M3 Of Debris Research Articles

Deformation and Failure Process of Slope Caused by Underground Mining: A Case Study of Pusa Collapse in Nayong County, Guizhou Province, China

Pusa village is located in the karst mountain area of Nayong County, Guizhou Province, China. Laoyingyan mountain rock is gently dipping, the upper part consists of hard rock formations, and the lower part is made up of soft rock composed of 3 coal seams. On August 28, 2017, a massive landslide occurred in this area, resulting in 82,3000 m3 of debris, which resulted in significant casualties and brought up the malaise in society. In this paper, the geological conditions and long-term mining activities in the study area are analyzed by field investigation. The base friction tests and numerical models are used to simulate and analyze the failure and deformation process of Pusa collapse to accommodate the research on the deformation and failure mechanism of the slope and provide better prevention and treatment suggestions. The results show that the Pusa collapse can mainly be attributed to unique geological conditions, underground mining activities, and the topography of the slope. The intensified mining activities promoted the development of fractures and cracks in the slope, resulting in unstable upper slopes. The failure process of the Pusa collapse can be summarized into four-stage: the development of goaves roof deformation, the crest of the slope cracks, intensification of deformation, and occurrence of collapse. The upper slope with high strength rock developed crack-toppling failure. Meanwhile, the upper slope with low strength rock developed subside-crack-sliding failure, and those two failures together contributed to the mechanism of Pusa collapse. Slope deformation and failure mechanism can be summarized as subside-crack-toppling-shear sliding type.

Initiation mechanisms and dynamics of a debris flow originated from debris-ice mixture slope failure in southeast Tibet, China

Glacial debris flows are a common catastrophic hazard in alpine regions due to glacier recession and permafrost thawing. They are frequently triggered by heavy rainfall and outburst floods. To date, studies on debris flows originated from debris-ice mixture slope failures triggered by glacier melting in low-intensity rainfall conditions are still limited. In this study, a typical glacial debris flow that occurred in September 2020 on the west side of Namcha Barwa in southeast Tibet, China, is taken as a benchmark to reveal the initiation mechanisms and dynamics of debris-ice landslide-debris flow hazard chains. The flow discharge, erosion, entrainment, deposition, and dynamic process of the debris flow are evidenced by both field investigations and numerical simulations with a single-phase cell-based simulation program, Erosion–Deposition Debris Flow Analysis (EDDA) (Chen and Zhang, 2015) and a multi-phase flow model r.avaflow (Pudasaini and Mergili, 2019). This hazard chain was originated from a debris-ice mixture slope failure with a volume of 1.14× 106 m3 in a temperate area under little rainfall. The mobile mixture entrained saturated moraines and water in the ravine channel and rapidly transformed into a viscous debris flow, traveling about 9.78 km and entraining 50% more materials along the path. The peak discharge and frontal flow velocity at the outlet of the ravine reached 4700 m3/s and 11.4 m/s, respectively. About 3.75× 105 m3 of debris deposited on the riverbed and partially blocked the Yarlung Tsangpo, causing severe damage to local infrastructures. This study provides a scientific basis for understanding the evolution process of a debris-ice landslide-debris flow hazard chain and for minimizing its adverse impact on key infrastructures in the region.

Appropriate management of earthquake generated waste: Lessons from the 2016 earthquake in Ecuador

The earthquake that hit Ecuador on April 16th, 2016, generated immense devastation to the province of Manabi and created large volumes of debris and waste. This study aims to analyze the lack of a pre-disaster plan that affected the 2016 earthquake waste management. Without an acceptable method, the maker-decisions that faced proximate and fundamental problems fell into turmoil which consequences the disposal of debris confined in makeshift and a low rate of recovery of recycling materials. Data was collected through surveys addresses to total medium and small-sized scrap businesses (n=22) in Portoviejo city in October 2019. In addition, statistical information from public and private agencies was obtained. The results of this study showed limitations in the 2016 earthquake waste management process such as lack of landfill areas, lack of temporary and final disposal sites and organizational limitations in the recycling process and material recovery. In addition, 2016 earthquake generated approximately 7,561,219.81 m3 of debris in Manabí, of which 6.9% was in Portoviejo. In the first month post-earthquake, 13,500,000 kilograms of ordinary and hazardous waste in Portoviejo city were collected, of which 20% was reused or recycled.

