The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clu...The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum disulfide.The unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active sites.Among them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical calculation.Whereupon,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials.展开更多
In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distanc...In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still unclear.Besides,wetting front migration distance and leaching time are usually required to optimize the leaching process.In this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head height.At the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were identical.At the postintersection stage,the intersection accelerated the wetting front migration.By using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the intersection.Finally,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was established.Error analysis results showed that the proposed model can accurately simulate the infiltration process under experimental conditions.The research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.展开更多
In order to enhance the area throughput of next generation wireless local area network(WLAN)in high density scenarios,orthogonal frequency division multiple access(OFDMA)has been adopted as one of the key technologies...In order to enhance the area throughput of next generation wireless local area network(WLAN)in high density scenarios,orthogonal frequency division multiple access(OFDMA)has been adopted as one of the key technologies in the next generation WLAN communication standards.However,the performance of the existing media access control(MAC)degrades significantly under unsaturated services.Therefore,this paper proposes a multi-user parallel contention channel MAC(MU-MAC)based on unsaturated services,which can effectively reduce the channel access conflict and improve the OFDMA access efficiency of cluster member nodes.On this basis,MU-MAC is enhanced for the spatial clustering group(SCG)formation protocol and support for the unsaturated service characteristics.Further,the optimal access radius when the service is in a non-saturated state is analyzed to make the relevant theoretical analysis more generally,and the expressions for the throughput and area throughput of the proposed protocol are modeled and derived.The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance.The results show that MU-MAC outperforms IEEE 802.11ax and OMAX protocol in area throughput by 40.72%and 104.15%,respectively.展开更多
In practical engineering,the total vertical stress in the soil layer is not constant due to stress diffusion,and varies with time and depth.Therefore,the purpose of this paper is to investigate the effect of stress di...In practical engineering,the total vertical stress in the soil layer is not constant due to stress diffusion,and varies with time and depth.Therefore,the purpose of this paper is to investigate the effect of stress diffusion on the two-dimensional(2D)plane strain consolidation properties of unsaturated soils when the stress varies with time and depth.A series of semi-analytical solutions in terms of excess pore air and water pressures and settlement for 2D plane strain consolidation of unsaturated soils can be derived with the joint use of Laplace transform and Fourier sine series expansion.Then,the inverse Laplace transform of the semi-analytical solution is given in the time domain using a self-programmed code based on Crump’s method.The reliability of the obtained solutions is proved by the degeneration.Finally,the 2D plots of excess pore pressures and the curves of settlement varying with time,considering different physical parameters of unsaturated soil stratum and depth-dependent stress,are depicted and analyzed to study the 2D plane strain consolidation properties of unsaturated soils subjected to the depthdependent stress.展开更多
Salinization and desertification are closely related to water-salt migration caused by a temperature gradient.Based on the Darcy Law of unsaturated soils,the law of energy conservation and the law of mass conservation...Salinization and desertification are closely related to water-salt migration caused by a temperature gradient.Based on the Darcy Law of unsaturated soils,the law of energy conservation and the law of mass conservation,the thermal-water-salt coupling mathematical model of unsaturated frozen saline soil was established.The model considered the latent heat of phase change,crystallization impedance,crystallization consumption and complete precipitation of solute crystallization in ice.In order to verify the rationality of the model,the unidirectional freezing test of unsaturated saline soil was carried out in an open system with no-pressure water supplement to obtain the spatial distribution of temperature,moisture and salt in the saline soil.Finally,numerical simulations are implemented with the assistance of COMSOL Multiphysics.Validation of the model is illustrated by comparisons between the simulation and experimental data.The results demonstrated that the temperature within saline soil changes with time and can be divided into three stages,namely quick freezing stage,transitional stage and stable stage.The water and salt contents in the freezing zone are layered,with peak values at the freezing front.The coupled model could reveal the heat-mass migration mechanism of unsaturated frozen saline soil and dynamically describe the freezing depth and the movement law of the freezing front,ice and salt crystal formation mechanism,and the change law of thermal conductivity and permeability coefficient.展开更多
Unsaturated expansive soil is widely distributed in China and has complex engineering properties.This paper proposes the unified hydraulic effect shear strength theory of unsaturated expansive soil based on the effect...Unsaturated expansive soil is widely distributed in China and has complex engineering properties.This paper proposes the unified hydraulic effect shear strength theory of unsaturated expansive soil based on the effective stress principle,swelling force principle,and soil–water characteristics.Considering the viscoelasticity and structural damage of unsaturated expansive soil during loading,a fractional hardening–damage model of unsaturated expansive soil was established.The model parameters were established on the basis of the proposed calculation method of shear strength and the triaxial shear experiment on unsaturated expansive soil.The proposed model was verified by the experimental data and a traditional damage model.The proposed model can satisfactorily describe the entire process of the strain-hardening law of unsaturated expansive soil.Finally,by investigating the damage variables of the proposed model,it was found that:(a)when the values of confining pressure and matric suction are close,the coupling of confining pressure and matric suction contributes more to the shear strength;(b)there is a damage threshold for unsaturated expansive soil,and is mainly reflected by strength criterion of infinitesimal body;(c)the strain hardening law of unsaturated expansive soil is mainly reflected by fractional derivative operator.展开更多
Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock,and it also plays important roles in safety and capacity of CO_(2)geological storage.Based on the published experimental results...Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock,and it also plays important roles in safety and capacity of CO_(2)geological storage.Based on the published experimental results,we present numerical simulations on CO_(2)breakthrough pressure in unsaturated low-permeability rock under 9 multiple P-T conditions(which can keep CO_(2)in gaseous,liquid and supercritical states)and thus,a numerical method which can be used to accurately predict CO_(2)breakthrough pressure on rock-core scale is proposed.The simulation results show that CO_(2)breakthrough pressure and breakthrough time are exponential correlated with P-T conditions.Meanwhile,pressure has stronger effects on experimental results than that of temperature.Moreover,we performed sensitivity studies on the pore distribution indexλ(0.6,0.7,0.8,and 0.9)in van Genuchten-Muale model.Results show that with the increase ofλ,CO_(2)breakthrough pressure and breakthrough time both show decreasing trends.In other words,the larger the value ofλis,the better the permeability of the caprock is,and the worse the CO_(2)sealing capacity is.The numerical method established in this study can provide an important reference for the prediction of gas breakthrough pressure on rock-core scale and for related numerical studies.展开更多
Adiponectin,a specific hormone protein secreted by adipocytes,is a protective factor in the human body and has attracted great attention due to its anti-obesity activity[1,2].The adiponectin gene(ADIPOQ),which is loca...Adiponectin,a specific hormone protein secreted by adipocytes,is a protective factor in the human body and has attracted great attention due to its anti-obesity activity[1,2].The adiponectin gene(ADIPOQ),which is located on human chromosome 3q27,is a single-copy gene.Various single-nucleotide polymorphisms(SNPs)of the human ADIPOQ play an important role in energy balance and are associated with body mass index(BMI)and obesity[3,4].Longchain polyunsaturated fatty acids(LC-PUFAs)have been identified to exert an important role during the first 1,000 days of life on infant growth,neurodevelopment,and visual acuity.Fatty acids,such asα-linoleic acid(ALA,C18:3n-3)and linoleic acid(LA,C18:2n-6),which cannot be synthesized de novo from other lipids,are necessary for biological reactions.Some fatty acids such as docosahexaenoic acid(DHA,C22:6n-3)and eicosapentaenoic acid(EPA,C20:5n-3)can be synthesized in neonates from their precursors(LA and ALA).Because of the very low conversion rates in the neonatal liver,it is crucial to provide adequate LC-PUFAs in the diet from early infancy.展开更多
We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recentl...We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recently(Z.Zheng,Journal of Fluid Mechanics,950,A17,2022).Based on the assumption of vertical gravitational-capillary equilibrium,the saturation distribution and profile shape of the invading fluid can be obtained by solving a nonlinear integral-differential equation.The capillary pressure curves p_(c)(s)can then be constructed by systematically varying the injection rate.Together with the relative permeability curves k_(rn)(s)that are already obtained.One can now provide quick estimates on the overall behaviours of interfacial and unsaturated flows in vertically-heterogeneous porous layers.展开更多
This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experi...This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experiments were used to determine the optimal combination of parameters.In particular,an erosion device con-sisting of a motor with a constantflow rate of 45 L/min,a pump with a diameter of 40 mm,a nozzle with a dia-meter of 5 mm,and a tank made of“perspex glass”55 cm long,30 cm tall,and 25 cm wide was used.The tests were conducted by varying the sample-to-nozzle distance,the pattern angle,and the sand particle size.The results have revealed that the presence of 7.5%by weight of waste coconut shell,for conditions corresponding to 90°angle,sand size 425μm,stand distance 30 cm,gives the best wear resistance(3.04×10^(-5) g/g).Thefiller content and sand particle size affect the erosive rate,with the angle playing a secondary role.The distance between the sample and the nozzle has a weaker effect on erosive wear.The hardness results show that the models(UP-5%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste coconut shell)give the best values for prayer compared to the samples(UP-5 wt.%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste walnut shell).展开更多
A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition m...A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .展开更多
AIM: To investigate how the saturated and unsaturated fatty acid composition influences the susceptibility of developing acute pancreatitis. METHODS: Primary pancreatic acinar cells were treated with low and high conc...AIM: To investigate how the saturated and unsaturated fatty acid composition influences the susceptibility of developing acute pancreatitis. METHODS: Primary pancreatic acinar cells were treated with low and high concentrations of different saturated and unsaturated fatty acids, and changes in the cytosolic Ca2+ signal and the expression of protein kinase C(PKC) were measured after treatment. RESULTS: Unsaturated fatty acids at high concentrations, including oleic acid, linoleic acid, palmitoleic acid, docosahexaenoic acid, and arachidonic acid, induced a persistent rise in cytosolic Ca2+ concentrations in acinar cells. Unsaturated fatty acids at low concentrations and saturated fatty acids, including palmitic acid, stearic acid, and triglycerides, at low and high concentrations were unable to induce a rise in Ca2+ concentrations in acinar cells. Unsaturated fatty acids at high concentrations but not saturated fatty acids induced intra-acinar cell trypsin activation and cell damage and increased PKC expression.CONCLUSION: At sufficiently high concentrations, unsaturated fatty acids were able to induce acinar cells injury and promote the development of pancreatitis. Unsaturated fatty acids may play a distinctive role in the pathogenesis of pancreatitis through the activation of PKC family members.展开更多
