha River on two occasions, and the subsequent dam breaches instigated a multi-hazard chain that flooded many towns downstream. Analysis of high-resolution aerial images and field investigations unveiled three potentially unstable rock mass clusters in the source area of the landslides, suggesting possible future failures with potential for river-damming and flooding. In order to evaluate and understand the disaster chain effect linked to the potentially unstable rock mass, we systematically studied the multi-hazard scenarios through an integrated numerical modelling approach. Our model begins with an evaluation of the probability of landslide failure, including runout and river damming, and then addresses the dam breach and resultant flood—hence simulating and visualising an entire disaster chain. The model parameters were calibrated using empirical data from the two Baige landslides. Then, we predict the future cascading hazards via seven scenarios according to all possible combinations of potential rock mass failure. For each scenario, the landslide runouts, dam-breaching, and flooding are numerically simulated with full consideration of uncertainties among the model input parameters. The maximum dam breach flood extent, depth, velocity, and peak arrival time are predicted at sequential sites downstream. As a first attempt to simulate the full spectrum of a landslide-induced multi-hazard chain, our study provides insights and substantiates the value provided by multi-hazard modelling. The integrated approach described here can be applied to similar landslide-induced chains of hazards in other regions.

Mechanisms of riverbank failure and channel instability on the Nkisi River, Southeast Nigeria

Sedimentation hazards pose several geoenvironmental problems in active alpine regions and fluvio-deltaic environments. Therefore, this research seeks quantitative knowledge of the mechanisms that trigger riverbank erosion which result in high volumes of sediment yield in the downstream reaches of the Nkisi River. Study of the mechanisms of mass wasting of the riverbanks was motivated by the high rate of siltation and accretion that are currently occurring at the mouth of the Nkisi River, occupying a total surface area of about 40,000 m2. Many riverbank stability and erosion assessment studies have been done using a wide range of geomorphometric and geotechnical analyses which consider the shear strength of the bank materials in relation to the geomorphometric characteristics of the riverbanks. With this insight, this research focuses on investigating the potential causes of riverbank retreat on the river, with particular interest on the effects of soil properties in triggering mass failures. Field surveys and laboratory investigations, coupled with Bank Erosion Hazard Index (BEHI) and Bank Stability and Toe Erosion Model (BSTEM) characterized the riverbanks as unstable and conditionally stable, revealing a potentially high rate of sediment loading from the composite banks, with a factor of safety that varies from 0.76 to 1.04.

Sedimentology, structure, and age of the Wide Bay Canyon submarine landslide on the southeast Australian continental slope

Sedimentological analysis and radiocarbon dating of three marine sediment cores collected from the upper continental slope offshore from Fraser Island, Queensland, Australia, indicate the region is dynamic and provide strong evidence for mass movement processes occurring during the Late Pleistocene and Holocene. Two cores were collected within the Wide Bay Canyon submarine landslide scar with a third collected on the adjacent open slope. All three cores present intraformational, mud-clast conglomerates, interpreted to be debris flow deposits comprised of sub-angular to rounded, pebbled and cobble-sized clasts of the hemipelagic muds that typically accumulate in this area. One within-slide core and the open slope core also present coarse-grained, poorly sorted, unconsolidated sand layers that are interpreted to be grain flow deposits derived from continental shelf sands that were driven over the continental shelf edge by the East Australia Current during the Last Glacial Maximum. Radiocarbon dating of unconformities identified in the Wide Bay Canyon slide scar cores indicates that abrasion and sediment removal during the emplacement of debris flows occurred during several separate events prior to ~35.1 cal. yr. BP. The sand layers interpreted to be grain flow deposits contain Late Pleistocene age material that was probably re-deposited during the sea level low-stand associated with the Last Glacial Maximum. Consideration of the debris flow ages in the context of ages reported for similar materials and other landslide deposits recorded on the South-eastern Australian Continental Margin supports the previously advanced hypothesis that rare, moderate to large, intraplate earthquakes are a likely triggering mechanism for submarine landslides and/or mass failure events on the South-eastern Australian Continental Margin.

