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基质吸力 2

非饱和土 2

Au/Ti双功能催化剂 1

H2有效利用率 1

三维 1

丙烯环氧化 1

主成分综合模型 1

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压板抗滑动试验 1

压板抗滑试验 1

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Determination of effective stress parameter of unsaturated soils: A Gaussian process regression approach

Pijush Samui, Jagan J

《结构与土木工程前沿(英文)》 2013年 第7卷 第2期   页码 133-136 doi: 10.1007/s11709-013-0202-1

摘要: This article examines the capability of Gaussian process regression (GPR) for prediction of effective stress parameter ( ) of unsaturated soil. GPR method proceeds by parameterising a covariance function, and then infers the parameters given the data set. Input variables of GPR are net confining pressure ( ), saturated volumetric water content ( ), residual water content ( ), bubbling pressure ( ), suction ( ) and fitting parameter ( ). A comparative study has been carried out between the developed GPR and Artificial Neural Network (ANN) models. A sensitivity analysis has been done to determine the effect of each input parameter on . The developed GPR gives the variance of predicted . The results show that the developed GPR is reliable model for prediction of of unsaturated soil.

关键词: unsaturated soil     effective stress parameter     Gaussian process regression (GPR)     artificial neural network (ANN)     variance    

Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

Nabarun DEY, Aniruddha SENGUPTA

《结构与土木工程前沿(英文)》 2020年 第14卷 第6期   页码 1462-1475 doi: 10.1007/s11709-020-0674-8

摘要: Slope failure occurs due to an increase in the saturation level and a subsequent decrease in matric suction in unsaturated soil. This paper presents the results of a series of centrifuge experiments and numerical analyses on a 55° inclined unsaturated sandy slope with less permeable, stronger silty sand layer inclusion within it. It is observed that a less permeable, stronger silty sand layer in an otherwise homogeneous sandy soil slope hinders the infiltration of water. The water content of the slope just above the stronger layer increases significantly, compared to elsewhere. No shear band is found to initiate in a homogeneous sandy soil slope, whereas for a non-homogeneous slope, they initiate just above the less pervious, stronger layer. A discontinuity of the shear zone is also observed for the case of a non-homogeneous soil slope. The factor of safety of a non-homogeneous, unsaturated soil slope decreases because of the less permeable, stronger layer. It decreases significantly if this less permeable, stronger soil layer is located near the toe of the slope.

关键词: non-homogeneous slope     stronger soil layer     factor of safety     centrifuge model test     unsaturated soils    

非饱和土的塑性体应变与剪应变的相互作用原理

王靖涛

《中国工程科学》 2007年 第9卷 第11期   页码 11-15

摘要:

将岩土塑性体应变与剪应变的相互作用原理拓展到了非饱和土领域。除了塑性体应变与剪应变的相互作用外,在非饱和土中出现了两类新的相互作用,吸力-塑性体应变和孔隙气压力-塑性体应变。吸力具有二重性质,其对塑性体应变作用包括两个相反的方面。基于吸力性质,阐明了非饱和土的一些独特的性质,诸如有效应力参数的物理涵义,吸力对体积变化和前期固结压力的影响和湿陷机理等。另外,应用拓展的塑性体应变与剪应变相互作用原理,从理论上证明了非饱和土的临界状态线是存在的和唯一的,以及它与应力历史无关。

关键词: 塑性体应变与剪应变的相互作用原理     非饱和土     基质吸力     有效应力原理    

Behavior of materials for earth and rockfill dams: Perspective from unsaturated soil mechanics

Eduardo E. ALONSO, Rafaela CARDOSO,

《结构与土木工程前沿(英文)》 2010年 第4卷 第1期   页码 1-39 doi: 10.1007/s11709-010-0013-6

摘要: The basis of the design of earth and rockfill dams is focused on ensuring the stability of the structure under a set of conditions expected to occur during its life. Combined mechanical and hydraulic conditions must be considered since pore pressures develop during construction, after impoundment and in drawdown. Other instability phenomena caused by transient flow and internal erosion must be considered. The prediction of the hydro-mechanical behavior of traditional and non-traditional materials used in the construction of dams is therefore fundamental. The materials used for dam’s construction cover a wide range from clayey materials to rockfill. In a broad sense they are compacted materials and therefore unsaturated materials. A summary of the current level of knowledge on the behavior of traditional materials used in the construction of dams is presented in the paper. Regular compacted materials (with a significant clay fraction), rockfill and compacted soft rocks are studied with more detail. The latter are non-traditional materials. They are analysed because their use, as well as the use of mixtures of soil and rock, is becoming more necessary for sustainability reasons.