Generally, most soil slope failures are induced by rainfall infiltration, a process that involves interactions between the liquid phase, gas phase,and solid skeleton in an unsaturated soil slope. In this study, a loos...Generally, most soil slope failures are induced by rainfall infiltration, a process that involves interactions between the liquid phase, gas phase,and solid skeleton in an unsaturated soil slope. In this study, a loosely coupled liquid-gas-solid three-phase model, linking two numerical codes,TOUGH2/EOS3, which is used for water-air two-phase flow analysis, and FLAC^(3D), which is used for mechanical analysis, was established. The model was validated through a documented water drainage experiment over a sandy column and a comparison of the results with measured data and simulated results from other researchers. The proposed model was used to investigate the features of water-air two-phase flow and stress fields in an unsaturated soil slope during rainfall infiltration. The slope stability analysis was then performed based on the simulated water-air two-phase seepage and stress fields on a given slip surface. The results show that the safety factor for the given slip surface decreases first, then increases, and later decreases until the rainfall stops. Subsequently, a sudden rise occurs. After that, the safety factor decreases continually and reaches its lowest value, and then increases slowly to a steady value. The lowest value does not occur when the rainfall stops, indicating a delayed effect of the safety factor. The variations of the safety factor for the given slip surface are therefore caused by a combination of pore-air pressure, matric suction, normal stress, and net normal stress.展开更多
AIM:To investigate the relationship between the metabolism of polyunsaturated fatty acids(PUFAs)andtumor-associated factors for predicting the outcome of colorectal carcinoma(CRC)in Chinese patients.METHODS:Fresh-froz...AIM:To investigate the relationship between the metabolism of polyunsaturated fatty acids(PUFAs)andtumor-associated factors for predicting the outcome of colorectal carcinoma(CRC)in Chinese patients.METHODS:Fresh-frozen malignant and normal tissues from 82 Chinese patients with CRC were analyzed for PUFA composition using gas-liquid chromatography.The levels of vascular endothelial growth factor(VEGF),cyclooxygenase-2(COX-2),prostaglandin E2 and platelet-derived growth factor(PDGF)were measured by enzyme-linked immunosorbent assay,and the levels of VEGF,p53 and Ki-67 were measured by immunohistochemistry.RESULTS:In malignant tissue,compared with normal tissue,the levels of totalω-6 PUFAs(24.64%±3.41%vs 26.77%±3.37%,P=0.00)and linoleic acid(LA)(15.46%±3.51%vs 18.30%±2.83%,P<0.01)were lower,whereas the levels of totalω-3 PUFAs(1.58%±0.74%vs 1.35%±0.60%,P<0.01)and dihomo-gamma-linolenic acid(DGLA)(1.32%±0.69%vs 0.85%±0.29%,P<0.01)were significantly higher.The ratios of arachidonic acid(AA)/LA(0.53±0.22 vs0.42±0.19,P<0.01)and AA/totalω-6 PUFAs(0.31±0.09 vs 0.27±0.10,P<0.01)were also significantly higher in malignant tissue.The levels of PDGF(353.10±148.85 pg/m L vs 286.09±104.91 pg/m L,P<0.01),COX-2(125.21±70.29 ng/m L vs 67.06±42.22 ng/m L,P<0.01)and VEGF(357.11±128.76 pg/m L vs211.38±99.47 pg/m L,P<0.01)were also higher in malignant tissue compared to normal tissue.COX-2was inversely correlated with LA(R=-0.3244,P<0.05)and positively correlated with AA/totalω-6 PUFAs(R=0.3083,P<0.05)and AA/LA(R=0.3001,P<0.05).The tissue level of LA was highest in poorly differentiated tumors(19.9%±6.3%,P<0.05),while the ratio of AA/ω-3 PUFAs was lowest in these tumors(10.8±2.6,P<0.05).In VEGF-positive tumors,the level of LA was higher(16.2%±3.7%vs 13.9%±2.7%,P<0.01),while the AA/ω-3PUFA,AA/ω-6 PUFA,and AA/LA ratios were lower than in VEGF-negativetumors(5.0±1.8 vs 6.7±3.3,0.30±0.09 vs 0.34±0.09,0.50±0.21 vs 0.61±0.21,P<0.01).CONCLUSION:The metabolism of PUFAs may playan important role in the evolution of inflammationdriven tumorigenesis in CRC and may be considered apotential marker for prognosis.展开更多
Four ternary lanthanide complexes with unsaturated acid and 1,10-phenanthroline are prepared in methanol and characterized by elemental analysis, molar conductance, UV, IR, （（）1H） NMR and XPS. The results from thi...Four ternary lanthanide complexes with unsaturated acid and 1,10-phenanthroline are prepared in methanol and characterized by elemental analysis, molar conductance, UV, IR, （（）1H） NMR and XPS. The results from this paper show that the complexes Ln（phen）（SA）3·2H2O or Ln（phen）（CA）3·H2O （Ln=Ce（Ⅲ）, Sm（Ⅲ） and Eu（Ⅲ）, （phen=1,10-）phenanthroline, SA=Sorbate and CA=Cinnamate） has better anti-inflammatory effect than cerium nitrate and their gremores are steadier than cerium nitrate gremor. And there is a kind of medicament which can replace the cerium nitrate gremor completely in treating burn.展开更多
A constitutive model of unsaturated soils with coupling capillary hysteresis and skeleton deformation is developed and implemented in a fully coupled transient hydro-mechanical finite-element model(computer code U-DYS...A constitutive model of unsaturated soils with coupling capillary hysteresis and skeleton deformation is developed and implemented in a fully coupled transient hydro-mechanical finite-element model(computer code U-DYSAC2).The obtained results are compared with experimental results,showing that the proposed constitutive model can simulate the main mechanical and hydraulic behavior of unsaturated soils in a unified framework.The non-linearity of the soil-water characteristic relation is treated in a similar way of elastoplasticity.Two constitutive relations are integrated by an implicit return-mapping scheme similar to that developed for saturated soils.A consistent tangential modulus is derived to preserve the asymptotic rate of the quadratic convergence of Newton's iteration.Combined with the integration of the constitutive model,a complete finite-element formulation of coupling hydro-mechanical problems for unsaturated soils is presented.A number of practical problems with different given initial and boundary conditions are analyzed to illustrate the performance and capabilities of the finite-element model.展开更多
