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Nella Larsen's Quicksand (1928) demonstrates a situated form of Black cosmofeminism to capture the difficult process through which a deviant mixed-race heroine negotiates her place in the Black community. At core, Black cosmofeminism interrogates oppressive racial and sexual politics enacted in domestic, local, and national spheres to envision a more inclusive cosmopolitan US Black community open to sexually, racially, and nationally "impure" subjects. However, far from advocating the erasure of local identities, such a reimagining of the domestic Black community as cosmofeminist instead foregrounds group identification and communal bonding developed in response to transnational displacement and discrimination. Working in tandem with consumer cosmopolitanism, Black cosmofeminism places the African American woman consumer center stage and traces how her desire, body, and identity are not only constructed alongside globally circulated commodities but also made localized and resistant to the global commodification and sexualization of Black and mixed-raced women. [ABSTRACT FROM AUTHOR]

In the article, the feature of settlement, subsidence, and other deformations in the ground foundations of various structures built in complex engineering-geological conditions with the joint participation of some soils with a stable structure (subsidence loess, silt, low-strength technogenic, soluble) are performed on the example of the Gazakh cement plant, the development of a conceptual solution for the methods of installation in foundations on such soils has been reflected. Analyzing the results of the complex engineer-geological research conducted at the research facility, priority was given to the principle of improving the working conditions of the soils that form the basis of the facilities in order to prevent the predicted large-scale deformation, the application of a foundation system consisting of piles with a large length, with the bottom placed in a layer of argillite-like very stiff clay, was accepted as the most correct technical solution, the dimensions of the pile are determined and installed in the study area and it was determined that the chosen solution was justified by monitoring the deformations. [ABSTRACT FROM AUTHOR]

Swallowing of large objects and humans by quicksand fascinated writers for long time. Previously, it was believed that sand must contain liquid to achieve such characteristics. However, recently it has been proposed that even undampened loose sand (like in deserts) can swallow large objects and investigated in this paper. In this study, numerical simulations are performed using computational fluid dynamics (CFD) and discrete element method (DEM). The transition from packed to quicksand like state in granular material is obtained by passing gas near to minimum fluidization velocity and keeping bed stationary. It is observed in simulations that dry quicksand acts more like a fluid and the granular drag force due to penetration of intruder becomes isotropic and depth independent which is a deviation from packed bed. At the end of paper, the physics behind this behavior is explained by comparing force chains formed in packed and dry quicksand. Resistance force on intruder (a) Packed bed (b) Quicksand (c) Force chains in packed bed (d) Force chains in quicksand. Image 1 • Granular drag force acting on intruder during immersion in quicksand is investigated and compared with packed bed. • Quicksand acts like fluid and the granular drag force becomes isotropic and independent with immersion depth. • Reason for this deviation is due to absence of force chains in quicksand which are strong for dry packed bed of particles. [ABSTRACT FROM AUTHOR]

Under the fragile geological environment conditions in Shanghai, intensively distributed underground pipelines and large-scale development of underground space have brought severe challenges to urban geological safety. This paper starts with the “shallow sand layer” distribution area, where surface collapse disasters occur frequently, systematically investigates the typical characteristics and influencing factors of the disaster, then researches the risk assessment of continual collapse disasters and monitoring of the early warning of hidden dangers. Firstly, the indicator system for risk assessment needs to be constructed. The relative index data are classified as two aspects of fatalness and vulnerability, including geological and hydrogeological engineering, underground pipelines and underground space, meteorological hydrology, basic geographic information, human engineering activities, and human risk resistance capabilities. This was carried out to form hierarchical zoning of the risk for land collapse disasters in Shanghai by using the ArcGIS program as a platform. Secondly, the prevention and control of urban land subsidence disasters is a multi-source and multi-dimensional endeavor. It is necessary to conduct in-depth investigations on the affecting factors and establish a basic data system, including geological conditions and underground facilities, etc. Further improving and refining risk zoning is a prerequisite for the effective prevention and control of urban ground collapse disasters; comprehensive application with geological radar, three-dimensional laser scanning, automatic monitoring, and other investigation methods are performed on this bases. Through multi-stage work such as census, detailed investigation, and monitoring, it is possible to investigate and monitor the abnormal hidden dangers of different objects, for instance, underground facilities, underground cavities, soil displacement, groundwater level, etc. Furthermore, it helps achieve the early warning of ground collapse disasters effectively. Relevant research results have great significance on urban refined management and safe operations, which will promote the prevention and control of ground subsidence disasters in Shanghai, gradually changing to a holistic, long-term, and systematic direction. [ABSTRACT FROM AUTHOR]

The article presents an essay that explores the nature of the concept of quicksand across a range of texts including the books "Living On: Borderlines" by philosopher Jacques Derrida and "The Beast and the Sovereign." Topics discussed include the book "Giving Birth" by Margaret Atwood that precedes Derrida's text.