Expert consensus on bone repair strategies for osteoporotic fractures in China

Osteoporotic fracture is characterized by poor bone mass, slow repair, weak stability and high failure rate of internal fixation, often accompanied with bone defects to varied degrees. Clinically, the common defect sites are proximal humerus, distal radius, tibia plateau, calcaneus and spine. At present, autogenous, allogenic and various bone substitutes are used for repair. Based on the epidemiology of osteoporotic fracture, literature review, and field research, this consensus outlines the characteristics of bone defects, bone repair materials, bone repair strategies at common sites and the application of rehabilitation aids. It is expected to improve the prognosis of osteoporotic fracture and promote the clinical standardization process of bone defect repair of osteoporotic fracture. Key words: Osteoporotic fractures; Repair surgery; Bone defect

A true triaxial geomechanical model test apparatus for studying the precursory information of water inrush from impermeable rock mass failure

To study the precursory information of water inrush from impermeable rock mass failure, a true triaxial geomechanical model test apparatus was developed. The test apparatus designed is 5.5 m in length, 4.0 m in width and 2.5 m in height. It is mainly composed of a steel frame system, a hydraulic control system, a water pressure loading system and a data monitoring system. The main feature of the true triaxial model test apparatus is its ability to apply high, uniform compressive loads in all three principal directions to perform tests under true triaxial static loading conditions. The apparatus can also be used to study the solid-fluid interaction of the surrounding rock mass and water. A test sample can be placed into and removed from the apparatus automatically and conveniently by hydraulic control software. A model test of the water inrush in the Xiema Tunnel, which is located in Chongqing, China, was carried out by using this apparatus. The size of the experimental sample was 1500 × 1000 × 1000 mm. The variations in displacement, stress and seepage pressure were investigated. The test results indicate that the apparatus is stable and reliable.

Internal tsunami waves transport sediment released by underwater landslides

Accelerated by gravity, submarine landslides transfer energy to the marine environment, most notably leading to catastrophic tsunamis. While tsunamis are thought to use less than 15% of the total energy released by landslides, little is known about subsurface processes comprising the rest of their energy budgets. Here, we analyze the first set of observations depicting a lake’s interior response to underwater landslides and find that sediment transport is modulated by baroclinic waves that propagate along vertical gradients in temperature and sediment concentration. When traveling along a shallow thermocline, these waves can reach past topographic features that bound turbidity currents and thus expand the influence area of underwater landslides. With order of magnitude calculations, we estimate that observed thermocline internal waves received roughly 0.7% of available landslide energy and infer their contribution to homogenize the lake’s thermodynamical properties by means of turbulent mixing. Lastly, we show that landslides in our data set modified the lake’s intrinsic dynamical modes and thus had a permanent impact on its circulation. This suggests that measurements of subsurface wave propagation are sufficient to diagnose bathymetric transformations. Our experiment constitutes the first direct observation of both internal tsunami waves and turbidity current reflection. Moreover, it demonstrates that background density stratification has a significant effect on the transport of sediment after submarine landslides and provides a valuable reference for numerical models that simulate submarine mass failures.

Deepwater to fluvio-deltaic stratigraphic evolution of a deglaciated depocenter: The early Permian Rio do Sul and Rio Bonito formations, southern Brazil

This paper describes facies relationships and stratigraphic architecture of early Permian deglacial deepwater to fluvio-deltaic deposits exposed in the eastern border of the Paraná Basin, southern Brazil. The studied succession is located in the Rio do Sul depocenter and comprises an upward transition between the topmost interval of the Itararé Group (Rio do Sul Formation) and the lowermost unit of the Rio Bonito Formation (Triunfo Member). Geological mapping and facies analysis allowed the recognition of the following facies associations, vertically stacked: thin and thick-bedded turbidites, hyperconcentrated and concentrated density-flow deposits (hyperpycnites), mass-transport deposits, fine-grained heterolithic beds of prodelta, delta-front, shoreface and delta-plain deposits, as well as fluvial beds resting on incised valleys. The stratigraphic analysis through the interpretation of the facies associations, stacking pattern and paleocurrent dispersal trends were enough to define the clinoform stratigraphic architecture, composing a progradational-aggradational pattern. The paleoflows for all facies associations show a main trend towards the south-southwest. In this context, hyperpycnal beds can represent a glacial source from the northeast, because of striated and faceted clasts immersed in the conglomeratic facies, whereas turbidites have been understood as the products of their dilution. Likewise, mass-transport deposits are related to the collapse of the shelf-margin delta, represented by allochthonous blocks composed of deltaic beds within the mass-flow diamictites. Thus, these mass-transport deposits do not evolve downslope to turbidity currents. This configuration was likely for building the relief of the slope system, probably a shelf-edge delta susceptible to mass failure. Paleo-ice flows towards SW recorded in the Rio do Sul Formation, genetic related to fluvio-deltaic deposits of Rio Bonito Formation, highlight the scenario of final stages of the Late Paleozoic Ice Age in the SW of Gondwana and support the previous researches which point to the presence of diachronous ice-spreading centers from paleohighs.