Based on the principle of saturated infiltration and the Green-Ampt model,an unsaturated infiltration model for a soil slope surface was established for either constant moisture content,or depth-varying moisture conte...Based on the principle of saturated infiltration and the Green-Ampt model,an unsaturated infiltration model for a soil slope surface was established for either constant moisture content,or depth-varying moisture content and the slope.Infiltration parameters in the partially saturated slope were revealed under sustained rainfall.Through analysis of the variation of initial moisture content in the slope,the ponding time,infiltration depth,and infiltration rate were deduced for an unsaturated soil slope subject to rainfall infiltration.There is no ponded water on the surface of the slope under sustained low-intensity rainfall.The results show that the infiltration parameters of an unsaturated slope are influenced by the initial moisture content and the wetting front saturation,the soil cohesion and rainfall intensity under sustained rainfall.More short-term slope failures can occur with the decrease of cohesion of the soil of the slope.The ponding time and infiltration depth differ considering constant or different initial moisture content respectively in the soil slope.Then,best-fit curves of the infiltration rate,ponding time,and infiltration depth to the wetting front saturation were obtained with constant or different initial moisture contents.And the slope failure time is roughly uniform when subject to a rainfall intensity I>5 mm/h.展开更多
Mortierella isabellina was found to accumulate large amounts of unsaturated fatty acids when it was grown in a medium containing butanol(5 g/L) and yeast extract(10 g/L) and cultivated at 25 ℃ for 5 d during which ad...Mortierella isabellina was found to accumulate large amounts of unsaturated fatty acids when it was grown in a medium containing butanol(5 g/L) and yeast extract(10 g/L) and cultivated at 25 ℃ for 5 d during which additional feeding butanol of 2 g/L was fed after being cultivated for 48 h . The resultant mycelial lipids accounted for 40 1% of the dry mycelia, while about 34% of butanol in the medium was converted. The mycelial lipids contained four kinds of unsaturated fatty acids, i.e ., palmitoleic(4 9%), oleic(54 1%), linoleic(10 4%) and linolenic(5 4%) acids. Those accounted for 74 8% of the total fatty acids. The effects of the culture conditions, such as cultivation temperature, initial pH of the medium and additional feeding butanol in the course of cultivation, on the production of mycelial lipids by M. isabellina were studied.展开更多
Modeling unsaturated flow in fractured rocks is essential in various subsurface engineering applications,but it remains a great challenge due to the difficulties in determining the unsaturated hydraulic properties of ...Modeling unsaturated flow in fractured rocks is essential in various subsurface engineering applications,but it remains a great challenge due to the difficulties in determining the unsaturated hydraulic properties of rocks that contain various scales of fractures.It is generally accepted that the van Genuchten(VG)model can be applied to fractured rocks,provided that the hydraulic parameters could be representatively determined.In this study,scaling relationships between the VG parameters(a and n)and hydraulic conductivity(K)across 8 orders of magnitude,from 10^(-10)m/s to 10^(-2)m/s,were proposed by statistical analysis of data obtained from 1416 soil samples.The correlations were then generalized to predict the upper bounds of VG parameters for fractured rocks from the K data that could be obtained more easily under field conditions,and were validated against a limited set of data from cores,fractures and fractured rocks available in the literature.The upper bound estimates significantly narrow the ranges of VG parameters,and the representative values of a and n for fractured rocks at the field scale can then be determined with confidence by inverse modeling using groundwater observations in saturated zones.The proposed methodology was applied to saturated-unsaturated flow modeling in the right-bank slope at the Baihetan dam site with a continuum approach,showing that most of the flow behaviors in fractured rocks in this complex hydrogeological condition could be properly reproduced.The proposed method overcomes difficulties in suction measurement in fractured rocks with strong heterogeneity,and provides a feasible way for modeling of saturated-unsaturated flow in fractured rocks with acceptable engineering accuracy.展开更多
Two modifications for the basic Barcelona model(BBM) are present. One is the replacement of the net stress by the average skeleton stress in unsaturated soil modeling, and the other is the adoption of an expression fo...Two modifications for the basic Barcelona model(BBM) are present. One is the replacement of the net stress by the average skeleton stress in unsaturated soil modeling, and the other is the adoption of an expression for the load-collapse(LC) yield surface that can match flexibly the normal compression lines at different suctions. The predictions of the modified BBM for the controlled-suction triaxial test on the unsaturated compacted clay are presented and compared with the experimental results. A good agreement between the predicted and experimental results demonstrates the reasonability of the modified BBM. On this basis, the coupled processes of groundwater flow and soil deformation in a homogeneous soil slope under a long heavy rainfall are simulated with the proposed elasto-plastic model. The numerical results reveal that the failure of a slope under rainfall infiltration is due to both the reduction of soil suction and the significant rise in groundwater table. The evolution of the displacements is greatly related to the change of suction. The maximum collapse deformation happens near the surface of slope where infiltrated rainwater can quickly reach. The results may provide a helpful reference for hazard assessment and control of rainfall-induced landslides.展开更多
基金supported by the National Natural Science Foundation of China(22205209,52202373 and U21A200972)China Postdoctoral Science Foundation(2022M722867)Key Research Project of Higher Education Institutions in Henan Province(23A530001)。
文摘The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum disulfide.The unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active sites.Among them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical calculation.Whereupon,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials.