This paper deals with the numerical simulation of the quicksand phenomenon using a coupled Discrete Elements - Lattice Boltzmann hydromechanical model. After the presentation of the developed numerical model, simulations of ascending fluid flow through granular deposits are performed. The simulations show that the quicksand actually triggers for a hydraulic gradient very close to the critical hydraulic gradient calculated from the global analysis of classical soil mechanics, that is, when the resultant of the applied external pressure balances submerged weight of the deposit. Moreover, they point out that the quicksand phenomenon does not occur only for hydraulic gradients above the critical hydraulic gradient, but also in some cases with slightly lower gradients. In such cases, a more permeable zone is first gradually built at the bottom of the deposit through a grain rearrangement, which increases the hydraulic gradient in the upper zones and triggers the phenomenon. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a numerical simulation of quicksand or sand flow hazard through the broken rock mass in the caving zone due to coal mining based on DEM.The panel 22402 of the Halagou Coalmine was taken as the study site in this paper. The fragment-size distribution of caving zone was analyzed by using the fractal theory and then a numerical model of quicksand through the broken rock mass of caving zone with random shape was constructed by using DEM according to the fragment-size distribution. The simulation results show that the caving zone with large voids or pores and good connectivity are the dominant pathways for sand migration；the voids and pores in the caving zone can store the aeolian sand. The poorly graded rock mass in caving zone has a certain effect to block the sand flow；the velocity profiles of sand flow are of spindle type which mean that the sand flow velocities along the centerline are larger than those near the wall. [ABSTRACT FROM AUTHOR]

Environmental change increasingly effects internal and external patterns of human movement around the globe. Whether due to loss of livelihood from rising sea waters, degradation of arable land, or increased frequency and severity of storms, people are on the move. This article looks at environmental factors driving this new wave of migrants and provides a set of 'guiding principles' for policymakers, international institutions, NGOs, academia, and the think tank community to create new policies, and the obstacles they may face in implementation. [ABSTRACT FROM AUTHOR]

The widespread use of social media and its potential to hinder academic performance has received the attention of researchers and is a growing concern of educators. This phenomenological study explored the perceived impact of social media on the educational experiences of university students in the United States, both in and out of the classroom. Analysis of semi-structured interviews revealed several pervasive themes, all of which can be viewed as barriers to academic success. Participants reported that using social media during academic activities diminishes achievement, increases the amount of time it takes to complete tasks, and reduces how much information students retain from study and lecture sessions. Additionally, participants indicated how a lack of situational and topic interest increases social media's temptation. We argue that educators and students would benefit from a more complete understanding of social media's role as a barrier to academic success. Implications for educators are discussed. [ABSTRACT FROM AUTHOR]

In coal mining, a poorly sealed borehole is one of the channels that can lead to an inrush of water and quicksand movement, seriously compromising the safety of the coal mine. In this paper, we used the water inrush and quicksand incident at Longde Coal Mine as an example in order to investigate the mechanism of water inrush and quicksand movement induced by a borehole, as well as to develop measures for the prevention and remediation of such problems. Two sand funnel models and a water inrush outlet model are introduced from which to calculate the flow of the water and quicksand; a comparison of the two shows that the flow predicted by the water inrush outlet model is more consistent with observations from the accident than the sand funnel models. Based on the water inrush outlet model, the aquifer thickness and borehole diameter are the two key factors affecting the flow. The aquifer channel is inferred as tubular, with its diameter gradually decreasing from ground surface to underground, and a time-dependent surface subsidence model is constructed. Finally, we develop a prevention method, 'Prior to mining development, borehole should be investigated and plugged for prevention,' and propose a remediation method, 'Changing the pipeline flow into fracture flow, followed by changing the fracture flow into pore flow, and finally grouting and plugging.' [ABSTRACT FROM AUTHOR]