Study of dynamic debris impact load on flexible debris-resisting barriers and the dynamic pressure coefficient

The use of steel flexible barriers to mitigate landslide risk on natural hillsides is becoming common in the past decade in Hong Kong. The current design approach for this kind of barrier structure involves the adoption of the hydrodynamic load model to predict dynamic impact forces, followed by non-linear structural analyses of flexible barriers using numerical programs based on the pseudo-static force method. From local design guidelines, the dynamic pressure coefficient, a critical input parameter in the hydrodynamic load model, is taken as 2.0. This empirically considers the effect of impacts from boulders up to 2.0 m in diameter. With a view to rationalising the design approach, a series of physical impact tests and numerical analyses was conducted to investigate the dynamic debris impact on flexible barriers and the resulting barrier response. The physical impact tests involved up to 9 m3 of debris resisted by a 1.5 m high steel ring-net barrier. The tests were conducted in the 28 m long large-scale flume facility at the Kadoorie Centre in Hong Kong. Numerical modelling using computer programs LS-DYNA and NIDA-MNN was conducted to analyse the dynamic response of flexible barriers with different structural forms. The study aims to evaluate the dynamic pressure coefficient and to verify the current design approach based on the suggested dynamic pressure coefficient from this study. Results indicate that a dynamic pressure coefficient of 1.0 is, in general, appropriate for design purposes if the debris comprises primarily water and fine-grained particles.

Mass-wasting deposits in the Domuyo Volcanic Center, northern Neuquén Andes (Argentina): An analysis of the controlling factors

A high-mobility mass movement deposit was identified along the Turbio river, which drains the north-facing hillslope of the Domuyo Volcano, in the northern Neuquén Andes. Multiple satellite images and aerial photograph images pre- and post-mass movement have been examined to study its general features and to narrow the time window of the event. Results suggest that, in 1997, a volume of approximately 0.8 × 106 m3 of debris slid nearly 10 km descending a vertical range of ~1400 m and covering a minimum area of 1.5 × 105 m2. The 1997 autumn-winter period was characterized by unusually heavy precipitation in the area (the largest value of precipitation registered in the last 30 years), which was related to a major El Niño Southern Oscillation event. We interpret the deposit as a debris flow event that would have emerged from a moraine whose loose sediments would have set into motion in a context of heavy rainfalls. Furthermore, in the vicinities of the Domuyo Volcano, there is a widespread occurrence of rock avalanches, mostly post-glacial in age, recognized and mapped in this work. Their distribution is coincident with recently published InSAR deformation patterns, which, together with seismic and geophysical data, may be indicating that the volcanic edifice has been subject to inflation processes for at least the last four years. Assuming that similar volcanic unrest episodes occurred in the last thousand years, we can speculate that a volcano-tectonic control could have played a role in the development of these rock avalanches. From there, this work shows that, in a deglacial landscape like the one that defines the Domuyo Volcano area, there are different elements that can act on slope instability. This information intends to be used proactively to advance in the hazard evaluation of these catastrophic processes in the northern Neuquén Andes, a zone with increasing agricultural and tourism activities.

