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Journal ArticleDOI: 10.1007/S10064-021-02144-2

Sandbox modelling of interactions of landslide deposits with terrace sediments aided by field observation

02 Mar 2021-Bulletin of Engineering Geology and the Environment (Springer Berlin Heidelberg)-Vol. 80, Iss: 5, pp 3711-3731
Abstract: The Loess Plateau can be considered as a landslide-prone area in northwest China. The genera consensus about the interaction between landslide deposit and terrace sediments is not well studied; this paper summarised 40 loess landslides in the South Jingyang Platform, Shaanxi Province, China to help understand of this issue. Four of the loess landslides with high mobility have been analysed in detail. Three trenches T1, T2 and T3 dug after the loess landslides LD37, LD11 and LD38 highlighted the landslide-induced changes in geomorphology and internal geometry of geology, respectively. Furthermore, observation of upwards seepage flow on the profile of trench T3 is believed to be the trigger of the high speed, and long runout flowslides in the study area. A newly developed sandbox apparatus is used to reproduce the landslide kinematics due to a mass travelling over an inclined plane. The sandbox experiments show that the sediments are sheared and pushed upwards after the collision with the deposits. The deposits are then wrapped in a space between sediments, which tends to form the ‘sandwich’ structure. The distal sediments are thrust when the loess deposits’ kinetic energy consistently dissipates, developing the accumulated folded strata. These results reveal the deposits’ interactions with the sediments in the study area and provide key guideposts regarding prevention and mitigation of loess landslide hazards.

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Topics: Landslide (57.99%), Loess (56%)

5 results found

Journal ArticleDOI: 10.1016/J.TUST.2021.103908
Abstract: ‘Clogging’ is a common issue encountered during tunnelling in clayey soils which can impede tunnel excavation, cause unplanned downtimes and lead to significant additional project costs. Clogging can result in a drastic reduction in performance due to reduced jacking speeds and the time needed for cleaning if it cannot be fully mitigated. The data acquired by modern tunnel boring machines (TBMs) have grown significantly in recent years presenting a substantial opportunity for the application of data-driven artificial intelligence (AI) techniques. In this study, a baseline assessment of clogging in slurry-supported pipejacking is performed using a combination of TBM parameters and semi-empirical diagrams proposed in the literature. The potential for one-class support vector machines (OCSVM), isolation forest (IForest) and robust covariance (Robcov) to assess the tendency for clogging is then explored in this work. The proposed approach is applied to a pipejacking case history in Taipei, Taiwan, involving tunnelling in soft alluvial deposits. The results highlight an exciting potential for the use of AI techniques to detect clogging during slurry-supported pipejacking.

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Topics: Clogging (51%)

9 Citations

Journal ArticleDOI: 10.1016/J.CATENA.2021.105361
01 Aug 2021-Catena
Abstract: Soil contamination not only can cause environmental problems but also lead to a notable change in the mechanical properties of soil. Loess widely distributed over North-West (NW) China is featured with the metastable structure, and chemical contaminants produced especially during the rapid development of NW China in recent years seriously threaten the fragile loess environments. When exposed to chemical contaminants, the impacts on the microstructural characteristics of the loess and the resultant mechanical properties are deemed critical for land reclamation in NW China. In light of this, the microscale structural characteristics of the loess exposed to acetic acid, phosphoric acid, sodium hydroxide, and sodium sulfate respectively are studied using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy tests. Additionally, their resultant macroscale mechanical properties are determined by direct shear tests. The deterioration mechanism regarding the microscale structural characteristics when exposed to the contaminants is revealed, and the resultant macroscale mechanical properties present a good correspondence with the deteriorated microscale structural characteristics. The findings of this work provide some guideposts for contaminated land reclamation in NW China.

