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Role of equal-strain assumption in unit-cell theory for consolidation with vertical drains

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Journal of Central South University 2017年第12期24卷 2914-2923页

作者： LEI Guo-hui XU Li-dan ZHEng Qiang ng charles wang wai Key Laboratory of Geomechanics and Embankment Engineering of the Ministry of Education Geotechnical Research Institute Hohai University Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology

In the development of unit-cell theory for the analytical analysis of consolidation with vertical drains, the equal-strain assumption is often made with the intention of modelling consolidation under uniform settlement conditions. In contrast, the free-strain assumption for modelling consolidation under uniform load conditions is seldom employed, mainly because of the complexities involved in the analysis. This study derives a rigorous analytical solution to the generalised governing equations of free-strain consolidation with a vertical drain subjected to an instantaneous load. Calculated results from the newly proposed solution are compared with those from three available solutions derived based on the equal-strain assumption. Surprisingly good agreement is obtained in terms of excess pore-water pressure, degree of consolidation, and settlement. Horizontal profiles of settlement were not uniform before the end of consolidation. This indicates that the uniform settlement condition is not actually reproduced by the analytical solutions derived based on the equal-strain assumption. The equal-strain assumption is a sufficient but not necessary condition for deriving an analytical solution to unit-cell consolidation theory. The assumption plays no role in modelling consolidation under uniform settlement conditions but simplifies the analytical analysis of free-strain consolidation and results in an approximate solution of high accuracy for consolidation under uniform load conditions. Moreover, drain resistance and smear effects not only retard the consolidation rate, but also importantly shape the vertical and horizontal profiles of excess pore-water pressure, respectively.

关键词： consolidation ground improvement pore pressures settlement vertical drain

Three-dimensional numerical analysis of plant-soil hydraulic interactions on pore water pressure of vegetated slope under different rainfall patterns

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3696-3706页

作者： Haowen Guo charles wang wai ng Qi Zhang Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina

Understanding the pore water pressure distribution in unsaturated soil is crucial in predicting shallow landslides triggered by rainfall,mainly when dealing with different temporal patterns of rainfall ***,the hydrological response of vegetated slopes,especially three-dimensional(3D)slopes covered with shrubs,under different rainfall patterns remains unclear and requires further *** address this issue,this study adopts a novel 3D numerical model for simulating hydraulic interactions between the root system of the shrub and the surrounding *** series of numerical parametric studies are conducted to investigate the influences of slope inclination,rainfall pattern and rainfall *** rainfall patterns(advanced,bimodal,delayed,and uniform)and two rainfall durations(4-h intense and 168-h mild rainfall)are considered to study the hydrological response of the *** computed results show that 17%higher transpiration-induced suction is found for a steeper slope,which remains even after a short,intense rainfall with a 100-year return *** extreme rainfalls with advanced(PA),bimodal(PB)and uniform(PU)rainfall patterns need to be considered for the short rainfall duration(4 h),while the delayed(PD)and uniform(PU)rainfall patterns are highly recommended for long rainfall durations(168 h).The presence of plants can improve slope stability markedly under extreme rainfall with a short duration(4 h).For the long duration(168 h),the benefit of the plant in preserving pore-water pressure(PWP)and slope stability may not be sufficient.

关键词： Root-soil interactions Rainfall patterns Slope stability Three-dimensional(3D)

Three-year field study on grass growth and soil hydrological properties in biochar-amended soil

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2764-2774页

作者： Haowen Guo charles wang wai ng Junjun Ni Qi Zhang Yuchen wang Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina School of Transportation Southeast UniversityNanjingChina

Field monitoring was conducted to investigate and quantify the long-term effects of peanut shell biochar on soil-grass interaction over three *** 10 m5 m grassed plots were constructed in completely decomposed granitic *** of them were amended,respectively,with 5%and 10%biochar contents(m^(3)/m^(3))for grass growth,while the third was without biochar *** the threeyear monitoring,plant characteristics,saturated water permeability(k_(s))of grassed soil and soil suction were *** monitored results show that the grass leaf area index(LAI)and root length density(RLD)with biochar amendment were improved by 38%and 200%,*** the grassed plot without biochar,a threshold RLD existed with a value of 1.7 cm/cm^(3),beyond which k_(s) raised *** threshold RLD increased by 52%when biochar content increased from 0%to 10%.This implies that biochar may restrict the increase in k_(s) of grassed soil due to the rise in the threshold *** presence of biochar and grass can retain over 100%higher suction after heavy rainfalls,while 54%lower peak suction under evapotranspiration(ET)compared with the non-amended *** can alleviate the negative effects on hydraulic properties caused by plant growth and reduce ET-induced excessive water loss.A 5%peanut shell biochar content is recommended for the long-term management of vegetated earthen infrastructures.