Evolution of Debris‐Flow Initiation Mechanisms and Sediment Sources During a Sequence of Postwildfire Rainstorms

Wildfire alters vegetation cover and soil hydrologic properties, substantially increasing the likelihood of debris flows in steep watersheds. Our understanding of initiation mechanisms of postwildfire debris flows is limited, in part, by a lack of direct observations and measurements. In particular, there is a need to understand temporal variations in debris‐flow likelihood following wildfire and how those variations relate to wildfire‐induced hydrologic and geomorphic changes. In this study, we use a combination of in situ measurements, hydrologic monitoring equipment, and numerical modeling to assess the impact of wildfire‐induced hydrologic and geomorphic changes on debris‐flow initiation during seven postwildfire rainstorms. We predict the impact of hillslope erosion on debris‐flow initiation by combining terrestrial laser scanning surveys of a hillslope burned during the 2016 Fish Fire with numerical modeling of sediment transport throughout a 0.12‐km2 basin in southern California. We use measurements of sediment thickness within the channel to constrain numerical experiments and to assess the role of channel sediment supply on debris‐flow initiation. Results demonstrate that debris flows initiated during rainstorms where hillslopes contributed minimally to the event sediment yield and suggest that large inputs of sediment from rill and gully networks are not essential for runoff‐generated debris flows. Simulations suggest that both the gradual entrainment of sediment and the mass failure of channel bed sediment can increase sediment concentration to levels associated with debris flows. Finally, postwildfire debris‐flow initiation appears closely linked to the same rainfall intensity‐duration threshold despite temporal changes in the sediment source, initiation processes, and hydraulic roughness.

Challenges Facing Teaching and Learning of English Language in Public Secondary Schools in Enugu State Nigeria

English language is the official language in Nigeria. The teaching and learning of English is important for Nigerian students especially at the secondary school level. However, several factors have led to mass failure of the subject by students at this level. This study sought to examine the challenges to effective teaching and learning of English language in secondary schools in Enugu state. The specific objectives included identifying the government factors; student based factors; teachers’ related factors and school administration/management based factors that contribute to the challenges. The study adopted survey research method and hundred questionnaires were used. Data were analysed with the use of descriptive statistics (percentages and mean). Respondents agreed that government based challenges included heavy workload and curriculum (=2.9) and do not provide sufficient learning materials (=2.6). The students based challenges included anxiety and fear for the subject (=2.7) and scarce English practice (=2.7). Teachers based challenges were not good qualification (=2.9) and lack of adequate teaching methods and instructional materials (=2.8). The school administration based factors included poor planning of learning structures (=2.9) and provision of malfunctioning or inappropriate curriculum (=2.9). Government is recommended to provide less workload, relevant curriculum, sufficient learning materials and adequate training for the teachers among others.

Identifying post-earthquake debris flow hazard using Massflow

Catastrophic debris flows are common after large earthquakes and pose a significant risk for recovering communities. The depositional volume of these large debris flows is often much greater than the initiation volume, suggesting that bulking of the flow plays an important role in determining their volume, speed, and runout distance. Observations from recent earthquakes have driven progress in understanding the relationship between triggering rainfall events and the timing of post-earthquake debris flows. However, we lack an adequate mechanism for quantifying bulking and applying it within a hazard context. Here we apply a 2D dynamic debris flow model (Massflow) that incorporates a process-based expression of basal entrainment to understand how debris flow bulking may occur within post-earthquake catchments and develop hazard maps. Focussing on catchments in the epicentral area of the 2008 Mw 7.9 Wenchuan Earthquake, we first parameterised the model based on a large debris flow that occurred within the Hongchun catchment, before applying the calibrated model to adjoining catchments. A model sensitivity analysis identified three main controls on debris flow bulking; the saturation level of entrainable material along the flow pathway, and the size and position of initial mass failures. The model demonstrates that the difference between small and very large debris flows occur across a narrow range of pore-water ratios (λ). Below λ = 0.65 flows falter at the base of hillslopes and come to rest in the valley bottom, above λ = 0.70 they build sufficient mass and momentum to sustain channelised flow and transport large volumes of material beyond the valley confines. Finally, we applied the model across different catchments to develop hazard maps that demonstrate the utility of Massflow in post-earthquake planning within the Wenchuan epicentral region.