基金This research was funded by the National Natural Science Foundation of China(Grant No.52174113)the Young Jinggang Scholars Award Program in Jiangxi Province,China(Grant No.QNJG2018051)the“Thousand Talents”of Jiangxi Province,China(Grant No.jxsq2019201043).
文摘In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still unclear.Besides,wetting front migration distance and leaching time are usually required to optimize the leaching process.In this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head height.At the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were identical.At the postintersection stage,the intersection accelerated the wetting front migration.By using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the intersection.Finally,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was established.Error analysis results showed that the proposed model can accurately simulate the infiltration process under experimental conditions.The research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.
基金supported by the 13th Five-Year National Key Research and Development Plan of China (2016YFD0300609)the Outstanding Science and Technology Innovation Talents Program of Henan province (184200510008)+4 种基金Modern Agricultural Technology System Project of Henan Province (S2010-01G04)the National Key Research and Development Program of China (2017YFD0301105)the National Natural Science Foundations of CHINA (Grant No. 61501373, No. 61771390, No. 61771392, No. 61871322, and No. 61271279)the Henan Province Key Scientific and Technological Project (182102110291 and 222102110234)Natural Science Foundation of Henan Province (232300420186)
文摘In order to enhance the area throughput of next generation wireless local area network(WLAN)in high density scenarios,orthogonal frequency division multiple access(OFDMA)has been adopted as one of the key technologies in the next generation WLAN communication standards.However,the performance of the existing media access control(MAC)degrades significantly under unsaturated services.Therefore,this paper proposes a multi-user parallel contention channel MAC(MU-MAC)based on unsaturated services,which can effectively reduce the channel access conflict and improve the OFDMA access efficiency of cluster member nodes.On this basis,MU-MAC is enhanced for the spatial clustering group(SCG)formation protocol and support for the unsaturated service characteristics.Further,the optimal access radius when the service is in a non-saturated state is analyzed to make the relevant theoretical analysis more generally,and the expressions for the throughput and area throughput of the proposed protocol are modeled and derived.The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance.The results show that MU-MAC outperforms IEEE 802.11ax and OMAX protocol in area throughput by 40.72%and 104.15%,respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172211 and 41630633)the National Key Research and Development Project of China(Grant No.2019YFC1509800).
文摘In practical engineering,the total vertical stress in the soil layer is not constant due to stress diffusion,and varies with time and depth.Therefore,the purpose of this paper is to investigate the effect of stress diffusion on the two-dimensional(2D)plane strain consolidation properties of unsaturated soils when the stress varies with time and depth.A series of semi-analytical solutions in terms of excess pore air and water pressures and settlement for 2D plane strain consolidation of unsaturated soils can be derived with the joint use of Laplace transform and Fourier sine series expansion.Then,the inverse Laplace transform of the semi-analytical solution is given in the time domain using a self-programmed code based on Crump’s method.The reliability of the obtained solutions is proved by the degeneration.Finally,the 2D plots of excess pore pressures and the curves of settlement varying with time,considering different physical parameters of unsaturated soil stratum and depth-dependent stress,are depicted and analyzed to study the 2D plane strain consolidation properties of unsaturated soils subjected to the depthdependent stress.
基金supported by the Special Funds for Guiding Local Scientific and Technological Development by The Central Government(22ZY1QA005)the Science and Technology Program of Gansu Province"Outstanding Doctoral Students Project"(22JR5RA325)+3 种基金"Innovation Star"Funding Project for Outstanding Graduate Students of Gansu Province(2022CXZX-528)the Science and Technology Project of Gansu Province(21YF5GA050)Education Department of Gansu Province Industrial Support Plan Project(2021CYZC-28)Transport Department of Gansu Province Science and Technology R&D Projects(No.2021-12).
文摘Salinization and desertification are closely related to water-salt migration caused by a temperature gradient.Based on the Darcy Law of unsaturated soils,the law of energy conservation and the law of mass conservation,the thermal-water-salt coupling mathematical model of unsaturated frozen saline soil was established.The model considered the latent heat of phase change,crystallization impedance,crystallization consumption and complete precipitation of solute crystallization in ice.In order to verify the rationality of the model,the unidirectional freezing test of unsaturated saline soil was carried out in an open system with no-pressure water supplement to obtain the spatial distribution of temperature,moisture and salt in the saline soil.Finally,numerical simulations are implemented with the assistance of COMSOL Multiphysics.Validation of the model is illustrated by comparisons between the simulation and experimental data.The results demonstrated that the temperature within saline soil changes with time and can be divided into three stages,namely quick freezing stage,transitional stage and stable stage.The water and salt contents in the freezing zone are layered,with peak values at the freezing front.The coupled model could reveal the heat-mass migration mechanism of unsaturated frozen saline soil and dynamically describe the freezing depth and the movement law of the freezing front,ice and salt crystal formation mechanism,and the change law of thermal conductivity and permeability coefficient.
基金financially supported by Sichuan Huaxi Group Co.,ltd.(No.HXKX2019/015,No.HXKX2019/019,No.HXKX2018/030)the Open Fund of Sichuan Provincial Engineering Research Center of City Solid Waste Energy and Building Materials Conversion and Utilization Technology(No.GF2022ZC009)the Open Fund of Sichuan Engineering Research Center for Mechanical Properties and Engineering Technology of Unsaturated Soils(No.SC-FBHT2022-04)。
文摘Unsaturated expansive soil is widely distributed in China and has complex engineering properties.This paper proposes the unified hydraulic effect shear strength theory of unsaturated expansive soil based on the effective stress principle,swelling force principle,and soil–water characteristics.Considering the viscoelasticity and structural damage of unsaturated expansive soil during loading,a fractional hardening–damage model of unsaturated expansive soil was established.The model parameters were established on the basis of the proposed calculation method of shear strength and the triaxial shear experiment on unsaturated expansive soil.The proposed model was verified by the experimental data and a traditional damage model.The proposed model can satisfactorily describe the entire process of the strain-hardening law of unsaturated expansive soil.Finally,by investigating the damage variables of the proposed model,it was found that:(a)when the values of confining pressure and matric suction are close,the coupling of confining pressure and matric suction contributes more to the shear strength;(b)there is a damage threshold for unsaturated expansive soil,and is mainly reflected by strength criterion of infinitesimal body;(c)the strain hardening law of unsaturated expansive soil is mainly reflected by fractional derivative operator.