Retrospective analysis of the Pico del Castillo de Vinuesa large historical landslide (Cordillera Iberica, Spain)

The failure mechanism of a large historical landslide that caused the partial destruction of the Pico del Castillo de Vinuesa has been determined and characterized by a multidisciplinary approach. This study combines the application of complementary fields such as geological analyses, field and laboratory tests, geomorphological, geomechanical and hydrogeological characterizations, retrospective mathematical simulations, and absolute dating methods to determine the origin and age of the landslide. The instability event occurred shortly before 1600 BP and mobilized more than 30 million m3 of debris from the competent conglomerate layer that formed the ancient summit. The conglomerate is considered to have slid over a claystone layer dipping 12°, following a translational sliding model. The underlying claystone layer constituted the impervious base of the aquifer formed by the displaced material. The hydrogeological conditions played a key role in the slide by changing the mechanical properties of both the claystone and the conglomerate layers.

Mechanism of the 2019 Yahuokou landslide reactivation in Gansu, China and its causes

In this study, we investigated a recent landslide that occurred in Zhouqu County, China. At 18:00 pm Beijing time on July 19, 2019, the Yahuokou landslide was reactivated. About 3.92 × 106 m3 of debris slumped from the slope, blocking the Minjiang River channel, causing the water level to rise, and disrupting road. Fortunately, there were no injuries. A field survey, remote sensing imaging, borehole core analysis, landslide monitoring, and rainfall data analysis were conducted to examine the geomorphologic and stratigraphic characteristics of the landslide, the reactivation causes, and the dynamic mechanism of the landslide. A model for the reactivation and evolution of the landslide is presented. The field survey of the sliding zone indicates that the landslide has a flow-slide deformation pattern. The landslide mechanism is summarized as follows. Initially, slow plastic flow sliding occurred in the upper sliding body. Then the platform in the middle gentle slope was preloaded by deposits from the upper part failure, resulting in a “cutting and filling” effect. The failure occurred in the form of creep–tension cracks–debris flow–slide. Finally, the block on the lower part slumped. Thus, the upper, middle, and lower parts of the landslide all transferred stress in the same manner, being activated step by step, and slowly slumped into the river.

Direct field observations of massive bedload and debris-flow depositions in open check dams

Sediment detention basins, also called SABO dams, are key facilities in flood protection systems of mountain catchments, specifically in torrents prone to massive bedload transport or debris flows. A better understanding of the processes generating sediment trapping is required to optimize their functioning. Two monitoring stations have been implemented in the French Alps on two torrents: the Manival (Saint-Nazaire-Les-Eymes) and the Claret (Saint-Julien-Mont-Denis). Time-lapse photos show an event depositing 10,000 m3of debris flow in a basin in less than six minutes and several events partially filling the other basin with gravel, impairing its capacity to store debris flows later. After a presentation of the catchments, this paper qualitatively analyzes the dynamics of the depositions. It highlights and stresses the consistency and differences between bedload and debris-flow deposition. Overall, despite clear differences of geomorphic activity, deposits tend to fill the trap basins just enough to enable the sediment transport continuity reestablishment through the basin. The open check dams thus play a role only provided that this continuity precondition is completed. These observations enhance our comprehension of massive sediment trapping in torrents and our capacity to better adjust trap maintenance and design to the objective sought in each site.

Photogrammetric Monitoring of an Artificially Generated Shallow Landslide

AbstractAn artificial rainfall event was applied to a forested slope in Ruedlingen, northern Switzerland. The experiment triggered a landslide which resulted in mobilising about 130 m3 of debris. The event was monitored by a photogrammetric network of four cameras, operating at 5 to 8 frames per second, in order to quantify spatial and temporal changes by tracking tennis balls pegged into the ground. Image measurements were performed using automated image matching methods, implemented through a software package developed in‐house. Three‐dimensional coordinates of the target points were estimated by running a customised type of bundle adjustment, achieving a positioning precision of ± 1·8 cm.