关键词： Soil-grass interaction Biochar Long-term Water infiltration Soil drying

Modelling the water diversion of a sustainable cover system under humid climates

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2429-2440页

作者： Haowen Guo charles wang wai ng Qi Zhang Chuanxiang Qu Liwen Hu Shenzhen Research Institute of Hong Kong University of Science and Technology Shenzhen518057China Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong Kong SAR999077China CCCC Fourth Harbor Engineering Institute Co. LtdGuangzhou510230China

Extreme rainfall significantly threatens the safety of the landfill cover system,especially under humid *** study aims to provide design recommendations for a sustainable landfill cover system consisting of a low-permeability soil layer underlying a two-layer capillary barrier for humid ***,the numerical back-analysis was conducted for verification against a series of flume model ***,a parametric study was performed to investigate the effects of inclination angle,particle size and layer thickness on the lateral diversion length(DL)of the three-layer cover system under the 100-year return period rainfall of humid *** results show that the water lateral DL of the cover system can be greatly enhanced by increasing the inclination angle from 3°to 18°.Moreover,the bottom layer of the cover system with a coarser d10 was more susceptible to the impact of the heavy rainfall,while this can be alleviated by increasing the thickness of the bottom layer.A dimensionless number,defined as the ratio of thickness and d_(10) of the bottom layer,is proposed for designing lateral diversion of the three-layer cover system under humid *** preserve the maximum DL,it is suggested that the proposed dimensionless number should be larger than 95 and 110 for the design of rainfall events with 50-year and 100-year return periods for humid climates,respectively.

关键词： Unsaturated soil Recycling Construction waste Three-layer landfill cover Water infiltration

Is Terzaghi's effective stress a stress variable under seepage conditions?

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Journal of Central South University 2015年第6期22卷 2316-2321页

作者：雷国辉赵仲辉吴宏伟 Key Laboratory of Geomechanics and Embankment Engineering of Ministry of Education (Geotechnical Research Institute Hohai University) Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology

From the continuum mechanics perspective, an attempt was made to clarify the role of Terzaghi's effective stress in the theoretical analysis of saturated soil subjected to seepage. The necessity of performing a coupled hydromechanical analysis to solve the seepage-deformation interaction problem was illustrated by examining the equations of static equilibrium among the effective stress, seepage force, pore-water pressure and total stress. The conceptual definition of stress variable that satisfies the principles of continuum mechanics is applied in the coupled hydromechanical analysis. It is shown that Terzaghi's effective stress is in fact not a stress variable under seepage conditions, and the seepage force acting on the soil skeleton cannot be viewed as a body force. This offers a clue to the underlying cause of a paradox between the real Pascal's hydrostatic state and the hydrostatic state predicted by a class of continuum hydromechanical theories.

关键词： seepage-deformation interaction coupled hydromechanical analysis representative elementary volume stress variable stress state variable

Modulation doping of p-type Cu_(12)Sb_(4)S_(13)toward improving thermoelectric performance

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Journal of Materials Science & Technology 2024年第4期171卷 71-79页

作者： Khak Ho Lim Mingquan Li Yu Zhang Yue Wu Qimin Zhou Qingyue wang Xuan Yang Pingwei Liu Wen-Jun wang Ka wai Wong Ka Ming ng Yu Liu Andreu Cabot Institute of Zhejiang University-Quzhou Quzhou 324000China College of Chemical and Biological Engineering Zhejiang UniversityHangzhou 310007China School of Chemistry and Chemical Engineering Hefei University of TechnologyHefei 230009China Materials Research Institute The Pennsylvania State UniversityUniversity ParkPA 16802USA Ostia Technologies Limited United Kingdom Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayHong KongChina ICREA Pg.Lluis Companys 23Barcelona 08010Spain Catalonia Energy Research Institute-IREC Sant Adria del BesosBarcelona 08930Spain

The commercial viability of thermoelectric(TE)devices relies heavily on two factors:cost reduction and efficiency *** this study,we first produce p-type Cu_(12)Sb_(4)S_(16-x)(x=0,3,4)using a low-temperature bottom-up approach and demonstrate Cu_(12)Sb_(4)S_(13)to show the best TE performance among the three tested ***,the TE energy conversion efficiency of Cu_(12)Sb_(4)S_(13)is further enhanced by optimizing its electronic band structure through the incorporation of small amounts of *** an optimal Te content of 5 mol%,more than a twofold increase in the TE figure of merit(zT)is *** gain insight into the mechanism of improvement on the transport properties of the mate-rial,we compare the interphase transport mechanism by incorporating nanodomains of different metals(Ag and Cu)into the Cu_(12)Sb_(4)S_(13)*** improved electrical conductivity obtained with Cu_(12)Sb_(4)S_(13)-Te nanocomposites is attributed to a charge flooding of the Cu_(12)Sb_(4)S_(13)*** contrast,excessive down-ward band-bending at the interphases of Ag/Cu metal-semiconductor drastically reduces the electrical ***,a weighted mobility(μw)analysis shows a dominant thermal activation of carri-ers in Cu_(12)Sb_(4)S_(13)-Te *** this material,a strong decrease in lattice thermal conductivity is also found,which is associated with a phonon-carrier scattering *** work shows the impor-tance of proper band-engineering in TE nanocomposites to decouple electrical and thermal transport to enhance TE performance,and the efficacy ofμw for electrical and thermal transport analysis.