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8 Citations

Open accessJournal ArticleDOI: 10.1038/S41598-021-99318-5
Zhong-Fei Xue1, Wen-Chieh Cheng1, Lin Wang1Institutions (1)
07 Oct 2021-Scientific Reports
Abstract: In addition to the shearing behavior of soil, the creep character is also considered crucial in determining the long-term shear strength. This especially holds true for the loess that possesses the metastable microstructure and is prone to landslide hazards. This study explored the potential application of straw reinforcement to enhance the shearing and creep properties of the Quaternary loess. The mechanism responsible for the straw reinforcement to elevate the peak shear strength was revealed. Furthermore, three creep characters, namely attenuating creep, non-attenuating creep, and viscous flow were identified in this study. The unreinforced and reinforced specimen behaved in a different manner under identical shear stress ratio condition. The reinforced specimen was superior in limiting the particle relative movement within the shear plane than the unreinforced specimen. The chain reaction of interparticle contact loss, accompanied with excessive viscous displacement, rapid weakening of creep resistance, and eventually accelerated creep displacement, provided an evidence for the formation mechanism of slow-moving landslide. The long-term shear strength using the isochronal stress–strain relationship may be used for optimising the design of high-fill embankment works.

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Topics: Creep (61%), Shear strength (57.99%), Shearing (physics) (56.99%) ... show more

3 Citations

Journal ArticleDOI: 10.1016/J.ENGFAILANAL.2021.105695
Weizhen Jiang1, Yong Tan1Institutions (1)
Abstract: Over the last 30 years, intense rainfall events due to abnormal climate change have brought about numerous excavation failures in the urban areas of China. These heavy rainfall-related engineering failures, characterized by failure or collapse of retaining structures and/or retained slopes, have caused large-scale damages to urban environment as well as injuries and casualties. Thus, a summary of such failures along with corresponding statistical patterns and contributing factors is essential, which can help practitioners further understand the risk of excavation failures associated with heavy rainfall and then could develop or adopt appropriate measures for prevention of future failures. Based on these considerations, this paper reviewed 170 excavation failure cases occurring during 1994–2018 in China, using a method of descriptive statistics. The review mainly focused on their statistical failure patterns (temporal distributions of failures, types of failures and types of failed soil strata, etc.) and contributory factors (e.g., heavy rainfall influences and technical factors). It was disclosed that the failures occurred in those deep excavations in sandy soils during summer more frequently. In general, the failures can be categorized into six basic types, which are mainly governed by 11 kinds of adverse influences of heavy rainfall (e.g., seepage erosion under high hydraulic gradient, intense runoff scouring and water gushing impact from broken storm sewers nearby, etc.) and 16 technical factors (e.g., ignorance or improper protection of adjacent preexisting drainage structures, deficiencies in drainage or dewatering system, and poor construction quality of temporary retaining structures, etc.). The findings and lessons learned from this review are practically useful for designers and contractors to reduce the incidence of future excavation failures in the context of global climate change.

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3 Citations

Open accessJournal ArticleDOI: 10.3389/FBIOE.2021.750258
Abstract: Given that acid-rich rainfall can cause serious damage to heritage buildings in NW China and subsequently accelerate their aging problem, countermeasure to protect their integrity and also to preserve the continuity of Chinese culture is in pressing need. Enzyme-induced calcite precipitation (EICP) that modifies mechanical properties of the soil through enhancing the inter-particle bonds by the precipitated crystals and the formation of other carbonate minerals is under a spotlight in recent years. EICP is considered as an alternative to the microbial-induced calcite precipitation (MICP) because cultivating soil microbes are considered to be challenging in field applications. This study conducts a series of test tube experiments to reproduce the ordinary EICP process, and the produced calcite precipitation is compared to that of the modified EICP process subjected to the effect of higher MgCl2, NH4Cl, and CaCl2 concentrations respectively. The modified EICP subjected to the effect of higher MgCl2 concentrations performs the best, with the highest calcite precipitation. The enhancement mechanism of calcite precipitation is well interpreted through elevating the activity of urease enzyme by introducing the magnesium ions. Further, the degradation of calcite precipitation presents when subjected to the effect of higher NH4Cl concentration. The decreasing activity of urease enzyme and the reverse EICP process play a leading role in degrading the calcite precipitation. Moreover, when subjected to the effect of higher CaCl2 concentrations, the slower rate of ureolytic hydrolysis and the decreasing activity of urease enzyme are primarily responsible for forming the ‘hijacking’ phenomenon of calcite precipitation. The findings of this study explore the potential use of the EICP technology for the protection of heritage buildings in NW China.