Effects of mass-wasting on the stratigraphic architecture of a fjord-valley fill: Correlation of onshore, shear-wave seismic and marine seismic data at Trondheim, Norway

A combined record of onshore, high-resolution, shear-wave seismic and marine, P-wave seismic data shows the near-shore stratigraphic organisation of a fjord-valley fill at Trondheim, central Norway. The overall stratigraphy shows a typical fjord-valley fill of up to 160m in thickness that is composed of glaciomarine and fjord-marine sediments overlain by deltaic deposits which, in the onshore section, are draped by an anthropogenic fill. An interval characterised by low shear-wave velocities below the onshore, anthropogenic fills is shown by sampled drillings to comprise part clay and part organic deposits. The seismic record reveals evidence of recurrent mass-wasting events that include landslide debris, turbidite deposits and channel features. A chronological framework for the stratigraphy is provided by existing radiocarbon dates for local deglaciation and mass-wasting events. The combined onshore–offshore datasets document the Lateglacial to Holocene development of an emerging fjord and delta system affected by major, mass-wasting events. The architectural development of the younger part of the stratigraphy is interpreted as particularly affected by two, known mass-wasting events each involving several million m3 of debris. A thick layer of debris from a 3500calyr event probably resulted in a blockage of the subaqueous channels, diversion of turbidity currents and deposition of lateral accretion packages, whereby local fjord sedimentation temporarily increased. A 2200calyr event resulted in a sudden reorganisation of the distributary system whereby distal delta sedimentation abruptly shifted north- to northeastwards to an area temporarily subjected to marine erosion during fall of relative sea level. The study adds to the understanding of landslides and low-stiffness zones in the area of importance for near-shore geohazard assessment. The study also provides insight into the stratigraphic variability of fjord-valley fills, and highlights the interplay between fjord marine sedimentation, marine abrasion, delta progradation and mass wasting during late stages of fjord filling.

Physical characteristics and triggering mechanisms of the 2009–2010 landslide crisis at Montagne Pelée volcano, Martinique: implication for erosional processes and debris-flow hazards

Abstract Flank destabilizations are common processes in the life of a volcano. Apart from giant landslides with recurrence times of tens of thousands of years and whose deposits are identified in the bathymetry around the islands, less voluminous but more frequent erosional landslides contribute significantly to the morphological development of the topography. In this paper, we present a detailed description of a landslide sequence that occurred in 2009 and 2010 on the western flank of Montagne Pelée volcano, originating at the Samperre cliff. This sequence is characterized by two main events, in August 2009 and May 2010, and hundreds of smaller collapses. From seismic data and high resolution topographic data from airborne Lidar, collapses are counted and volumes of the main events are estimated. The May 2010 landslide has removed 2.1 millions of m3 of debris, which were subsequently remobilized during several hazardous lahars. The mean rates of erosion deduced from these volumes indicate that this kind of erosional landslide could represent a long term contribution of the same order of magnitude as giant flank collapses. The characterization of the runout of the landslides and of the Samperre cliff slopes provide important information for risk assessment, in particular for the risk of lahars that threaten the population living on the lower slopes.

Lessons from a Flash Flood in Tehran Subway, Iran

On 15 April 2012 at around 13:00 local time, following a heavy rainfall in Tehran, a break in the channel wall of Kan River caused a flash flood in the Tehran metro tunnels. Consequently, line 4 of the metro went out of operation for about two weeks. The flood was running for 30 hours in the metro system so that three stations were flooded causing damage to four trains and 28 wagons. It is estimated that approximately one million cubic meters of water and debris rushed in the metro tunnels through the break. Although this flash flood caused property damage of about $21 million (at the then official exchange rate) to the metro especially its electrical system, fortunately no death and injury ensued. Quick measures were taken to disconnect electricity and evacuate more than 1,500 passengers and staff from the adjacent stations while simultaneously the water was draining. For a few days, more than 10 thousands m3 of debris and precipitants were removed from the stations and trains. Finally, damaged stations were repaired and got back to the operation in 12 days. It was claimed that 2,500 persons worked every day during the response to this disaster. Immediate disconnection of the electricity system prevented electrocutions. Timely emergency evacuation in this event saved hundreds of lives. All trains were stopped in adjacent stations and the passengers were instructed by the staff to safely evacuate the metro. In addition, dwellers near at risk stations were relocated to safe buildings. Here, we wish to address some challenges along with corresponding lessons learned that have a bearing on revisions to the emergency plan of Tehran in general and Tehran's metro in particular. Language: en