关键词: dams     unsaturated soil mechanics     suction     rockfill     clayey soil     mixture    

Application of fractal theory to unsaturated soil mechanics

XU Yongfu, TONG Lixin

《结构与土木工程前沿(英文)》 2007年 第1卷 第4期   页码 411-421 doi: 10.1007/s11709-007-0056-5

摘要: The mechanical properties of unsaturated soils are a function of the saturation degree or matric suction, and can be obtained based on currently available procedures. However, each procedure has its limitations and consequently, care should be taken in the selection of a proper procedure. The fractal approach seems to be a potentially useful tool to describe hierarchical systems and is suitable to model the structure and hydraulic properties of unsaturated soils. In this paper, the soil-water characteristics, unsaturated hydraulic conductivity function, unsaturated shear strength, swelling deformation and compression were derived from the fractal model for the pore-size distribution, and were expressed by only two independent physical parameters, the fractal dimension and the air entry value. The predictions of the proposed soil-water characteristics, unsaturated hydraulic conductivity, unsaturated shear strength, swelling deformation and compression were in good agreement with published experimental data. Comparisons between the experimental results of unsaturated hydraulic conductivity and the predictions of the both fractal model and the van Genuchten-Mualem model were also performed, and it was found that the predictions of the fractal model were better than that of the van Genuchten-Mualem model.

关键词: selection     soil-water     independent physical     unsaturated     strength    

Soil-water interaction in unsaturated expansive soil slopes

ZHAN Liangtong

《结构与土木工程前沿(英文)》 2007年 第1卷 第2期   页码 198-204 doi: 10.1007/s11709-007-0023-1

摘要: The intensive soil-water interaction in unsaturated expansive soil is one of the major reasons for slope failures. In this paper, the soil-water interaction is investigated with the full-scale field inspection of rainwater infiltration and comprehensive experiments, including wetting-induced softening tests, swelling, and shrinkage tests. It is demonstrated that the soil-water interaction induced by seasonal wetting-drying cycles is very complex, and it involves coupled effects among the changes in water content, suction, stress, deformation and shear strength. In addition, the abundant cracks in the expansive soil play an important role in the soil-water interaction. The cracks disintegrate the soil mass, and more importantly, provide easy pathways for rainfall infiltration. Infiltration of rainwater not only results in wetting-induced softening of the shallow unsaturated soil layers, but also leads to the increase of horizontal stress. The increase of horizontal stress may lead to a local passive failure. The seasonal wetting-drying cycles tend to result in a down-slope creeping of the shallow soil layer, which leads to progressive slope failure.

关键词: strength     intensive soil-water     comprehensive     Infiltration     wetting-induced softening    

Stability analysis of layered slopes in unsaturated soils

Guangyu DAI; Fei ZHANG; Yuke WANG

《结构与土木工程前沿(英文)》 2022年 第16卷 第3期   页码 378-387 doi: 10.1007/s11709-022-0808-2

摘要: This study presents stability analyses of layered soil slopes in unsaturated conditions and uses a limit equilibrium method to determine the factor of safety involving suction stress of unsaturated soil. One-dimensional steady infiltration and evaporation conditions are considered in the stability analyses. An example of a two-layered slope in clay and silt is selected to verify the used method by comparing with the results of other methods. Parametric analyses are conducted to explore the influences of the matric suction on the stability of layered soil slopes. The obtained results show that larger suction stress provided in unsaturated clay dominates the stability of the layered slopes. Therefore, the location and thickness of the clay layer have significant influences on slope stability. As the water level decreases, the factor of safety reduces and then increases gradually in most cases. Infiltration/evaporation can obviously affect the stability of unsaturated layered slopes, but their influences depend on the soil property and thickness of the lower soil layer.

关键词: slope stability     suction stress     unsaturated soil     layered slope     limit equilibrium    

Assessment of future climate change impacts on water-heat-salt migration in unsaturated frozen soil using