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Topics: Calcite (51%), Magnesium ion (51%)


54 results found

Journal ArticleDOI: 10.1139/T95-063
Abstract: Runout analyses are used for risk assessment and design of remedial measures against rapid landslides such as debris flows, debris avalanches, rockslide avalanches, large-scale liquefaction failure...

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Topics: Rockslide (68%), Landslide (57.99%), Debris (55%)

883 Citations

Journal ArticleDOI: 10.1016/S0013-7952(01)00090-4
Abstract: Several issues relevant to the mobility of long-runout landslides are examined. A central idea developed in this paper is that the apparent coefficient of friction (ratio of the fall height to the runout distance) commonly used to describe landslide mobility is physically meaningless. It is proposed that the runout distance depends primarily on the volume and not on the fall height, which just adds scatter to the correlation. The negative correlation observed between the apparent coefficient of friction and the volume is just due to the fact that, on the gentle slopes on which landslides travel and come to rest, a large increase in runout distance due to a large volume corresponds to a small increase in the total fall height, hence to a decrease in the apparent coefficient of friction. It is shown that the spreading of a fluid-absent, granular flow is not able to explain the large runout distances of landslides, and in particular does not allow the centre of mass to travel further than expected for a sliding block. This contrasts with the behaviour of natural landslides, for which the centre of mass is shown to travel much further than expected from a simple Coulomb model. The presence of an interstitial fluid which can partly or entirely support the load of particles allows the effective coefficient of solid friction to be reduced or even suppressed. Air is not efficient for fluidising large landslides and a loose debris cannot slide over a basal layer of entrapped and compressed air, as air would rapidly pass through the debris in the form of bubbles during batch sedimentation. Water is much more efficient as a fluidising medium due to its higher density and viscosity, and its incompressibility. As water is known to enhance the mobility of the saturated debris flows, it is proposed that water is also responsible for the long runout of landslides. This is consistent with the fact that the increase in runout with volume is similar for debris flows and landslides. Field evidence suggests that most landslides are unsaturated with water but not dry, even on Mars. Comparison of the velocity of well-documented landslides with that predicted by fluid-absent, granular models shows that these models predict landslides that are much faster and less responsive to topography than natural ones. The relatively low velocities of landslides suggest that energy dissipation is dominated by a velocity-dependent stress and that the coefficient of solid friction is very low. This is consistent with the physics of fluidised or partly fluidised debris and suggests that landslide velocity may be controlled by local slope and flow thickness rather than by the initial fall height. In the absence of a supply of fluid at the base, fluidisation requires a net downward flux of sediment, implying some deposition at the base of landslides, which may thus progressively run out of material. In such a model, the spreading of the portion of a landslide beyond a certain distance would primarily depend on the volume passing this distance and not on the total volume of the landslide. Landslide deposits may therefore have self-similar shapes, in which the area covered beyond a certain distance is a constant function of the volume beyond that distance. It is shown that the shape of some well-documented landslide deposits is in reasonable agreement with this prediction. One consequence is that, as recently proposed for debris flows, assessment of hazards related to landslides should be based on the correlation between the volume and the area covered by the deposit, rather than on the apparent coefficient of friction.