The 17 February 2006 Guinsaugon rock slide-debris avalanche, Southern Leyte, Philippines: deposit characteristics and failure mechanism

The Guinsaugon rock slide-debris avalanche was the most catastrophic single landslide event in Philippine history, with 14–18 M m3 of debris instantly burying an entire village. Hummocky topography, pressure ridges and other internal structures suggest that the landslide deposit was emplaced as a debris avalanche and debris flow. Susceptibility to planar and wedge failures as well as to toppling due to rock discontinuities were demonstrated using kinematic analysis and SMR. Limit equilibrium analysis on planar failures yielded factors of safety ranging from 0.8 to 1.5. The study showed that pore pressure on discontinuities had a more significant effect on the slope stability than seismicity. For wedge failures, there is a sudden drop in the factor of safety at pore water pressures of 258–306 kPa. At the site, the pore water pressure may have been as high as 490 kPa. The possibility of such a landslide event in the future is discussed.

Simultaneous monitoring of a collapsing landslide with video cameras

Abstract. Effective countermeasures and risk management to reduce landslide hazards require a full understanding of the processes of collapsing landslides. While the processes are generally estimated from the features of debris deposits after collapse, simultaneous monitoring during collapse provides more insights into the processes. Such monitoring, however, is usually very difficult, because it is rarely possible to predict when a collapse will occur. This study introduces a rare case in which a collapsing landslide (150 m in width and 135 m in height) was filmed with three video cameras in Higashi-Yokoyama, Gifu Prefecture, Japan. The cameras were set up in the front and on the right and left sides of the slide in May 2006, one month after a series of small slope failures in the toe and the formation of cracks on the head indicated that a collapse was imminent. The filmed images showed that the landslide collapse started from rock falls and slope failures occurring mainly around the margin, that is, the head, sides and toe. These rock falls and slope failures, which were individually counted on the screen, increased with time. Analyzing the images, five of the failures were estimated to have each produced more than 1000 m3 of debris, and the landslide collapsed with several surface failures accompanied by a toppling movement. The manner of the collapse suggested that the slip surface initially remained on the upper slope, and then extended down the slope as the excessive internal stress shifted downwards. Image analysis, together with field measurements using a ground-based laser scanner after the collapse, indicated that the landslide produced a total of 50 000 m3 of debris. As described above, simultaneous monitoring provides valuable information about landslide processes. Further development of monitoring techniques will help clarify landslide processes qualitatively as well as quantitatively.

THE FOURTH IN AN OCCASIONAL SERIES OF EARTH PHENOMENA

ABSTRACTThis, the Iargest continental earthquake of the 20th Century, occurred on a low‐angle detachment at the eastern end of the Himalayan mountain arc. Great earthquakes in this region are fundamental forces of erosion: above the c.300X150 km‐long fault rupture, in the steep‐sided valley‐tributaries of the upper Brahmaputra, landslides covered about one third (15, 000 km2) of the surface comprising an estimated 5X1010 m3 of debris, 30 times the volume carried annually by the whole Brahmaputra River.Two English plant‐hunters, Jean and Frank Kingdon‐Ward, with their Assam guides were based in the upper Lohit Valley, just over the Tibetan border with Assam, waiting for an opportunity to ascend to the Alpine pastures.

