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Effect of freeze-thaw cycles on soil engineering properties of reservoir bank slopes at the northern foot of Tianshan Mountain

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Journal of Mountain Science 2021年第2期18卷 541-557页

作者： QIN Zi-peng LAI Yuan-ming TIAN Yan ZHANG Ming-yi State Key Laboratory of Frozen soil engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China College of Civil engineering and Mechanics Lanzhou UniversityLanzhou 730000China

The instability of soil bank slopes induced by freeze-thaw cycles at the northern foot of Tianshan Mountain is very *** failure not only caused a large amount of soil erosion,but also led to serious reservoir sedimentation and water quality degradation,which exerted a lot of adverse effects on agricultural production in the local irrigation *** on field investigations on dozens of irrigation reservoirs there,laboratory tests were carried out to quantitatively analyze the freeze-thaw effect on the soil engineering characteristics to reveal the facilitation on the bank slope *** results show that the softening characteristics of the stressstrain curves gradually weaken,the effective cohesions decline exponentially,the seepage coefficients enlarge,and the thermal conductivities decrease after 7 freeze-thaw *** freeze-thaw effect on the specimens with low confining pressures,low dry densities and high water contents is more *** water migration and the phase transition between water and ice result in the variations of the soil internal microstructures,which is the main factor affecting the soil engineering *** water supply and the alternation of positive and negative temperatures at the reservoir bank slopes in cold regions make the water migration and phase transition in the soil very *** is easy to form a large number of pores and micro cracks in the soil freezing and thawing *** volume changes of the soil and the water migration are difficult to reach a dynamic balance in the open ***-term freeze-thaw cycles will bring out the fragmentation of the soil particles,resulting in that the micro cracks on the soil surfaces are developing *** soil of the bank slopes will fall or collapse when these cracks penetrate,which often happens in winter there.

关键词： Mechanical properties Seepage coefficient Thermal conductivity Micro structure Freeze-thaw cycles Reservoir bank slope

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Comparative analysis on soil engineering classifications of China and America

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Global Geology 2012年第3期15卷 210-215页

作者： CHEN Huie SHI Mingyuan GUO Zhen College of Construction engineering Jilin University Changchun 130026 China Department of Geology and Geological engineering University of Mississippi MS 38677 USA

Based on China National Standard of soil engineering Classification (GB/T 50145-2007) and the Unified soil Classification System of American Society for Testing Materials (ASTM D-2478), two kinds of soil laboratory engineering classification methods were discussed and analyzed from the aspects of the definition in particle fraction, classification of soil type and evaluation standard for soil gradation. There is a same limit of fine grains fraction in the two standards, and there are three main types of soil in GB/T 50145-2007 and two in ASTM D-2487. Different evaluation standards of gradation are put forward for gravels and sands in ASTM D-2487. Same criteria of A line, B line and controlling value of plastic index are in the plasticity chart of both standards.

关键词： GB/T 50145-2007 ASTM D-2487 soil engineering classification particle fraction gradation plasticity chart

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Installation of a Riparian Forest by Means of soil Bio engineering Techniques—Monitoring Results from a River Restoration Work in Southern Brazil

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Open Journal of Forestry 2014年第2期4卷 161-169页

作者： Hans Peter Rauch Fabricio Sutili Stephan Horbinger Department for Civil engineering and Natural Hazards University of Natural Resources and Life SciencesInstitute of Soil Bioengineering and Landscape ConstructionViennaAustria Departamento de Ciencias Florestais Universidade Federal de Santa MariaSanta MariaBrazil