Hanli Wan, Jianmin Bian, Han Zhang, Yihan Li

《环境科学与工程前沿(英文)》 2021年 第15卷 第1期 doi: 10.1007/s11783-020-1302-5

摘要: Abstract • A model coupling water-heat-salt of unsaturated frozen soil was established. • Future temperature, precipitation, and evaporation increase in freeze–thaw period. • Soil water, heat, and salt transport are closely coupled during freeze–thaw period. • Freeze–thaw cycles and future climate change can exacerbate salinization. The transport mechanisms of water, heat, and salt in unsaturated frozen soil, as well as its response to future climate change are in urgent need of study. In this study, western Jilin Province in north-eastern China was studied to produce a model of coupled water-heat-salt in unsaturated frozen soil using CoupModel. The water, heat, and salt dynamics of unsaturated frozen soil under three representative concentration pathway (RCP) scenarios were simulated to analyze the effects of future climate change on unsaturated frozen soil. The results show that water, heat, and salt migration are tightly coupled, and the soil salt concentration in the surface layer (10 cm) exhibits explosive growth after freezing and thawing. The future (2020–2099) meteorological factors in the study area were predicted using the Statistical Downscaling Model (SDSM). For RCP2.6, RCP4.5, and RCP8.5 scenarios, future temperatures during the freeze–thaw period increased by 2.68°C, 3.18°C, and 4.28°C, respectively; precipitation increased by 30.28 mm, 28.41 mm, and 32.17 mm, respectively; and evaporation increased by 93.57 mm, 106.95 mm, and 130.57 mm, respectively. Climate change will shorten the freeze–thaw period, advance the soil melting time from April to March, and enhance water and salt transport. Compared to the baseline period (1961–2005), future soil salt concentrations at 10 cm increased by 1547.54 mg/L, 1762.86 mg/L, and 1713.66 mg/L under RCP2.6, RCP4.5, and RCP8.5, respectively. The explosive salt accumulation is more obvious. Effective measures should be taken to prevent the salinization of unsaturated frozen soils and address climate change.

关键词: Soil salinization     Climate change     Unsaturated frozen soil     Water-heat-salt balance     Soil environment change    

Stable expression and control parameters in the numerical simulation of unsaturated flow

Zhiyuan ZHANG; Xu LI; Yongkang WU; Xiaokang LI

《结构与土木工程前沿(英文)》 2022年 第16卷 第12期   页码 1501-1514 doi: 10.1007/s11709-022-0893-2

摘要: The Richards’ equation describes the flow phenomenon in unsaturated porous media and is essential to hydrology and environmental science. This study evaluated the numerical stability of two different forms of the Richards’ equation. Sensitivity analyses were performed to investigate the control parameters of the equation. The results show that the h-form Richards’ equation has better applicability for calculating variable saturation flows than the θ-form Richards’ equation. For the h-form Richards’ equation, the hydraulic conductivity of the soil in the low-suction range and the specific moisture capacity in the high-suction range primarily influenced the solution. In addition, sensitivity analyses indicated that the saturated hydraulic conductivity, initial condition, and air-entry pressure have a higher sensitivity to the simulation results than the saturated water content, rainfall intensity, and decline rate of hydraulic conductivity. Moreover, their correctness needs to be guaranteed first in numerical simulations. The research findings can provide a helpful reference for improving the reliability of numerical simulations of unsaturated flows.

关键词: Richards’ equation     sensitivity analysis     unsaturated soil     hydraulic diffusivity     seepage simulation    

Assessment of pollution of potentially harmful elements in soils surrounding a municipal solid waste

Ying Han, Huiting Xie, Wenbin Liu, Haifeng Li, Mengjing Wang, Xuebin Chen, Xiao Liao, Nan Yan

《环境科学与工程前沿(英文)》 2016年 第10卷 第6期 doi: 10.1007/s11783-016-0873-7

摘要: Potentially harmful elements in ambient soil of a MSWI were assessed. Spatial distribution of potential ecological risk index was investigated. Health risk assessment of potentially harmful elements in soil was evaluated. Hg in the soil posed health hazards to the local population. We assessed the contamination levels of Mn, Zn, Cr, Cu, Ni, Pb, As and Hg and the risks posed by these potentially harmful elements in top-soils around a municipal solid waste incinerator (MSWI). We collected 20 soil samples, with an average pH of 8.1, and another fly ash sample emitted from the MSWI to investigate the concentrations of these elements in soils. We determined the concentrations of these elements by inductively coupled plasma–optical emission spectrometer (ICP-OES), except for Hg, which we measured by AF-610B atomic fluorescence spectrometer ( ). We assessed the risks of these elements through the use of geoaccumulation index ( ), potential ecological risk index ( ), hazard quotient ( ) and cancer risk ( ). The results showed that concentrations of potentially harmful elements in soil were influenced by the wind direction, and the concentrations of most elements were higher in the area northwest of the MSWI, compared with the area southeast of the incinerator, with the exception of As; these results were in accordance with those results acquired from our contour maps. According to the values, some soil samples were clearly polluted by Hg emissions. However, the health risk assessment indicated that the concentrations of Hg and other elements in soil did not pose non-carcinogenic risks to the local populations. This was also the case for the carcinogenic risks posed by As, Cr, and Ni. The carcinogenic risk posed by As was higher, in the range 6.49 × 10 –9.58 × 10 , but this was still considered to be an acceptable level of risk.