Large-scale mass wasting on the Miocene continental margin of western India

Abstract A giant mass-transport complex was recently discovered in the eastern Arabian Sea, exceeding in volume all but one other known complex on passive margins worldwide. The complex, named the Nataraja Slide, was drilled by International Ocean Discovery Program (IODP) Expedition 355 in two locations where it is ∼300 m (Site U1456) and ∼200 m thick (Site U1457). The top of this mass-transport complex is defined by the presence of both reworked microfossil assemblages and deformation structures, such as folding and faulting. The deposit consists of two main phases of mass wasting, each consisting of smaller pulses, with generally fining-upward cycles, all emplaced just prior to 10.8 Ma based on biostratigraphy. The base of the deposit at each site is composed largely of matrix-supported carbonate breccia that is interpreted as the product of debris-flows. In the first phase, these breccias alternate with well-sorted calcarenites deposited from a high-energy current, coherent limestone blocks that are derived directly from the Indian continental margin, and a few clastic mudstone beds. In the second phase, at the top of the deposit, muddy turbidites dominate and become increasingly more siliciclastic. At Site U1456, where both phases are seen, a 20-m section of hemipelagic mudstone is present, overlain by a ∼40-m-thick section of calcarenite and slumped interbedded mud and siltstone. Bulk sediment geochemistry, heavy-mineral analysis, clay mineralogy, isotope geochemistry, and detrital zircon U-Pb ages constrain the provenance of the clastic, muddy material to being reworked, Indus-derived sediment, with input from western Indian rivers (e.g., Narmada and Tapti rivers), and some material from the Deccan Traps. The carbonate blocks found within the breccias are shallow-water limestones from the outer western Indian continental shelf, which was oversteepened from enhanced clastic sediment delivery during the mid-Miocene. The final emplacement of the material was likely related to seismicity as there are modern intraplate earthquakes close to the source of the slide. Although we hypothesize that this area is at low risk for future mass wasting events, it should be noted that other oversteepened continental margins around the world could be at risk for mass failure as large as the Nataraja Slide.

122 Weakness in a Patient with a Mediastinal Mass and Acute Renal Failure

122 Weakness in a Patient with a Mediastinal Mass and Acute Renal Failure

Probabilistic Landslide-Generated Tsunamis in the Indus Canyon, NW Indian Ocean, Using Statistical Emulation

The Indus Canyon in the northwestern Indian Ocean has been reported to be the site of numerous submarine mass failures in the past. This study is the first to investigate potential tsunami hazards associated with such mass failures in this region. We employed statistical emulation, i.e. surrogate modelling, to efficiently quantify uncertainties associated with slump-generated tsunamis at the slopes of the canyon. We simulated 60 slump scenarios with thickness of 100–300 m, width of 6–10.5 km, travel distances of 500–2000 m and submergence depth of 250–450 m. These scenarios were then used to train the emulator and predict 500,000 trial scenarios in order to study probabilistically the tsunami hazard over the near field. Due to narrow–deep canyon walls and the shallow continental shelf in the adjacent regions (<100 m water depth), the tsunami propagation has a unique pattern as an ellipse stretched in the NE–SW direction. The results show that the most likely tsunami amplitudes and velocities are approximately 0.2–1.0 m and 2.5–13 m/s, respectively, which can potentially impact vessels and maritime facilities. We demonstrate that the emulator-based approach is an important tool for probabilistic hazard analysis since it can generate thousands of tsunami scenarios in few seconds, compared to days of computations on High Performance Computing facilities for a single run of the dispersive tsunami solver that we use here.