This paper presented an investigation of closure effect of mining-induced fractures under thick sand aquifers 15 years after coal mining by using color borehole television, mud slurry leakage and RQD (Rock Quality Designation) of cores, for the purpose of understanding the time effect on mining-induced fracture development and providing a basis for the evaluation of abandoned coal seam remining. The results show that the joint openness and fracture porosity in the rockmass far away from the roof of the coal seam are relatively small and easily compressed. The fractures with larger opening in the rock mass near the roof of the coal seam cannot be compressed to close. The height of water flowing fractured zones reduced by nearly 40% after 15 years, while the height of caving zone just reduced slightly. The uniaxial compressive strengths of overburden after mining reduced by about 20% compared with those before mining; the uniaxial compressive strength of broken rock mass with potential plastic state was only 0. 237 MPa calculated with Hoek-Brown empirical rock failure criterion. Therefore, the formulae for soft rock failure should be used to calculate the overburden failure due to re-mining of the residual coal seam. The research also indicates that the height of safety pillars of more than 15.7 or 18.2 m is required to prevent panels with a re-mining cutting height of 2 or 3 m of seam No. 3 in the Yangzhuang Coal Mine, Shandong Province from quicksand. [ABSTRACT FROM AUTHOR]

In the civil engineering, the soils represent a relatively loose material originating from the upper rock layers or from the soil profile itself. There are many soil - forming processes. Soil - forming processes vary with time but also with parent materials, topographical relief, vegetation, and climate. Poor soil conditions in terms of engineering increase the cost of construction. Fundamental soil properties such as cation exchange and shrink - swell properties are all influenced by molecular - scale differences in soil clay minerals. The following outlines of soil - forming processes are presented: gleization (develop anaerobic conditions in the upper part), paludization (is an accumulation of undercayed plant debris), podzolization (are soils characterized by the presence of a spodic horizon), ferrolysis (a hardpan of iron oxide may build up at the interface of the aerobic and anaerobic zones), ferrallitization, biocycling, lessivage is the process of clay accumulation; Lixiviation is a process of leaching of major cations from soil minerals and their loss from the soil in groundwater; melanisation, andisolization, vertization - is the physical soil overturning and mixing, characteristic of soils rich in swelling clays (smectites), which swell when wet and shrink when dry; anthrosolization - said, about any modification of properties, due to human activity, including soil modifications that may significantly influence soil development; salinization, solonization, cryoturbation. Quicksands are encountered in excavations made in fine sands that are below the watertable. Loess is, from this point of view, a typical collapsible material. The structural stability of collapsible soils is related to the suffusion process, that is the process of lateral and vertical removal of the fine soil particles by subsurface flow, often leading to settling, formation of potholes or piping. Chemical and hydrodynamic suffosion are distinguished. These volume changes can give rise to ground movements that may result in damage to buildings, and also in road construction. Severe erosion or worse, serious piping damage to embankments and piping failures of earth dams have occurred when dispersive soils have been used in their construction. Excessive settlement are the principal problems confronting the engineer working on a peat soil. A number of technique can be used to stabilize these soils. [ABSTRACT FROM AUTHOR]

Although the use of hydrogen exchange (HX) mass spectrometry (MS) to study proteins and protein conformation is now over 20 years old, the perception lingers that it still has 'issues.' Is this method, in fact, still in the quicksand with many remaining obstacles to overcome? We do not think so. This critical insight addresses the 'issues' and explores several broad questions including, have the limitations of HX MS been surmounted and has HX MS achieved 'indispensable' status in the pantheon of protein structural analysis tools. [ABSTRACT FROM AUTHOR]

We report numerical results of effective attractive forces on the packing properties of two-dimensional elongated grains. In deposits of non-cohesive rods in 2D, the topology of the packing is mainly dominated by the formation of ordered structures of aligned rods. Elongated particles tend to align horizontally and the stress is mainly transmitted from top to bottom, revealing an asymmetric distribution of local stress. However, for deposits of cohesive particles, the preferred horizontal orientation disappears. Very elongated particles with strong attractive forces form extremely loose structures, characterized by an orientation distribution, which tends to a uniform behavior when increasing the Bond number. As a result of these changes, the pressure distribution in the deposits changes qualitatively. The isotropic part of the local stress is notably enhanced with respect to the deviatoric part, which is related to the gravity direction. Consequently, the lateral stress transmission is dominated by the enhanced disorder and leads to a faster pressure saturation with depth. [ABSTRACT FROM AUTHOR]