soil bioengineering has been applied more and more in different regions of Brazil in recent years. The study in hand presents the installation of “new” riparian forest based on soil bioengineering techniques. This riverbank restoration work was implemented in the year 2010 and two onsite vegetation surveys, one shortly after the construction, and one in 2013. Besides that, the structures of reinforcement work, and its effectiveness were evaluated. By means of the vegetation survey, the applied species were examined for their ability to establish the riverbank in an environmentally sustainable way. Most notably, the species Calliandra brevipes Benth. (Fabaceae, Mimosoideae), Phyllanthus sellowianus Müller Arg. (Euphorbiaceae), Salix humboldtiana Willd. (Salicaceae), Bauhinia forficate Link (Leguminosae), Inga marginata Willd. (Mimosoideae) and Ateleia glazioveana Baill. (Leguminosae, Papilionoideae) showed a good growth development. The proportion of spontaneous vegetation increased significantly, with Pennisetum purpureum Schumach. becoming a dominating species. Resulting from that, the intervention can be assessed as functional and safe, but the strong increase of spontaneous vegetation is undesirable due to less flood resistance. The vegetated riprap could be the best to meet the expectations of the construction elements. Partly, the anchored willows showed as well a good growth development whereas the species used for the hedge brush layer could not develop as expected in large parts of the construction.

关键词： soil Bioengineering Riverbank Restoration Riparian Forest Rio Grande do Sul

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Impact of soil compaction on the engineering properties of potato tubers

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International Journal of Agricultural and Biological engineering 2020年第2期13卷 163-167页

作者： Mohamed K.Edrris Khalid A.Al-Gaadi Abdalhaleem A.Hassaballa ElKamil Tola Khalid A.M.Ahmed Precision Agriculture Research Chair King Saud UniversityRiyadh 11451Saudi Arabia Department of Agricultural engineering College of Food and Agriculture SciencesKing Saud UniversityRiyadh 11451Saudi Arabia Department of Agricultural&Biological engineering Faculty of EngineeringKhartoum UniversityKhartoumSudan Chair of Dates Industry and Technology King Saud UniversityRiyadh 11451Saudi Arabia

A study on a 30 hm2 field was conducted to assess the variability in soil compaction and to investigate its effect on the engineering properties of potato tubers in terms of tuber shape and key dimensions(length,width and thickness)and resistance to penetration,rupture and shear *** soil compaction levels were spatially correlated with the engineering properties of potato tubers through linear regression and ANOVA *** three compaction levels included a low level(C1)ranging between 1.2-1.9 MPa,a medium level(C2)with compaction levels between 2.0-2.3 MPa and a high level(C3)ranging between 2.4-2.9 *** revealed that there were no significant changes in the key tuber dimensions corresponding to the variability in soil ***,inverse linear relationships were observed between soil compaction and the key tuber dimensions with R2 values of 77%,97%and 96%for length,width and thickness,***,the soil compaction was shown to have no effect on the tuber resistance to compression and shear *** contrast,the tuber resistance to penetration was significantly affected by soil compaction(p>F=0.0012).

关键词： compaction potato tubers precision agriculture potato engineering properties

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Experimental Study on engineering Behavior of Solidified soil for Scour Repair and Protection

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China Ocean engineering 2024年第4期38卷 625-635页

作者： WU Xiao-ni LI Ru-yu SHU Jian TANG Chao CHEN Jin-jian WANG Hui-li JIANG Hai-li WANG Xiao State Key Laboratory of Ocean engineering Department of Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Road and Bridge Group Co. Ltd.Shanghai 200433China Shanghai engineering Research Center of Urban Infrastructure Renewal Shanghai 200032China Jiangsu Kunze Technology Co. Ltd.Nanjing 210000China

