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Engineering properties for high kitchen waste content municipal solid waste

Journal of Rock Mechanics and Geotechnical Engineering 2015年第6期7卷 646-658页

作者： Wu Gao Yunmin Chen Liangtong Zhan Xuecheng Bian MOE Key Laboratory of Soft soils and Geoenvironmental Engineering Institute of Civil EngineeringZhejiang University

Engineering properties of municipal solid waste （MSW） depend largely on the waste＇s initial compositionand degree of degradation. MSWs in developing countries usually have a high kitchen waste content（called HKWC MSW）. After comparing and analyzing the laboratory and field test results of physicalcomposition, hydraulic properties, gas generation and gas permeability, and mechanical properties forHKWC MSW and low kitchen waste content MSW （called LKWC MSW）, the following findings wereobtained：（1） HKWC MSW has a higher initial water content （IWC） than LKWC MSW, but the field capacitiesof decomposed HKWC and LKWC MSWs are similar; （2） the hydraulic conductivity and gaspermeability for HKWC MSW are both an order of magnitude smaller than those for LKWC MSW; （3）compared with LKWC MSW, HKWC MSW has a higher landfill gas （LFG） generation rate but a shorterduration and a lower potential capacity; （4） the primary compression feature for decomposed HKWCMSW is similar to that of decomposed LKWC MSW, but the compression induced by degradation ofHKWC MSW is greater than that of LKWC MSW; and （5） the shear strength of HKWC MSW changessignificantly with time and strain. Based on the differences of engineering properties between these twokinds of MSWs, the geo-environmental issues in HKWC MSW landfills were analyzed, including highleachate production, high leachate mounds, low LFG collection efficiency, large settlement and slopestability problem, and corresponding advice for the management and design of HKWC MSW landfills wasrecommended.

关键词： High kitchen waste content (HKWC) Municipal solid waste (MSW) Landfill Engineering properties Leachate MSW management

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Ground-borne vibrations due to dynamic loadings from moving trains in subway tunnels

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第11期13卷 870-876页

作者： Xue-cheng BIAN Wan-feng JIN Hong-guang JIANG Department of Civil Engineering MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310058 China

In this study,ground vibrations due to dynamic loadings from trains moving in subway tunnels were investigated using a 2.5D finite element model of an underground tunnel and surrounding soil *** our model,wave propagation in the infinitely extended ground is dealt with using a simple,yet efficient gradually damped artificial *** on the assumption of invariant geometry and material distribution in the tunnel's direction,the Fourier transform of the spatial dimension in this direction is applied to represent the waves in terms of the *** element discretization is employed in the cross-section perpendicular to the tunnel direction and the governing equations are solved for every discrete *** 3D ground responses are calculated from the wave-number expansion by employing the inverse Fourier *** accuracy of the proposed analysis method is verified by a semi-analytical solution of a rectangular load moving inside a soil stratum.A case study of subway train induced ground vibration is presented and the dependency of wave attenuation at the ground surface on the vibration frequency of the moving load is discussed.

关键词： Subway tunnel Moving train loadings Ground-borne vibration 2.5D finite element Gradually damped artificial boundary

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Effects of intense rainfall on stability of infinite terraced slope

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Journal of Central South University 2014年第4期21卷 1534-1545页

作者：马世国韩同春徐日庆吴渐张杰 Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University Key Laboratory of Soft soils and Geoenvironmental Engineering of Ministry of Education (Zhejiang University)

For fully understanding the hydrological dynamics of an infinite terraced slope, the infiltration process was studied by employing the Green and Ampt infiltration model. The limit equilibrium method and the Mohr-Coulomb failure criterion were adopted to derive a stability model for the infinite terraced slope subjected to an intense rainfall. Numerical simulation was performed for verifying its applicability. The results of numerical simulation indicate that a set of stepped wetting fronts are found during infiltration, and the infiltration of terraced slope covered by coarse-textured soils can be approximated as one-dimensional infiltration. The potential sliding surfaces from the numerical method are all parallel to the slope line, and the proposed model and framework can provide an approximate method of estimating how the infiltration affects the stability of an infinite terraced slope.