关键词: Soil     Potentially harmful elements     Contamination     Kriging interpolation     Risk assessment     Wind direction    

Carbon-doped surface unsaturated sulfur enriched CoS@rGO aerogel pseudocapacitive anode and biomass-derived

《化学科学与工程前沿(英文)》 2021年 第15卷 第6期   页码 1500-1513 doi: 10.1007/s11705-021-2086-2

摘要: As a hybrid energy storage device of lithium-ion batteries and supercapacitors, lithium-ion capacitors have the potential to meet the demanding needs of energy storage equipment with both high power and energy density. In this work, to solve the obstacle to the application of lithium-ion capacitors, that is, the balancing problem of the electrodes kinetic and capacity, two electrodes are designed and adequately matched. For the anode, we introduced in situ carbon-doped and surface-enriched unsaturated sulfur into the graphene conductive network to prepare transition metal sulfides, which enhances the performance with a faster lithium-ion diffusion and dominant pseudocapacitive energy storage. Therefore, the lithium-ion capacitors anode material delivers a remarkable capacity of 810 mAh∙g–1 after 500 cycles at 1 A∙g–1. On the other hand, the biomass-derived porous carbon as the cathode also displays a superior capacity of 114.2 mAh∙g–1 at 0.1 A∙g–1. Benefitting from the appropriate balance of kinetic and capacity between two electrodes, the lithium-ion capacitors exhibits superior electrochemical performance. The assembled lithium-ion capacitors demonstrate a high energy density of 132.9 Wh∙kg–1 at the power density of 265 W∙kg–1, and 50.0 Wh∙kg–1 even at 26.5 kW∙kg–1. After 10000 cycles at 1 A∙g–1, lithium-ion capacitors still demonstrate the high energy density retention of 81.5%.

关键词: in-situ carbon-doped     surface unsaturated sulfur enriched     pseudocapacitive energy storage     biomass-derived carbon     lithium-ion capacitors    

Healthy soils for sustainable food production and environmental quality

Xia LIANG, Jizheng HE, Fusuo ZHANG, Qirong SHEN, Jinshui WU, Iain M. YOUNG, Anthony G. O´DONNELL, Ligang WANG, Enli WANG, Julian HILL, Deli CHEN

《农业科学与工程前沿(英文)》 2020年 第7卷 第3期   页码 347-355 doi: 10.15302/J-FASE-2020339

摘要:

Soil is the foundation for sustainable food production and environmental protection. Created by unsustainable land management practices and a range of social, economic and environmental drivers, soil degradation and pollution have been an ongoing threat to international food security and environmental quality. Soil degradation and pollution assessments are, however, often focused on the soil itself with little scope to devise new soil management approaches that match food production systems and/or environmental protection. This study draws lessons from an Australia-China Joint Research Center Program, Healthy Soils for Sustainable Food Production and Environmental Quality: a research platform that has brought together multi-disciplinary approaches from world-renowned universities and research organizations in Australia and China. To this end, a framework is presented for future soil management in a new way that combines excellence in research, industry and policymakers in a partnership that will ensure not only the right focus of the research but also that high-quality outputs will be transferable to industry and end-users.

关键词: Australia     China     environmental quality     food production     healthy soils    

vanadium-bearing resources in the preparation of rare-earth vanadate catalysts for semi-hydrogenation of ,-unsaturated

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1793-1806 doi: 10.1007/s11705-022-2191-x

摘要: Recycling industrial solid waste not only saves resources but also eliminates environmental concerns of toxic threats. Herein, we proposed a new strategy for the utilization of petrochemical-derived carbon black waste, a waste vanadium-bearing resource (V > 30000 ppm (10 −6)). Chemical leaching was employed to extract metallic vanadium from the waste and the leachate containing V was used as an alternative raw material for the fabrication of vanadate nanomaterials. Through the screening of various metal cations, it was found that the contaminated Na+ during the leaching process showed strong competitive coordination with the vanadium ions. However, by adding foreign Ce3+ and Y3+ cations, two rare-earth vanadates, viz., flower-like CeVO4 and spherical YVO4 nanomaterials, were successfully synthesized. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier-transform infrared, and N2 physisorption were applied to analyze the physicochemical properties of the waste-derived nanomaterials. Importantly, we found that rare-earth vanadate catalysts exhibited good activities toward the semi-hydrogenation of α,β-unsaturated aldehydes. The conversion of cinnamaldehyde and cinnamic alcohol selectivity were even higher than those of the common CeVO4 prepared using pure chemicals (67.2% vs. 27.7% and 88.4% vs. 53.5%). Our work provides a valuable new reference for preparing vanadate catalysts by the use of abundant vanadium-bearing waste resources.