A new scour countermeasure using solidified slurry for offshore foundation has been proposed *** solidified slurry is pumped to seabed area around foundation for scour protection or pumped into the developed scour holes for scour repair as the fluidized material solidifies *** the pumping operation and solidification,the engineering behaviors of solidified slurry require to be considered synthetically for the reliable application in scour repair and protection of ocean engineering such as the pumpability related flow value,flow diffusion behavior related rheological property,anti-scour performance related retention rate in solidification and bearing capacity related strength property after *** this study,a series of laboratory tests are conducted to investigate the effects of mix proportion(initial water content and binder content)on the flow value,rheological properties,density,retention rate of solidified slurry and unconfined compressive strength(UCS).The results reveal that the flow value increases with the water content and decreases with the binder *** the solidified slurry exhibits Bingham plastic behavior when the shear rate is larger than 5 s^(-1).The Bingham model has been employed to fit the rheology test results,and empirical formulas for obtaining the density,yield stress and viscosity are established,providing scientific support for the numerical assessment of flow and diffusion of solidified *** rate of solidified slurry decreases with the water flow velocity and flow value,which means the pumpability of solidified slurry is contrary to anti-scour *** unconfined compressive strength after solidification reduces as the water content increases and binder content decreases.A design and application procedure of solidified soil for scour repair and protection is also proposed for engineering reference.

关键词： scour repair and protection solidified soil pumpability strength flow properties anti-scour performance

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Thermal and hydrological processes in permafrost slope wetlands affect thermosyphon embankment stability

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Advances in Climate Change Research 2024年第4期15卷 680-694页

作者： Bo-Wen TAI Qing-Bai WU Xiao-Ming XU State Key Laboratory of Frozen soil engineering Key Laboratory of Cryospheric Science and Frozen Soil EngineeringNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China School of engineering Science University of Chinese Academy of SciencesBeijing 100049China

To ensure the long-term service performance of infrastructure such as railways,highways,airports and oil pipelines built on permafrost slope wetland sites,it is imperative to systematically uncover the long-term heat-water changes of soil in slope wetlands environment under climate *** specifically,considering valuable field data from 2001 to 2019,the long-term heat and water changes in active layers of the slope wetland site along the Qinghai-Xizang Railway(QXR)are illustrated,the effect of thermosyphon measures in protecting the permafrost environment is evaluated,and the influences of climate warming and hydrological effects on the stability of slope wetland embankments are systematically *** permafrost at the slope wetland site is rapidly degrading,demonstrating a reduction in active layer thickness of>3.7 cm per year and a permafrost temperature warming of>0.006℃ per *** thermosiphon embankment developed by QXR has a specific cooling period;thus,to mitigate the long-term impacts of climate warming on the thermal stability of permafrost foundation,it is essential to implement strengthening measures for the thermosiphon embankment,such as adding a crushed-rock layer or sunshade board on the slope of thermosiphon embankment to creating a composite cooling ***-term seasonal groundwater seepage intensifies frost damage to the slope wetland embankment,while long-term seasonal supra-permafrost water and groundwater seepage exacerbates uneven transverse deformation of slope wetland ***-term climate warming and slope effects have altered the surface water and groundwater hydrological processes of slope wetlands,potentially leading to an increased occurrence of slope embankment *** results are crucial for improving our understanding of heat and water variation processes in the active layer of slope wetland sites located in permafrost regions and ensuring long-term service safety for the QXR.

关键词： Heat and water process Active layer Slope wetland Permafrost environment Thermosyphon embankment

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Promotion effects of salt-alkali on ammonia volatilization in a coastal soil

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Pedosphere 2024年第1期34卷 191-199页

作者： Zhenqi SHI Dongli SHE Yongchun PAN Yongqiu XIA College of Agricultural Science and engineering Hohai UniversityNanjing 210098China Jiangsu Province engineering Research Center for Agricultural soil-Water Efficient Utilization Carbon Sequestration and Emission ReductionNanjing 210098China Key Laboratory of soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