关键词： intense rainfall infiltration infinite terraced slope stability safety factor

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Experimental study on applicability of using time-domain reflectometry to detect NAPLs contaminated sands

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Science China(Technological Sciences) 2013年第8期56卷 1534-1543页

作者： ZHAN LiangTong MU QingYi CHEN YunMin CHEN RenPeng MOE Key Laboratory of Soft soils and Geoenvironmental Engineering Zhejiang University

Underground contamination by non-aqueous phase liquids (NAPLs) becomes increasingly serious. Rapid and reliable detection of contaminated zone and degree is the first step to site remediation. In this paper, diesel and fine sand are used as experiment materials to investigate the applicability of using time-domain reflectometry (TDR) to detect LNAPLs contamination. The major work includes: measurement of dielectric constant and electrical conductivity for the diesel-water-air-sand mixtures; measurement of reflection waveform and dielectric constant for specimens with a diesel contaminated layer being sandwiched in sand. The experimental results show the followings: A significant decrease in both dielectric constant and electrical conductivity is observed for the diesel-water-air-sand mixtures when diesel displaces the pore water, and the content of diesel can be calculated by the model; insignificant change in dielectric properties is measured when diesel only displaces the pore gas; when the diesel contaminated sand is sandwiched between two saturated sand layers, the interfaces of the diesel contaminated layer can be identified by analyzing the reflection waveform; for field application, TDR method is valid for the case that LNAPLs seep into saturated sand layer, and the applicability of TDR method in vadose zone depends on the initial saturation of the sand layer. The findings obtained in this paper provide a guidance for the use of TDR for the field investigation of NAPLs contaminated site.

关键词： LNAPLs sand time domain reflectometry dielectric constant electrical conductivity

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Elastic solutions for partially embedded single piles subjected to simultaneous axial and lateral loading

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Journal of Central South University 2014年第11期21卷 4330-4337页

作者：张磊龚晓南俞建霖 School of Civil Engineering Xi’an University of Architecture and Technology Key Laboratory of Soft soils and Geoenvironmental Engineering of Ministry of Education (Zhejiang University)

In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogeneous, semi-infinite isotropic medium. A comparison was made between model test results and the obtained solutions to show their validity. The calculation results indicate that the horizontal displacement and bending moment of the pile increase with increases of the axial and lateral loads. The maximum horizontal displacement and bending moment decrease by 37.9% and 13.9%, respectively, when the elastic modulus of soil increases from 4 MPa to 20 MPa. The Poisson ratio of soil plays a marginal role in pile responses. There is a critical pile length under the ground, beyond which the pile behaves as though it was infinitely long. The presented solutions can make allowance for the continuous nature of soil, and if condition permits, they can approach exact ones.

关键词： pile-soil interaction simultaneous axial and lateral loads difference method elastic modulus displacement

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Slope stability hazard management systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第11期8卷 1695-1711页

作者： FREDLUND Delwyn G. Department of Civil Engineering University of Saskatchewan Saskatoon SK Canada MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310027 China

Weather-related geo-hazards are a major concern for both natural slopes and man-made slopes and embankments. Government agencies and private companies are increasingly required to ensure that there is adequate protection of sloping sur- faces in order that interaction with the climate does not produce instability. Superior theoretical formulations and computer tools are now available to address engineering design issues related to the near ground surface soil-atmospheric interactions. An ex- ample is given in this paper that illustrates the consequences of not paying adequate attention to the hazards of slope stability prior to the construction of a highway in South America. On the other hand, examples are given from Hong Kong and China's Mainland where significant benefits are derived from putting in place a hazard slope stability management system. Some results from a hazard management slope stability study related to the railway system in Canada are also reported. The study took advantage of recent research on unsaturated soil behaviour and applied this information to real-time modelling of climatic conditions. The quantification of the water balance at the ground surface, and subsequent infiltration, is used as the primary tool for hazard level assessment. The suggested hazard model can be applied at either specific high risk locations or in a more general, broad-based manner over large areas. A more thorough understanding of unsaturated soil behaviour as it applies to near ground surface soils, along with the numerical computational power of the computer has made it possible for new approaches to be used in slope hazard management engineering.

关键词： Slope stability Geo-hazards Highway Hazard Slope stability management system

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Influence of lateral initial pressure on axisymmetric wave propagation in hollow cylinder based on first power hypo-elastic model

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Journal of Central South University 2014年第2期21卷 753-760页

作者：胡文韬夏唐代陈炜昀 Key Laboratory of Soft soils and Geoenvironmental Engineering of Ministry of Education (Zhejiang University) Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University

Influence of identical applied initial pressures on the radial surfaces of a hollow cylinder which is compose of materials with first power hypo-elastic constitutive model was *** basic equations of the problem were built up based on the framework of piecewise homogeneous body model with the use of three-dimensional linearized theory of elastic waves in initially stressed bodies(TLTEWISB).With the method proposed previously,this problem was then solved ***,the dispersion group velocity of the lowest order mode with different initial pressures was also *** can be concluded that the initial pressure and the geometry parameters will induce considerable changes of different degrees in dispersive relation between phase velocity and wave number in opposite trend(positive in initial pressure and negative in thickness).

