Interactions of landslide deposit with terrace sediments: Perspectives from velocity of deposit movement and apparent friction angle
TL;DR: In this article, a total of 40 loess landslides in the South Jingyang Platform, Shaanxi Province, were investigated in detail, with an emphasis on the geomorphology feature and the internal geometry of geology.
About: This article is published in Engineering Geology.The article was published on 2021-01-01. It has received 41 citations till now. The article focuses on the topics: Landslide & Loess.
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TL;DR: In this article, the micro-scale 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.
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.
74 citations
TL;DR: Wang et al. as discussed by the authors explored the potential use of the EICP technology for the protection of heritage buildings in NW China and found that the modified version performed the best with the highest calcite precipitation.
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.
48 citations
TL;DR: In this paper , the micro-structural characteristics of the loess specimens that are exposed to acetic acid or sodium sulfate, are studied using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy analyses.
Abstract: When exposed to chemicals, the micro-structural evolution of the loess and the impacts on the macro-mechanical properties are considered crucial for contaminated land reclamation. In this study, the micro-structural characteristics of the loess specimens that are exposed to acetic acid or sodium sulfate, are studied using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy analyses. Further, their macro-mechanical properties are determined by direct shear tests. The corrosion of the cement between particles under acetic acid environments and the salt-induced swelling under saline conditions play an important role in the micro-structural deterioration. The cohesion and friction angle for the wetted loess are about 16 kPa and 19° respectively, while for the acetic acid-contamianted loess, they reduce to 10 kPa and 15° respectively. They, for the sodium sulfate-contaminated loess, reduce further to below 10 kPa and 13° respectively. The macro-mechanical properties show good correspondence with the micro-structural deterioration.
38 citations
TL;DR: 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, and the potential for one-class support vector machines (OCSVM), isolation forest and robust covariance (Robcov) to assess the tendency for clogging is explored.
34 citations
References
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TL;DR: In this paper, runout analyses are used for risk assessment and design of remedial measures against rapid landslides such as debris flows, debris avalanches, rockslide avalanches and large-scale liquefaction failure.
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...
980 citations
TL;DR: In this paper, the authors 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.
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.
243 citations
TL;DR: Wang et al. as discussed by the authors studied the formation and moving characteristics of the landslide and subsequent debris flow in the southern Dagou Village of Mapaoquan Town, Tianshui City, Gansu Province of China on July 21, 2013.
163 citations
TL;DR: In this paper, a finite element code is used to simulate the motion of a moving landslide mass on materials with different properties and along very sharp topographies, where erosion and deposition can be modelled as well as interaction with obstacles of different characteristics.
162 citations
TL;DR: Wang et al. as discussed by the authors showed that the water saturation degree in the landslide depression was relatively high and the leading edge was in a flow state; there were some local natural sub-areas, but the overall area showed a characteristic fluidized.
138 citations