Coastal ecosystems are highly susceptible to salt-related problems due to their formation process and geographical location. As such ecosystems are the most accessible land resources on Earth, clarifying and quantifying the effects of salt-alkali conditions on N concentration and ammonia(NH_(3)) volatilization are pivotal for promoting coastal agricultural productivity. The challenge in establishing this effect is to determine how salt-alkali conditions impact NH_(3) volatilization through direct or indirect interactions. An incubation experiment using a coastal soil from a paddy farmland, combined with the structural equation modeling(SEM) method, was conducted to reveal the net effects of salt-alkali on NH_(3) volatilization and the role of environmental and microbial factors in mutual interaction networks. The specific experimental design consisted of four salt treatments(S1, S2, S3, and S4: 1‰, 3‰, 8‰, and 15‰ NaCl by mass of soil, respectively), four alkaline treatments(A1, A2, A3, and A4: 0.5‰, 1‰, 3‰, and 8‰ NaHCO_(3)by mass of soil, respectively) and a control without NaCl or NaHCO_(3) addition(CK), and each treatment had three urea concentrations(N1, N2, and N3: 0.05, 0.10, and 0.15 g N kg^(-1) soil,respectively) and three replicates. At the N1, N2, and N3 levels, NH_(3)volatilization increased by 9.31%–34.98%, 3.07%–26.92%, and 2.99%–43.61% as the NaCl concentration increased from 1‰ to 15‰, respectively, compared with CK. With an increase in the NaHCO_(3)concentration from 0.5‰ to 8‰, NH_(3) volatilization increased by 8.36%–56.46%, 5.49%–30.10%, and 30.72%–73.18% at the N1, N2, and N3 levels, respectively, compared with CK. According to the SEM method, salinity and alkalinity had positive direct effects on NH_(3)volatilization, with standardized path coefficients of 0.40 and 0.19, *** the total effects(net positive and negative effects) in the SEM results, alkalinity had a greater influence than salinity(total standardized coefficien

关键词： alkalinity coastal ecosystem NH_(3)emission N-transforming microbe salinity structural equation modeling

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Tensile strength behavior of cement-stabilized dredged sediment reinforced by polypropylene fiber

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Frontiers of Structural and Civil engineering 2024年第3期18卷 380-392页

作者： Lei LANG Jiangshan LI Xin CHEN Lijun HAN Ping WANG State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicChinese Academy of SciencesWuhan 430071China Hubei Provincial Key Laboratory of Contaminated Sludge and soil Science and engineering Wuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

This study evaluated the feasibility of using polypropylene fiber(PF)as reinforcement in improving tensile strength behavior of cement-stabilized dredged sediment(CDS).The effects of cement content,water content,PF content and length on the tensile strength and stress–strain behavioral evolutions were evaluated by conducting splitting tensile strength ***,the micro-mechanisms characterizing the tensile strength behavior inside PF-reinforced CDS(CPFDS)were clarified via analyzing macro failure and microstructure *** results indicate that the highest tensile strengths of 7,28,60,and 90 d CPFDS were reached at PF contents of 0.6%,1.0%,1.0%,and 1.0%,exhibiting values 5.96%,65.16%,34.10%,and 35.83%higher than those of CDS,***,3 mm,PF of showed the best reinforcement *** CPFDS exhibited obvious tensile strain-hardening characteristic,and also had better ductility than *** mix factor(C_(C)^(a)/C_(w)^(b))and time parameter(q_(t0)(t))of CDS,and the reinforcement index(k_(t-PF))of CPFDS were used to establish the tensile strength prediction models of CDS and CPFDS,considering multiple *** PF“bridge effect”and associated cementation-reinforcement coupling actions inside CPFDS were mainly responsible for tensile strength behavior *** key findings contribute to the use of CPFDS as recycled engineering soils.

关键词： dredged sediment chemical stabilization fiber reinforcement splitting tensile strength micro-mechanisms

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Co-incorporation of Chinese milk vetch(Astragalus sinicus L.)and chemical fertilizers alters microbial functional genes supporting short-time scale positive nitrogen priming effects in paddy soils

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Pedosphere 2024年第3期34卷 567-576页

作者： Limin WANG Chunmei HE Dongfeng HUANG Juhua YU Cailing LIU Qinghua LI Yibin HUANG Juan LI Fei WANG Institute of Resources Environment and Soil FertilizerSoil and Fertilizer InstituteFujian Academy of Agricultural SciencesFuzhou 350012(China) School of Resources and Environment engineering Anhui UniversityHefei 230601(China)