关键词: petrochemical solid wastes     vanadium recovery     resource utilization     nanomaterials     semi-hydrogenation    

Experimental study of two saturated natural soils and their saturated remoulded soils under three consolidated

Mingjing JIANG, Haijun HU, Jianbing PENG, Serge LEROUEIL

《结构与土木工程前沿(英文)》 2011年 第5卷 第2期   页码 225-238 doi: 10.1007/s11709-011-0108-8

摘要: In this paper, an experimental investigation is conducted to study the mechanical behavior of saturated natural loess, saturated natural filling in ground fissure and their corresponding saturated remoulded soils under three consolidated undrained triaxial stress tests, namely, conventional triaxial compression test (CTC), triaxial compression test (TC) and reduced triaxial compression test (RTC). The test results show that stress-strain relation, i.e. strain-softening or strain-hardening, is remarkably influenced by the structure, void ratio, stress path and confining pressure. Natural structure, high void ratio, TC stress path, RTC stress path and low confining pressures are favorable factors leading to strain-softening. Excess pore pressure during shearing is significantly affected by stress path. The tested soils are different from loose sand on character of strain-softening and are different from common clay on excess pore water pressure behavior. The critical states in ′– space in CTC, TC and RTC tests almost lie on one line, which indicates that the critical state is independent of the above stress paths. As for remoulded loess or remoulded filling, the critical state line (CSL) and isotropic consolidation line (ICL) in -log ′ space are almost straight, while for natural loess or natural filling, in -log ′ space there is a turning point on the CSL, which is similar to the ICL.

关键词: stress paths     static liquefaction     natural soil     remoulded soil     loess     structure     total strength indices     excess pore pressure    

Factors affecting the distribution of microplastics in soils of China

《环境科学与工程前沿(英文)》 2023年 第17卷 第9期 doi: 10.1007/s11783-023-1710-4

摘要:

● Microplastic (MP) abundance in soil of China was highly heterogeneous.

关键词: Microplastic distribution     Microplastic heterogeneity     Effecting factors     Agriculture     Socio-economic factors    

标题 作者 时间 类型 操作

Determination of effective stress parameter of unsaturated soils: A Gaussian process regression approach

Pijush Samui, Jagan J

期刊论文

Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

Nabarun DEY, Aniruddha SENGUPTA

期刊论文

非饱和土的塑性体应变与剪应变的相互作用原理

王靖涛

期刊论文

Behavior of materials for earth and rockfill dams: Perspective from unsaturated soil mechanics

Eduardo E. ALONSO, Rafaela CARDOSO,

期刊论文

Application of fractal theory to unsaturated soil mechanics

XU Yongfu, TONG Lixin

期刊论文

Soil-water interaction in unsaturated expansive soil slopes

ZHAN Liangtong

期刊论文

Stability analysis of layered slopes in unsaturated soils

Guangyu DAI; Fei ZHANG; Yuke WANG

期刊论文

Assessment of future climate change impacts on water-heat-salt migration in unsaturated frozen soil using

Hanli Wan, Jianmin Bian, Han Zhang, Yihan Li

期刊论文

Stable expression and control parameters in the numerical simulation of unsaturated flow

Zhiyuan ZHANG; Xu LI; Yongkang WU; Xiaokang LI

期刊论文

Assessment of pollution of potentially harmful elements in soils surrounding a municipal solid waste

Ying Han, Huiting Xie, Wenbin Liu, Haifeng Li, Mengjing Wang, Xuebin Chen, Xiao Liao, Nan Yan

期刊论文

Carbon-doped surface unsaturated sulfur enriched CoS@rGO aerogel pseudocapacitive anode and biomass-derived

期刊论文

Healthy soils for sustainable food production and environmental quality

Xia LIANG, Jizheng HE, Fusuo ZHANG, Qirong SHEN, Jinshui WU, Iain M. YOUNG, Anthony G. O´DONNELL, Ligang WANG, Enli WANG, Julian HILL, Deli CHEN

期刊论文

vanadium-bearing resources in the preparation of rare-earth vanadate catalysts for semi-hydrogenation of ,-unsaturated

期刊论文

Experimental study of two saturated natural soils and their saturated remoulded soils under three consolidated

Mingjing JIANG, Haijun HU, Jianbing PENG, Serge LEROUEIL

期刊论文

Factors affecting the distribution of microplastics in soils of China

期刊论文