The 1985 Catastrophic Drainage of a Moraine-Dammed Lake, Khumbu Himal, Nepal: Cause and Consequences

On 4 August 1985 Dig Tsho, a moraine-dammed glacial lake in the Khumbu area of eastern Nepal, burst above Thame. For the region close to the origin of the outbreak the consequences were catastrophic. The destruction of a newly built hydroelectricp ower plant, 14 bridges, about 30 houses, and many hectares of valuable arable land, as well as a heavily damaged trail network, resulted from 5 million m3 of water plummetting down the Bhote Kosi and Dudh Kosi valleys. The breaching of the moraine was triggered by wave action following an ice avalanche of 150,000 m3 into the lake. The surge had a peak discharge of 1,600 m3/sec; 3 million m3 of debris were moved within a distance of less than 40 km. However, only 10-15 percent of the material left the region as suspended load. The potential hazard of glacial lakes persists and increases. A hazard assessment including an identificationo f source areas and subsequent monitoring of glacial lakes is proposed. It should be incorporated into any development concept for the Himalayan region.

Effects of Waste Disposal Operations in Estuaries and the Coastal Ocean

Since about 1800, human activities have significantly altered shorelines, bottom topography, sediment characteristics, and marine life in estuarine and coastal waters. The first man-induced changes of thc ocean were restricted to nearshore waters and most were small, scattered, and primarily associated with food production or port development (Klimm 1956). Sediment deposition caused by erosion of agricultural lands resulted in extensive delta building and shoreline changes in the Persian Gulf, the Adriatic Sea, and the Mississippi Delta, to name a few examples (Davis 1956). Diking and draining of wetlands, shallow ocean areas, and lakes to form agricultural land has greatly altered shorelines in the Netherlands and England (Davis 1956). Not all wastes are placed directly in the ocean. Some are brought there by normal sediment transport processes. For example, mining is a prolific sediment producer and has also caused extensive changes in wetlands and shorelines due to downstream sediment deposition. Perhaps the best studied case is the hydraulic mining of gold in California's Sierra Nevada (Gilbert 1917). Between 1850 and 1914, 1.8 x 109 m3 of debris was mobilized by mining and erosion in the San Francisco Bay drainage system. About 1.1 x 109 m 3 was deposited in the bay system or on wetlands (Gilbert 1917). Movement and deposition of this material apparently persisted for approxi­ mately 50 years after cessation of mining (Smith 1965). More recently, rapid growth of coastal cities and associated industry has led to greatly incrcascd construction, demolition, and dredging, and the disposal of wastes produced from these activities has emerged as a geologic process causing significant changes in coastal areas. Because waste solids have caused the most obvious geologic changes, this review deals primarily with these materials. Effects of dissolved wastes such as nutrients have been extensively discussed elsewhere (NAS 1969, Likens 1972).

Glacier-caused slide near Pylon Peak, British Columbia

A glacier-initiated land–ice slide occurred on the southwestern side of Devastation Glacier near Pylon Peak in the Coast Mountain Range, British Columbia, in July 1975. An estimated 2.5 × 106 m3 of ice and about 26 × 106 m3 of debris descended 1150 m over a distance of 6.5 km and blocked Meager Creek, forming a small lake. The slide claimed the lives of four people on a sand bar at Meager Creek.

Two Case Studies of Mudflows in the Buzau Subcarpathians

Stationary investigations of the mudflows recorded in the Buzău Subcarparthians (southeast of the Carpathian chain) have revealed some peculiarities of both their involvement in slope modeling and their dynamics. The first mudflow investigated carried, in the course of eight years, 21,500 m3 of debris. These deposits gradually reached the mudflow track due to the successive release of some slides and falls in the source area. The second example (48,000 m3 displaced) refers to a mudflow triggered by extreme rainfalls (177.8 mm rain in 24 hours).

Two Case Studies of Mudflows in the Buzau Subcarpathians

Stationary investigations of the mudflows recorded in the Buzău Subcarparthians (southeast of the Carpathian chain) have revealed some peculiarities of both their involvement in slope modeling and their dynamics. The first mudflow investigated carried, in the course of eight years, 21,500 m3 of debris. These deposits gradually reached the mudflow track due to the successive release of some slides and falls in the source area. The second example (48,000 m3 displaced) refers to a mudflow triggered by extreme rainfalls (177.8 mm rain in 24 hours).