基金supported by Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME021010)funded by the National Natural Science Foundation of China(Grant No.41702251 and 42141010)the MOE Key Laboratory of Groundwater Circulation and Environmental Evolution。
文摘Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock,and it also plays important roles in safety and capacity of CO_(2)geological storage.Based on the published experimental results,we present numerical simulations on CO_(2)breakthrough pressure in unsaturated low-permeability rock under 9 multiple P-T conditions(which can keep CO_(2)in gaseous,liquid and supercritical states)and thus,a numerical method which can be used to accurately predict CO_(2)breakthrough pressure on rock-core scale is proposed.The simulation results show that CO_(2)breakthrough pressure and breakthrough time are exponential correlated with P-T conditions.Meanwhile,pressure has stronger effects on experimental results than that of temperature.Moreover,we performed sensitivity studies on the pore distribution indexλ(0.6,0.7,0.8,and 0.9)in van Genuchten-Muale model.Results show that with the increase ofλ,CO_(2)breakthrough pressure and breakthrough time both show decreasing trends.In other words,the larger the value ofλis,the better the permeability of the caprock is,and the worse the CO_(2)sealing capacity is.The numerical method established in this study can provide an important reference for the prediction of gas breakthrough pressure on rock-core scale and for related numerical studies.
文摘Adiponectin,a specific hormone protein secreted by adipocytes,is a protective factor in the human body and has attracted great attention due to its anti-obesity activity[1,2].The adiponectin gene(ADIPOQ),which is located on human chromosome 3q27,is a single-copy gene.Various single-nucleotide polymorphisms(SNPs)of the human ADIPOQ play an important role in energy balance and are associated with body mass index(BMI)and obesity[3,4].Longchain polyunsaturated fatty acids(LC-PUFAs)have been identified to exert an important role during the first 1,000 days of life on infant growth,neurodevelopment,and visual acuity.Fatty acids,such asα-linoleic acid(ALA,C18:3n-3)and linoleic acid(LA,C18:2n-6),which cannot be synthesized de novo from other lipids,are necessary for biological reactions.Some fatty acids such as docosahexaenoic acid(DHA,C22:6n-3)and eicosapentaenoic acid(EPA,C20:5n-3)can be synthesized in neonates from their precursors(LA and ALA).Because of the very low conversion rates in the neonatal liver,it is crucial to provide adequate LC-PUFAs in the diet from early infancy.
基金by the Program for Professor of Special Appointment(Eastern Scholar,No.TP2020009)at Shanghai Institutions of Higher Learning。
文摘We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recently(Z.Zheng,Journal of Fluid Mechanics,950,A17,2022).Based on the assumption of vertical gravitational-capillary equilibrium,the saturation distribution and profile shape of the invading fluid can be obtained by solving a nonlinear integral-differential equation.The capillary pressure curves p_(c)(s)can then be constructed by systematically varying the injection rate.Together with the relative permeability curves k_(rn)(s)that are already obtained.One can now provide quick estimates on the overall behaviours of interfacial and unsaturated flows in vertically-heterogeneous porous layers.
文摘This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experiments were used to determine the optimal combination of parameters.In particular,an erosion device con-sisting of a motor with a constantflow rate of 45 L/min,a pump with a diameter of 40 mm,a nozzle with a dia-meter of 5 mm,and a tank made of“perspex glass”55 cm long,30 cm tall,and 25 cm wide was used.The tests were conducted by varying the sample-to-nozzle distance,the pattern angle,and the sand particle size.The results have revealed that the presence of 7.5%by weight of waste coconut shell,for conditions corresponding to 90°angle,sand size 425μm,stand distance 30 cm,gives the best wear resistance(3.04×10^(-5) g/g).Thefiller content and sand particle size affect the erosive rate,with the angle playing a secondary role.The distance between the sample and the nozzle has a weaker effect on erosive wear.The hardness results show that the models(UP-5%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste coconut shell)give the best values for prayer compared to the samples(UP-5 wt.%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste walnut shell).
文摘A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .
文摘AIM: To investigate how the saturated and unsaturated fatty acid composition influences the susceptibility of developing acute pancreatitis. METHODS: Primary pancreatic acinar cells were treated with low and high concentrations of different saturated and unsaturated fatty acids, and changes in the cytosolic Ca2+ signal and the expression of protein kinase C(PKC) were measured after treatment. RESULTS: Unsaturated fatty acids at high concentrations, including oleic acid, linoleic acid, palmitoleic acid, docosahexaenoic acid, and arachidonic acid, induced a persistent rise in cytosolic Ca2+ concentrations in acinar cells. Unsaturated fatty acids at low concentrations and saturated fatty acids, including palmitic acid, stearic acid, and triglycerides, at low and high concentrations were unable to induce a rise in Ca2+ concentrations in acinar cells. Unsaturated fatty acids at high concentrations but not saturated fatty acids induced intra-acinar cell trypsin activation and cell damage and increased PKC expression.CONCLUSION: At sufficiently high concentrations, unsaturated fatty acids were able to induce acinar cells injury and promote the development of pancreatitis. Unsaturated fatty acids may play a distinctive role in the pathogenesis of pancreatitis through the activation of PKC family members.