It is well known that a splash occurs when an object impacts at high velocity on a liquid's surface. If the impact is fast enough, surface tension and air pressure gradients pull the crown-shape splash all the way towards the axis of symmetry, making it to collapse and seal the surface. In this paper we show that splash and surface sealing are also observed in impacts on soft, dry sand. We observe influence of air pressure and grains size on the shape of the splash. By tracking individual grains using high-speed imaging we calculate their acceleration, which results from gravity and drag forces. Assuming friction drag parallel, and pressure drag perpendicular to the direction of motion of grains we estimate the friction and pressure drag contributions to the drag force. Our results support the idea that pressure drag from Bernoulli effect is at the origin of the surface seal. [ABSTRACT FROM AUTHOR]

Based on the engineering geological modes of quicksand inrush induced by coal mining under the thin bedrock and thick unconsolidated formations, a test model of the mixed water and sand flow transfer and inrush was designed. The variation characteristics of water pressure in different position of the fissure channel were revealed by considering the various compositions of the flow and variations of the width of the fractured channel under the water pressure of 0.05 MPa and 0. 10 MPa. Geological information of the mixed water and sand flow transfer for the various compositions of the flow, water pressure and the channel feature was quantitatively studied. The water pressure variation curves in the different positions were gained from different model tests. The relations between the channel width and the velocity of the mixed water and sand flow in the fractured channel were analyzed. The relationship between time and sand production volume of the mixed water and sand flow channel overflows was obtained from observational results. [ABSTRACT FROM AUTHOR]

The discrete element method constitutes a general class of modeling techniques to simulate the microscopic behavior (i.e. at the particle scale) of granular/soil materials. We present a contact dynamics method, accounting for the cohesive nature of fine powders and soils. A modification of the model adjusted to capture the essential physical processes underlying the dynamics of generation and collapse of loose systems is able to simulate 'quicksand' behavior of a collapsing soil material, in particular of a specific type, which we call 'living quicksand'. We investigate the penetration behavior of an object for varying density of the material. We also investigate the dynamics of the penetration process, by measuring the relation between the driving force and the resulting velocity of the intruder, leading to a 'power law' behavior with exponent 1/2, i.e. a quadratic velocity dependence of the drag force on the intruder. [ABSTRACT FROM AUTHOR]

The image of quicksand merciless swallowing a victim has inspired the fantasy of kids and helped writers and moviemakers to get rid of evil figures. Is this really possible? This is still disputed since till today it is not even clear what quicksand exactly is. In soil mechanics, the “quick-condition” is usually described as a liquefaction due to high water pressure essentially possible with any soil. However, previous studies have detected anomalous rheological properties from natural quicksand. Pushed by these contradicting points of view we set off to Lençois Maranhenses in North-East Brazil, where quicksands are common, to investigate rheology and strength in situ. We found that along very quiet drying lakes cyanobacteria cement an impermeable crust above a suspension of grains. Beyond a critical pressure, the crust fails releasing water from the collapsing colloidal structure and radically changing the depth dependence of the shear strength from a constant to a linear function. The sedimenting solid fraction and the rapid increase of shear strength can indeed trap an intruder endangering his life if the basin is sufficiently deep. As opposed to some previous studies, we find that this quicksand condition cannot be restored once it has collapsed. Finally, we also show some preliminary results from a contact dynamics model specially designed to mimic the living quicksand behavior. [ABSTRACT FROM AUTHOR]

We investigate a collection of one-parametric families of isotropic sandpile models. The models involve the square lattice slowly accumulating the grains and quickly transferring them as the local piles become over-critical. The paper groups the sand-piles with respect to two features influencing the model dynamics. They are the value of the local transfer's stochasticity and the number of the transferred grains. Every pair generates one-parametric family of the sand-piles. The parameter reflects the relative height of an over-critical pile with respect to the incoming flow of sand. If the stochasticity disappears with the growth of the parameter, the families with the fixed number of the transferred grains have much in common with Bak et al.'s sand-pile [Phys. Rev. Lett.59, 381 (1987)], while the families, whose over-critical piles lose all their grains, tend to the Zhang sand-pile [Phys. Rev. Lett.63, 470 (1989)]. The families with non-disappearing variance give rise to new properties described in terms of the probability distribution of the pile heights. [ABSTRACT FROM AUTHOR]