Effect of kinematic fault rupture process on tsunami propagation

The scope of this study is to investigate the effect of the kinematic rupture process on tsunami propagation and corresponding tsunami hazards in coastal regions. It is significant for the tsunageneric earthquakes of long fault length and subsequent long duration of the fault rupture in the strike direction. Most previous studies on the tsunami hazard assessments of the Manila Trench did not consider the effect of the rupture process of huge plates. The movements of the seabed near the earthquake source are calculated by Okada model. The free surface elevation triggered by the seafloor motion is modeled by the nonlinear shallow water equations. The 2004 Indian Ocean tsunami and the 2011 Japan Tohoku tsunami are used to validate the numerical model by comparing with measurement data. The numerical experiments of the tsunami propagation for the cases of different source rupture velocities in uniform depth and continental shelf are carried out to understand the mechanism of the changes of the tsunami arrival time and the tsunami amplitude due to the kinematic rupture process. Stimulated by the long duration of plate motion of 2004 Indian Ocean tsunami, we propose several typical patterns of the rupture process of the long fault of the Manila Trench and analyze quantitatively on the role of the uncertain rupture process of tectonics source in tsunami propagation in the South China Sea. Our results have highlighted that the slow rupture velocity will remarkable affect the tsunami arrival time and maximum amplitude in the South China Sea, comparing to the instantaneous rupture. It is suggested that the rupture process is essential for assessments of the tsunami hazards generated by submarine mass failure with extreme long earthquake rupture source.

Generalised Analytical Models for the Strength of the Inclined as well as the Flat Coal Pillars using Rock Mass Failure Criterion

The assessment of the strength of the coal pillars is essential for the safe extraction of the coal seam. All the pillar strength formulae used worldwide are developed for the flat coal pillars. Therefore, their adoption in evaluating the strength of the inclined coal pillars may endanger the workings of the inclined coal seams. The strength of an inclined coal pillar should be estimated by considering the inclination of the coal seam and its associated behaviour, because the shearing effect along the true dip aggravates the instability of the inclined coal pillars. In this paper, generalised analytical solutions have been developed to estimate the strength of the coal pillars which can be applied for both the inclined and flat coal pillars. The mathematical models are derived to obtain the confining stress in the coal pillar and the corresponding peak stress at the time of its failure using a rock mass failure criterion. The mathematical expressions are also developed for the stress distribution over the pillar considering the increase of the shearing effect with the dip of the coal seam. The Mohr–Coulomb criterion is considered for the shear characteristics at the interfaces of pillar–floor and pillar–roof. The asymmetrical stress distribution and failure along the dip-rise and the strike directions of the inclined coal pillars are addressed in this study. The concept of the confined core and three-dimensional stress distribution over the coal pillar are used to derive the strength formulae for the square, rectangular, and very long pillars. The performance of the derived strength formulae is assessed by the stable and failed cases of the flat and the inclined coal pillars. It is observed that all the inclined and flat coal pillars cases are correctly predicted by the derived generalised strength formulae. According to the derived strength formulae, the strength of the inclined coal pillar decreases with the increase of the inclination of the coal pillar. This paper also describes the variation of the strength of the inclined coal pillars with respect to the coal seam inclinations and the frictional properties of the contact planes for the different width-to-height ratios.

Debris flows in southeast Australia linked to drought, wildfire, and the El Niño–Southern Oscillation

Between 2003 and 2013, drought, large wildfires, and record-breaking rainfall contributed to debris flows in southeast Australia that appear to be unprecedented in spatial extent and density in historical records. Here, we used a debris-flow inventory from this period of dry and wet extremes to examine the processes and climatic controls underlying the regionwide debris-flow response. Results reveal shallow landslides and surface runoff as two distinct initiation mechanisms, linked to different geologic settings and contrasting hydroclimatic conditions. Landslide-generated debris flows occurred in sandy soils, independent of past fires, and were tightly controlled by extreme rainfall causing saturation and mass failure during La Nina periods. In contrast, runoff-generated debris flows occurred in clay-rich soils from short and intense rainstorms after wildfires in dry conditions, often associated with El Nino. Thus, it appears that both ends of the wet and dry climate extremes produce the same general geomorphic response, debris flows, but in different areas and by different initiation processes. Debris-flow activity is therefore at a maximum when amplitude and frequency of climate oscillations are large. Debris flows in southeast Australia are likely to become more frequent and widespread as wildfire activity and rainfall intensity are predicted to increase.