基金supported by the National Natural Science Foundation of China(Grants No.51579170 and 51179118)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51321065)
文摘Generally, most soil slope failures are induced by rainfall infiltration, a process that involves interactions between the liquid phase, gas phase,and solid skeleton in an unsaturated soil slope. In this study, a loosely coupled liquid-gas-solid three-phase model, linking two numerical codes,TOUGH2/EOS3, which is used for water-air two-phase flow analysis, and FLAC^(3D), which is used for mechanical analysis, was established. The model was validated through a documented water drainage experiment over a sandy column and a comparison of the results with measured data and simulated results from other researchers. The proposed model was used to investigate the features of water-air two-phase flow and stress fields in an unsaturated soil slope during rainfall infiltration. The slope stability analysis was then performed based on the simulated water-air two-phase seepage and stress fields on a given slip surface. The results show that the safety factor for the given slip surface decreases first, then increases, and later decreases until the rainfall stops. Subsequently, a sudden rise occurs. After that, the safety factor decreases continually and reaches its lowest value, and then increases slowly to a steady value. The lowest value does not occur when the rainfall stops, indicating a delayed effect of the safety factor. The variations of the safety factor for the given slip surface are therefore caused by a combination of pore-air pressure, matric suction, normal stress, and net normal stress.
文摘AIM:To investigate the relationship between the metabolism of polyunsaturated fatty acids(PUFAs)andtumor-associated factors for predicting the outcome of colorectal carcinoma(CRC)in Chinese patients.METHODS:Fresh-frozen malignant and normal tissues from 82 Chinese patients with CRC were analyzed for PUFA composition using gas-liquid chromatography.The levels of vascular endothelial growth factor(VEGF),cyclooxygenase-2(COX-2),prostaglandin E2 and platelet-derived growth factor(PDGF)were measured by enzyme-linked immunosorbent assay,and the levels of VEGF,p53 and Ki-67 were measured by immunohistochemistry.RESULTS:In malignant tissue,compared with normal tissue,the levels of totalω-6 PUFAs(24.64%±3.41%vs 26.77%±3.37%,P=0.00)and linoleic acid(LA)(15.46%±3.51%vs 18.30%±2.83%,P<0.01)were lower,whereas the levels of totalω-3 PUFAs(1.58%±0.74%vs 1.35%±0.60%,P<0.01)and dihomo-gamma-linolenic acid(DGLA)(1.32%±0.69%vs 0.85%±0.29%,P<0.01)were significantly higher.The ratios of arachidonic acid(AA)/LA(0.53±0.22 vs0.42±0.19,P<0.01)and AA/totalω-6 PUFAs(0.31±0.09 vs 0.27±0.10,P<0.01)were also significantly higher in malignant tissue.The levels of PDGF(353.10±148.85 pg/m L vs 286.09±104.91 pg/m L,P<0.01),COX-2(125.21±70.29 ng/m L vs 67.06±42.22 ng/m L,P<0.01)and VEGF(357.11±128.76 pg/m L vs211.38±99.47 pg/m L,P<0.01)were also higher in malignant tissue compared to normal tissue.COX-2was inversely correlated with LA(R=-0.3244,P<0.05)and positively correlated with AA/totalω-6 PUFAs(R=0.3083,P<0.05)and AA/LA(R=0.3001,P<0.05).The tissue level of LA was highest in poorly differentiated tumors(19.9%±6.3%,P<0.05),while the ratio of AA/ω-3 PUFAs was lowest in these tumors(10.8±2.6,P<0.05).In VEGF-positive tumors,the level of LA was higher(16.2%±3.7%vs 13.9%±2.7%,P<0.01),while the AA/ω-3PUFA,AA/ω-6 PUFA,and AA/LA ratios were lower than in VEGF-negativetumors(5.0±1.8 vs 6.7±3.3,0.30±0.09 vs 0.34±0.09,0.50±0.21 vs 0.61±0.21,P<0.01).CONCLUSION:The metabolism of PUFAs may playan important role in the evolution of inflammationdriven tumorigenesis in CRC and may be considered apotential marker for prognosis.
文摘Four ternary lanthanide complexes with unsaturated acid and 1,10-phenanthroline are prepared in methanol and characterized by elemental analysis, molar conductance, UV, IR, （（）1H） NMR and XPS. The results from this paper show that the complexes Ln（phen）（SA）3·2H2O or Ln（phen）（CA）3·H2O （Ln=Ce（Ⅲ）, Sm（Ⅲ） and Eu（Ⅲ）, （phen=1,10-）phenanthroline, SA=Sorbate and CA=Cinnamate） has better anti-inflammatory effect than cerium nitrate and their gremores are steadier than cerium nitrate gremor. And there is a kind of medicament which can replace the cerium nitrate gremor completely in treating burn.
基金supported by the National Natural Science Foundation of China(No.11072255)the Natural Science Foundation of Guangxi Province(No.2011GXNSFE018004)
文摘A constitutive model of unsaturated soils with coupling capillary hysteresis and skeleton deformation is developed and implemented in a fully coupled transient hydro-mechanical finite-element model(computer code U-DYSAC2).The obtained results are compared with experimental results,showing that the proposed constitutive model can simulate the main mechanical and hydraulic behavior of unsaturated soils in a unified framework.The non-linearity of the soil-water characteristic relation is treated in a similar way of elastoplasticity.Two constitutive relations are integrated by an implicit return-mapping scheme similar to that developed for saturated soils.A consistent tangential modulus is derived to preserve the asymptotic rate of the quadratic convergence of Newton's iteration.Combined with the integration of the constitutive model,a complete finite-element formulation of coupling hydro-mechanical problems for unsaturated soils is presented.A number of practical problems with different given initial and boundary conditions are analyzed to illustrate the performance and capabilities of the finite-element model.