关键词： initial pressure TLTEWISB first power hypo-elastic model dispersive relation

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Excavation collapse of Hangzhou subway station in soft clay and numerical investigation based on orthogonal experiment method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第10期13卷 760-767页

作者： Xiao-nan GONG Xue-chan ZHANG MOE Key Laboratory of Soft soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310058China Institute of Geotechnical Engineering Zhejiang UniversityHangzhou 310058China

This paper studies the excavation collapse at the Xianghu subway station on Hangzhou metro line *** objective is to present an overview of this case study and discuss the cause of the *** field investigation and preliminary analysis,the reasons for the excavation collapse were the misuse of the soil parameters,over excavation,incorrect installation of steel struts,invalid monitoring data,and inadequate ground ***,a small strain constitutive model was used for further *** order to estimate damage efficiently,the orthogonal array(OA) was introduced for screening the key factor in the numerical *** estimated indexes including deformations and internal forces of the excavation were taken,and the effectiveness of four factors which may cause the collapse was *** numerical experiments and interaction analysis,it is found that the deformation and internal force can be well controlled by jet grouting of the subsoil under the final cutting surface,but increasing the improvement ratio of the jet grouting cannot help optimize the excavation behavior efficiently,and without jet grouting and the fourth level struts,the deformation and internal force of the excavation in this case will far surpass the allowable value.

关键词： Collapse Case study Numerical analysis Orthogonal experiment method Interaction

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Analysis of 1D consolidation with non-Darcian flow described by exponent and threshold gradient

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第9期11卷 656-667页

作者： Chuan-xun LI Kang-he XIE Kun WANG MOE Key Laboratory of Soft soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310027 China Department of Civil Engineering Jiangsu University Zhenjiang 212013 China

Numerous experiments have shown that the water flow in fine-grained soils can obey an exponential relationship at small gradients and a linear relationship when the hydraulic gradient exceeds a certain limit. Based on the non-Darcian flow described by exponent and threshold gradient, the theory of 1D consolidation is modified in this paper to consider a linear variation in the vertical total stress with depth and the effect of ramp loading. The numerical solutions were derived in detail by the finite difference method for excess pore water pressure and the average degree of consolidation. Finally, the influence of various parameters on consolidation behavior was investigated. The results show that the rate of consolidation is reduced when non-Darcian flow described by exponent and threshold gradient is adopted in the theory of 1D consolidation. As well the distribution of vertical total stress has a great influence on the dissipation of excess pore water pressure, either for pervious top and pervious bottom (PTPB) or for pervious top and impervious bottom (PTIB). For the case of PTIB, the distribution of vertical total stress in a foundation has a great influence on the rate of consolidation; however, for the case of PTPB, the rate of consolidation is independent of the distribution of vertical total stress. The rate of consolidation is dependent on the ratio of the thickness of a soil layer to the equivalent head of the final average vertical total stress; the greater the value of this ratio, the slower the rate of consolidation. Finally, an increase in construction time reduces the consolidation rate of a foundation. Thus, consolidation behavior of 1D consolidation with non-Darcian flow has been thoroughly acquainted in this paper.

关键词： 1D consolidation Non-Darcian flow Ramp loading Non-uniform distribution of vertical total stress

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A comprehensive approach for assessing the economic contribution of forage and livestock improvement options to smallholder farming enterprises

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Journal of Integrative Agriculture 2015年第8期14卷 1573-1580页

作者： Neil Mac Leod Scott Waldron WEN Shi-lin Agriculture Flagship Commonwealth Scientific and Industrial Research Organisation (CSIRO) University of Queensland Red soils Experimental Station Chinese Academy of Agricultural Sciences

The importance of livestock production activities to improving the livelihoods of smallholder farming households and the efficiency of their underlying farming systems is increasingly recognized.A rapid increase in livestock numbers, especially beef cattle, and special purpose forages is being promoted for smallholder farms which have traditionally undertaken subsistence cropping activities or simple livestock rearing activities using low quality *** limited plantings of specialized forages combined with a poor knowledge of animal nutrition are a challenge to establishing sustainable livestock enterprises, much public policy and research is now being focused on the use of new forages and improved feeding practices.A number of economic studies have suggested that specialized forage growing and livestock feeding activities can make a positive contribution to smallholder *** studies have typically compared the total level of farm or household income with and without livestock *** attention is given to how much the new forage or livestock activities actually contribute to or draw resources from other farm activities to assess their real economic contribution to the enterprise, and the availability of simple tools to assist in making such assessments are *** paper describes a simple modelling approach that was developed for an Australian Centre for International Agricultural Research（ACIAR）-supported project to explore the real as opposed to apparent economic impact of integrating improved forages and livestock within smallholder farming systems in the Red soils region of south-central *** of the model is demonstrated using a simple case study of a smallholder enterprise that plans to introduce a new beef cattle rearing activity to its existing farm activity *** case study highlights the importance of explicitly valuing transfers of resources between different farm activities to gauge the real contribution o

关键词： smallholder farming systems economics resource transfers opportunity costs economic profit

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