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Topics: Landslide (60%), Debris flow (59%), Debris (51%)

604 Citations

Journal ArticleDOI: 10.1130/B25362.1
Oldrich Hungr1, Stephen G. Evans2Institutions (2)
Abstract: Many rock avalanches entrain and liquefy saturated soil from their paths. Evidence for this includes mud displaced from the margins of rock avalanche deposits, substrate material smeared along the base of deposits, extrusion of liquefied soil upward through the deposits, and increases of volume. A hypothesis first suggested in 1881 and since reinforced by several authors suggests that entrainment of substrate material increases mobility. Although the process has been discussed in the literature for more than 100 years, few detailed and quantitative descriptions exist. The main purpose of this paper is to describe two recent cases from British Columbia, Canada, where rockslides entrained substrate on a very large scale, influencing the character of the events. Estimated volume balance curves, based on detailed field mapping, are provided for both cases. Dynamic analyses are carried out using a numerical model and using the same set of rheological parameters. The mechanism of material entrainment and displacement is discussed. The data suggest that rapid rock failures entraining very large quantities of saturated substrate material represent a special type of landslide, transitional between rock avalanche and debris avalanche. Many rock avalanches can thus be seen as end members of a continuum of phenomena involving rock failure followed by interaction with saturated substrate.

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Topics: Rockslide (61%), Landslide (52%), Debris (51%)

378 Citations

Journal ArticleDOI: 10.1007/S10346-003-0004-Y
27 Feb 2004-Landslides
Abstract: Landslides are gravitational mass movements of rock, debris or earth. Some move very slowly, thus conforming to the field of statics, but some move rapidly. Study of the initiation and motion of rapid landslides needs to develop “Landslide Dynamics” involving dynamic loading and dynamic generation/dissipation of excess pore-water pressure. New developments in science can be facilitated by new technological advances. This study aimed to develop a new apparatus that can geotechnically simulate the formation of the shear zone and the following long and rapid shear displacement that occurs in high-velocity landslides. Professor K. Sassa and his colleagues at DPRI (Disaster Prevention Research Institute), Kyoto University, have worked to develop an undrained dynamic-loading ring-shear apparatus for this purpose. A series of different types of apparatus (DPRI-3, 4, 5, 6, 7) have been developed from 1992 to the present. This paper describes the development of this apparatus and its application to the study of earthquake-induced landslides and the latest landslide-triggered debris flow in Japan. Also, tests of the latest version (DPRI-7) with a transparent shear box for direct observation of the shear zone during a rapid shearing are described.

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Topics: Landslide classification (57.99%), Landslide (56%), Debris flow (52%) ... show more

239 Citations

Open accessJournal ArticleDOI: 10.1029/2009JF001462
Anne Mangeney1, Olivier Roche2, Oldrich Hungr3, N. Mangold4  +2 moreInstitutions (4)
Abstract: [1] We describe laboratory experiments of granular material flowing over an inclined plane covered by an erodible bed, designed to mimic erosion processes of natural flows travelling over deposits built up by earlier events. Two controlling parameters are the inclination of the plane and the thickness of the erodible layer. We show that erosion processes can increase the flow mobility (i.e., runout) over slopes with inclination close to the repose angle of the grains θr by up to 40%, even for very thin erodible beds. Erosion efficiency is shown to strongly depend on the slope of the topography. Entrainment begins to affect the flow at inclination angles exceeding a critical angle θc ≃ θr/2. Runout distance increases almost linearly as a function of the thickness of the erodible bed, suggesting that erosion is mainly supply-dependent. Two regimes are observed during granular collapse: a first spreading phase with high velocity followed by a slow thin flow, provided either the slope or the thickness of the erodible bed is high enough. Surprisingly, erosion affects the flow mostly during the deceleration phase and the slow regime. The avalanche excavates the erodible layer immediately at the flow front. Waves are observed behind the front that help to remove grains from the erodible bed. Steep frontal surges are seen at high inclination angles over both rigid or erodible bed. Finally, simple scaling laws are proposed making it possible to obtain a first estimate of the deposit and emplacement time of a granular collapse over a rigid or erodible inclined bed.

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Topics: Angle of repose (50%)

209 Citations

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