基金sponsored by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY19E080007,No.LY19E080008)the Natural Science Foundation of China(Grant No.51578356)the Science and Technology Fund of Yunnan Provincial Communication Department of China(Grant No.2010(A)06-b)。
文摘Based on the principle of saturated infiltration and the Green-Ampt model,an unsaturated infiltration model for a soil slope surface was established for either constant moisture content,or depth-varying moisture content and the slope.Infiltration parameters in the partially saturated slope were revealed under sustained rainfall.Through analysis of the variation of initial moisture content in the slope,the ponding time,infiltration depth,and infiltration rate were deduced for an unsaturated soil slope subject to rainfall infiltration.There is no ponded water on the surface of the slope under sustained low-intensity rainfall.The results show that the infiltration parameters of an unsaturated slope are influenced by the initial moisture content and the wetting front saturation,the soil cohesion and rainfall intensity under sustained rainfall.More short-term slope failures can occur with the decrease of cohesion of the soil of the slope.The ponding time and infiltration depth differ considering constant or different initial moisture content respectively in the soil slope.Then,best-fit curves of the infiltration rate,ponding time,and infiltration depth to the wetting front saturation were obtained with constant or different initial moisture contents.And the slope failure time is roughly uniform when subject to a rainfall intensity I>5 mm/h.
基金Supported by the National Natural Science Foundation of China(No.2 98730 18)
文摘Mortierella isabellina was found to accumulate large amounts of unsaturated fatty acids when it was grown in a medium containing butanol(5 g/L) and yeast extract(10 g/L) and cultivated at 25 ℃ for 5 d during which additional feeding butanol of 2 g/L was fed after being cultivated for 48 h . The resultant mycelial lipids accounted for 40 1% of the dry mycelia, while about 34% of butanol in the medium was converted. The mycelial lipids contained four kinds of unsaturated fatty acids, i.e ., palmitoleic(4 9%), oleic(54 1%), linoleic(10 4%) and linolenic(5 4%) acids. Those accounted for 74 8% of the total fatty acids. The effects of the culture conditions, such as cultivation temperature, initial pH of the medium and additional feeding butanol in the course of cultivation, on the production of mycelial lipids by M. isabellina were studied.
基金financial supports from the National Natural Science Foundation of China(Grant Nos.51925906 and 51988101)the National Key R&D Program of China(Grant No.2018YFC0407001)。
文摘Modeling unsaturated flow in fractured rocks is essential in various subsurface engineering applications,but it remains a great challenge due to the difficulties in determining the unsaturated hydraulic properties of rocks that contain various scales of fractures.It is generally accepted that the van Genuchten(VG)model can be applied to fractured rocks,provided that the hydraulic parameters could be representatively determined.In this study,scaling relationships between the VG parameters(a and n)and hydraulic conductivity(K)across 8 orders of magnitude,from 10^(-10)m/s to 10^(-2)m/s,were proposed by statistical analysis of data obtained from 1416 soil samples.The correlations were then generalized to predict the upper bounds of VG parameters for fractured rocks from the K data that could be obtained more easily under field conditions,and were validated against a limited set of data from cores,fractures and fractured rocks available in the literature.The upper bound estimates significantly narrow the ranges of VG parameters,and the representative values of a and n for fractured rocks at the field scale can then be determined with confidence by inverse modeling using groundwater observations in saturated zones.The proposed methodology was applied to saturated-unsaturated flow modeling in the right-bank slope at the Baihetan dam site with a continuum approach,showing that most of the flow behaviors in fractured rocks in this complex hydrogeological condition could be properly reproduced.The proposed method overcomes difficulties in suction measurement in fractured rocks with strong heterogeneity,and provides a feasible way for modeling of saturated-unsaturated flow in fractured rocks with acceptable engineering accuracy.
基金Project(1301015A)supported by the Post-doctoral Research Fund of Jiangsu Province,ChinaProject Funded by the Priority Academic Program of Jiangsu Higher Education Institution,China+1 种基金Project(2014M561566)supported by China Postdoctoral Science FoundationProject(YK913007)supported by Key Laboratory of Earth-Rock Dam Failure Mechanism and Safety Control Technologies,China
文摘Two modifications for the basic Barcelona model(BBM) are present. One is the replacement of the net stress by the average skeleton stress in unsaturated soil modeling, and the other is the adoption of an expression for the load-collapse(LC) yield surface that can match flexibly the normal compression lines at different suctions. The predictions of the modified BBM for the controlled-suction triaxial test on the unsaturated compacted clay are presented and compared with the experimental results. A good agreement between the predicted and experimental results demonstrates the reasonability of the modified BBM. On this basis, the coupled processes of groundwater flow and soil deformation in a homogeneous soil slope under a long heavy rainfall are simulated with the proposed elasto-plastic model. The numerical results reveal that the failure of a slope under rainfall infiltration is due to both the reduction of soil suction and the significant rise in groundwater table. The evolution of the displacements is greatly related to the change of suction. The maximum collapse deformation happens near the surface of slope where infiltrated rainwater can quickly reach. The results may provide a helpful reference for hazard assessment and control of rainfall-induced landslides.