Nitrogen(N)priming is a microbially mediated biochemical process as affected by different incorporation ***,little information is known about the microbial mechanisms driving the response of N priming to co-operation of Chinese milk vetch(CMV,Astragalus sinicus L.)and different rates of chemical fertilizers in paddy soils in South ***,an anaerobic incubation experiment was conducted to study N priming effects(PE)and their relationships with soil microbial functional genes after CMV incorporation alone(M),co-incorporation of CMV with 100%(normal dosage)chemical fertilizers(MC100),and co-incorporation of CMV with 80% chemical fertilizers(MC80).Co-incorporation of CMV and chemical fertilizers enhanced the short-time scale(the first 20 d of incubation)positive PE of N,while no significant differences existed among the three treatments on day 60 or 90 of incubation(P>0.05).Compared with the M treatment,gross priming effect(GPE)in the MC100 and MC80 treatments significantly increased by 34.0% and 31.3%,respectively,and net priming effect(NPE)increased by 47.7% and 47.8%,respectively,during the first 20 d of incubation(Psoil nutrient availability and added substrate *** MC100 and MC80 treatments increased the gdhA gene abundance by 5.0% and 9.8%,increased the gdh2 gene abundance by 12.7% and 45.7%,and increased the nasB gene abundance by 9.5% and 41.4%,respectively,in comparison with the M treatment on day 20 of *** analyses indicated that soil microbial functional genes involved in N mineralization(gdhA and gdh2),assimilatory nitrate reduction(nasB),and nitrification(amoB)were significantly correlated with N priming under different incorporation practices during the incubation period(Psoil microbial community functional gene structure,which may accelerate mineralization and assimilatory nitrate reduction and inhibit

关键词： green manure gross priming effect incorporation practice microbial mechanism net priming effect rice field soil

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Coupling effect of cement-stabilization and biopolymer-modification on the mechanical behavior of dredged sediment

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Journal of Rock Mechanics and Geotechnical engineering 2024年第8期16卷 3284-3298页

作者： Lei Lang Jiangshan Li Xiao Huang Ping Wang Wei Zhang State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Hubei Provincial Key Laboratory of Contaminated Sludge and soil Science and engineering Wuhan430071China University of Chinese Academy of Sciences Beijing100049China

Nowadays,biopolymer stabilization as a promising eco-friendly approach in soft ground improvement has attracted wide ***,the feasibility of using biopolymer as a green additive of cementstabilized dredged sediment(CDS)with high water content is still *** this study,guar gum(GG)and xanthan gum(XG)were adopted as typical biopolymers,and a series of unconfined compressive strength(UCS),splitting tensile strength(STS)and scanning electron microscopy(SEM)tests were performed to evaluate the mechanical and microstructural properties of XG-and GG-modified CDSs considering several factors including biopolymer modification,binderesoil ratio and wateresolid ***,the micro-mechanisms revealing the evolutions of mechanical properties of biopolymermodified CDS were *** results indicate that the addition of XG can effectively improve the strength of CDS,while the GG has a side *** XG content of 9%was recommended,which can improve the 7 d-and 28 d-UCSs by 196%and 51.8%,together with the 7 d-and 28 d-STSs by 118.3%and 42.2%,*** the binderesoil ratio or decreasing the wateresolid ratio significantly improved the strength gaining but aggravated the brittleness characteristics of *** XG to CDS contributed to the formation of microstructure with more compactness and higher cementation degrees of ordinary Portland cement(OPC)-XG-stabilized DS(CXDS).The micro-mechanism models revealing the interactions of multiple media including OPC cementation,biopolymer film bonding and bridging effects inside CXDS were *** key findings confirm the feasibility of XG modification as a green and high-efficiency mean for improving the mechanical properties of CDS.

关键词： Dredged sediment(DS) Stabilization Biopolymer modification Mechanical properties Micro-mechanism

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