关键词： Modulation doping Thermoelectric Interphase transport Charge flooding Phonon-carrier scattering

Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation

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Neural Regeneration Research 2024年第5期19卷 1112-1118页

作者： Meng wang Shi-Qi Yao Yao Huang Jia-Jian Liang Yanxuan Xu Shaowan Chen Yuhang wang Tsz Kin ng wai Kit Chu Qi Cui Ling-Ping Cen Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong ShantouGuangdong ProvinceChina Shantou University Medical College ShantouGuangdong ProvinceChina Beijing Tongren Eye Center Beijing Tongren HospitalCapital Medical UniversityBeijingChina Department of Ophthalmology and Visual Sciences The Chinese University of Hong KongHong Kong Special Administrative RegionChina

Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible *** previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve *** investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal *** found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating *** analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 ***,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure *** data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation.

关键词： casein kinase-2 glaucoma intraocular pressure elevation macrophages retinal ganglion cells

植被生长对填埋场三层覆盖系统防渗性能的影响

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工程地质学报 2022年第5期30卷 1731-1743页

作者：郭浩文吴宏伟张琪陈锐张彦敏香港科技大学中国香港999077 哈尔滨工业大学(深圳) 深圳518055 深圳下坪环境园深圳518001

植物已被广泛用于改善岩土设施的服役性能。然而,植物生长对填埋场多层覆盖系统防渗性能的影响尚不清楚。本研究通过在深圳下坪固体废弃物填埋场开展为期两年的现场试验,并利用数值模拟进行对比与参数化分析,旨在量化湿润气候下植物生... 详细信息

植物已被广泛用于改善岩土设施的服役性能。然而,植物生长对填埋场多层覆盖系统防渗性能的影响尚不清楚。本研究通过在深圳下坪固体废弃物填埋场开展为期两年的现场试验,并利用数值模拟进行对比与参数化分析,旨在量化湿润气候下植物生长对土体水力性质以及三层覆盖系统防渗功能的影响。经研究发现,土体饱和渗透系数(k_(s))随根长密度(RLD)的增加呈线性下降。相比裸露土,植草土k_(s)、入渗量和入渗速率分别降低55%,18%和35%。这导致在现场监测期间植草覆盖系统中维持的吸力明显高于裸露覆盖系统,数值分析与实测结果相一致。然而,百年一遇降雨后两覆盖系统内吸力分布无显著差异。在两年的现场监测中,相比裸露覆盖系统,草类减少累积渗漏量达21%。通过裸露与植草覆盖系统的年均渗漏量均满足美国环保局建议的每年30 mm的设计要求,证明了没有土工膜的三层覆盖系统在湿润气候下的良好防渗性能。

关键词：三层填埋场覆盖系统现场试验植被非饱和土再生混凝土骨料无土工膜

Simultaneous determination of typical toxic aldehydes formed during food frying and digestion using isotope dilution UHPLC-QqQ-MS/MS

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Grain & Oil Science and Technology 2024年第1期7卷 42-49页

作者： Feng wang Yun Cui Dongjie Liu charles Brennan Soottawat Benjakul Weiwei Cheng Gengsheng Xiao Lukai Ma Key Laboratory of Green Processing and Intelligent Manufacturing of Lingnan Specialty Food of Ministry and Rural Affairs College of Light Industry and FoodZhongkai University of Agriculture and EngineeringGuangzhou 510225China School of Science Royal Melbourne Institute of Technology UniversityMelbourneAustralia International Center of Excellence in Seafood Science and Innovation Faculty of Agro-IndustryPrince of Songkla UniversitySongkhla 90110Thailand College of Food Science and Technology Zhejiang University of TechnologyHangzhou 310014China

An isotope dilution ultra-performance liquid chromatography-triple quadrupole mass spectrometry method was developed to simultaneously detect two typical kinds ofα,β-unsaturated aldehydes,namely 4-hydroxy-2-hexenal(4-HHE)and 4-hydroxy-2-nonenal(4-HNE),in *** proposed method exhibited a linear range of 10-1000 ng/mL with a limit of detection of 0.1-2.0 ng/g and a limit of quantification of 0.3-5.0 ng/*** recovery rates of these typical toxic aldehydes(i.e.,4-HHE,4-HNE)and their d3-labeled analogues were 91.54%-105.12%with a low matrix ***,this proposed method was successfully applied to a real frying system and a simulated digestion system,wherein the contents of 4-HHE and 4-HNE were determined for ***,the obtained results provide strong support for further research into the production of 4-HHE and 4-HNE resulting from foods during oil digestion and frying.

关键词： UHPLC-QqQ-MS/MS 4-Hydroxy-2-hexenal 4-Hydroxy-2-nonenal Frying Simulated digestion