Abstract: A coupled continuum-discrete hydromechanical model was utilized to analyze the meso-scale pore fluid flow and micro-scale solid phase deformation of saturated granular soils. The fluid motion was idealized using averaged Navier–Stokes equations and the discrete element method was employed to model the solid particles. Well established semi-empirical relationships were used to quantify the fluid–particle interactions. Numerical simulations were conducted to investigate the mechanisms of granular deposit liquefaction in the presence of a critical upward pore fluid flow as well as when subjected to a dynamic base excitation. The outcome of these simulations was consistent with experimental observations and revealed valuable information on the micro-mechanical characteristics of soil liquefaction and associated loss of stiffness and strength. [Copyright &y& Elsevier]

Studies involving stabilization of saturated soils prior to opening the upper level of the connector between the Serebryanoborsk transportation and service tunnels in Moscow are described. [ABSTRACT FROM AUTHOR]

This study aimed to identify displacement properties of landslide masses at the initiation of failure and factors that affect the landslides activities in areas where quick clay is found. We set up a research site in a quick clay deposit area in Norway and monitored the displacements of landslide masses and meteorological and hydrological factors for a long period of time using an automatic monitoring system. The system collected data for two landslides that occurred at the site from the start of their movement until their ultimate collapse.The two landslides that were monitored showed definite secondary and tertiary creep stages before they collapsed. One of the landslides moved from the secondary stage to the tertiary creep stage when another landslide occurred nearby. The tertiary stage of this landslide showed reconstruction of short primary, secondary, and tertiary creep stages. These phenomena suggested that (1) the stress at the end of the landslide mass was released during the nearby landslide, and (2) a new stress distribution was formed in the landslide mass. The critical strain differed for 14 times between the two landslide masses we monitored. The difference was likely attributable to the difference in the contents of quick clay, which shows small critical stress against slope failure, as well as topological factors.Our analyses of the effects of hydrological and meteorological factors on landslides showed that the precipitation of 3 and 10 days before six slope failures as the final stages of the landslides that had occurred in the research area was no different from the mean precipitation of periods that showed no slope failure, suggesting that precipitation had no direct effects on the collapse of the landslide masses. On the other hand, the traveling velocities of the landslide masses during the secondary creep stage, which was prior to their collapse, were affected by the water content of the soil and precipitation (and the amount of snowmelt water), but was little correlated with the pore-water pressure of the quick clay layer. We also found that the presence of snow cover scarcely affected landslide movements. [Copyright &y& Elsevier]

Presents a strategy in teaching students about density and volume characteristics of quicksand. Activity programs; Materials used; Objectives.

We discuss the difference between cohesive and non-cohesive granular media in the context of dry quicksand, recently proposed as a new fragile state of sand. We demonstrate that weak low density configurations with properties like dry quicksand are readily formed in many common household powders. In contrast, such states cannot be formed in non-cohesive granular media such as ordinary sand. [ABSTRACT FROM AUTHOR]

Sand can normally support a weight by relying on internal force chains. Here we weaken this force-chain structure in very fine sand by allowing air to flow through it: we find that the sand can then no longer support weight, even when the air is turned off and the bed has settled-a ball sinks into the sand to a depth of about five diameters. The final depth of the ball scales linearly with its mass and, above a threshold mass, a jet is formed that shoots sand violently into the air. [ABSTRACT FROM AUTHOR]

The article provides information on the analysis on the study on liquefiable sands in sloping ground. The study primary purpose of the study is to examine and measure the yield and critical strength of liquefiable sands observed in sloping ground. The study cites the scatter values in measuring sand density. The study emphasizes the significance of post-liquefaction method in measuring the yield and critical strength of the sands. The study concludes the need of accurate and further methodology in assessing in situ of liquefiable sand deposits.

People or animals caught in quicksand find it very hard to escape. Here we show that quicksand acts as a trap because it becomes unstable when it is forced to move — first it liquefies, and then it collapses. But a simple sinking test demonstrates that it is impossible for a human to be drawn into quicksand altogether. [ABSTRACT FROM AUTHOR]

The article presents the author's experience of visiting Mont St. Michel, France in summers. The author says that there were warning signs about the quicksands in the bay, but their feet sank into the melted tar of the car park as it was so hot. Mont St. Michel and St. Malo had just been rocks in a salt marsh before the tidal wave of 790 had swept out all the bay.