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Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents 被引量:1
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作者 Xiaobin Zhang Aoqi Wang +1 位作者 Xingbao Wang Wenying Li 《International Journal of Coal Science & Technology》 EI CAS CSCD 2024年第2期187-197,共11页
The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction.Thus,a theoretical basis for process optimiz... The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction.Thus,a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents.Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions.In this study,the composition and content of liquefied solvents were analyzed.As model compounds,hexadecane,toluene,naphthalene,tetrahydronaphthalene,and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic,bicyclic,and tricyclic aromatic hydrocarbons.The solubility of hydrogen X(mol/mol)in pure solvent components and mixed solvents(alkanes and aromatics mixed in proportion to the chain alkanes+bicyclic aromatic hydrocarbons,bicyclic saturated aromatic hydrocarbons+bicyclic aromatic hydrocarbons,and bicyclic aromatic hydrocarbons+compounds containing het-eroatoms composed of mixed components)are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa.The results demonstrated that at high temperatures and pressures,the solubility of hydrogen in the solvent increases with the increase in temperature and pressure,with the pressure having a greater impact.Further-more,the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents,and the solubility of eicosanoids reaches a maximum of 0.296.The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number.The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons.The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents.Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms. 展开更多
关键词 Direct coal liquefaction liquefaction solvents Process simulation Hydrogen solubility
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Numerical and experimental study on the falling film flow characteristics with the effect of co-current gas flow in hydrogen liquefaction process 被引量:1
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作者 Chong-Zheng Sun Yu-Xing Li +2 位作者 Hui Han Xiao-Yi Geng Xiao Lu 《Petroleum Science》 SCIE EI CAS CSCD 2024年第2期1369-1384,共16页
Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy. Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat ... Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy. Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat exchanger structure and hydrogen liquefaction process(LH2). The methods of cryogenic visualization experiment, theoretical analysis and numerical simulation are conducted to study the falling film flow characteristics with the effect of co-current gas flow in LH2spiral wound heat exchanger.The results show that the flow rate of mixed refrigerant has a great influence on liquid film spreading process, falling film flow pattern and heat transfer performance. The liquid film of LH2mixed refrigerant with column flow pattern can not uniformly and completely cover the tube wall surface. As liquid flow rate increases, the falling film flow pattern evolves into sheet-column flow and sheet flow, and liquid film completely covers the surface of tube wall. With the increase of shear effect of gas-phase mixed refrigerant in the same direction, the liquid film gradually becomes unstable, and the flow pattern eventually evolves into a mist flow. 展开更多
关键词 Hydrogen liquefaction Spiral wound heat exchanger Flow pattern transition Falling film flow
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Liquefaction susceptibility and deformation characteristics of saturated coral sandy soils subjected to cyclic loadings-a critical review 被引量:1
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作者 Chen Guoxing Qin You +3 位作者 Ma Weijia Liang Ke Wu Qi C.Hsein Juang 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第1期261-296,共36页
Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions.Due to the unique marine depositional environment of coral sandy soils,the engineering characteristics and respons... Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions.Due to the unique marine depositional environment of coral sandy soils,the engineering characteristics and responses of these soils subjected to monotonic and cyclic loadings have been a subject of intense interest among the geotechnical and earthquake engineering communities.This paper critically reviews the progress of experimental investigations on the undrained behavior of coral sandy soils under monotonic and cyclic loadings over the last three decades.The focus of coverage includes the contractive-dilative behavior,the pattern of excess pore-water pressure(EPWP)generation and the liquefaction mechanism and liquefaction resistance,the small-strain shear modulus and strain-dependent shear modulus and damping,the cyclic softening feature,and the anisotropic characteristics of undrained responses of saturated coral sandy soils.In particular,the advances made in the past decades are reviewed from the following aspects:(1)the characterization of factors that impact the mechanism and patterns of EPWP build-up;(2)the identification of liquefaction triggering in terms of the apparent viscosity and the average flow coefficient;(3)the establishment of the invariable form of strain-based,stress-based,or energy-based EPWP ratio formulas and the unique relationship between the new proxy of liquefaction resistance and the number of cycles required to reach liquefaction;(4)the establishment of the invariable form of the predictive formulas of small strain modulus and strain-dependent shear modulus;and(5)the investigation on the effects of stress-induced anisotropy on liquefaction susceptibility and dynamic deformation characteristics.Insights gained through the critical review of these advances in the past decades offer a perspective for future research to further resolve the fundamental issues concerning the liquefaction mechanism and responses of coral sandy sites subjected to cyclic loadings associated with seismic events in marine environments. 展开更多
关键词 liquefaction susceptibility dynamic deformation characteristics coral sandy soil cyclic loading review and prospect
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Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction
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作者 WANG Zhao-jun SUI Ti-ti +1 位作者 ZHANG Chi PAN Jun-ning 《China Ocean Engineering》 SCIE EI CSCD 2024年第1期93-103,共11页
The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal engineers.In this study,an analytical formula considering the nonlin... The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal engineers.In this study,an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed surface.The liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed liquefaction.Based on the 2D full dynamic model of wave-induced seabed response,a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed liquefaction.Further,new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear wave.Results indicate that(1)Due to the influence of wave nonlinearity,the vertical transmission of negative pore water pressure in the seabed is hindered,and therefore,the amplitude decreases significantly.(2)In general,with the increase of wave nonlinearity,the liquefaction depth of seabed decreases gradually.Especially under asymmetric and skewed wave loading,the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave conditions.However,highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave.(3)The asymmetry of wave pressure leads to the increase of liquefaction width,whereas the influence of skewedness is not significant.(4)Compared with the nonlinear waveform,seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading. 展开更多
关键词 nonlinear wave seabed response seabed liquefaction numerical simulation liquefaction prediction
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The Analysis of the Correlation between SPT and CPT Based on CNN-GA and Liquefaction Discrimination Research
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作者 Ruihan Bai Feng Shen +2 位作者 Zihao Zhao Zhiping Zhang Qisi Yu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期1159-1182,共24页
The objective of this study is to investigate themethods for soil liquefaction discrimination. Typically, predicting soilliquefaction potential involves conducting the standard penetration test (SPT), which requires f... The objective of this study is to investigate themethods for soil liquefaction discrimination. Typically, predicting soilliquefaction potential involves conducting the standard penetration test (SPT), which requires field testing and canbe time-consuming and labor-intensive. In contrast, the cone penetration test (CPT) provides a more convenientmethod and offers detailed and continuous information about soil layers. In this study, the feature matrix based onCPT data is proposed to predict the standard penetration test blow count N. The featurematrix comprises the CPTcharacteristic parameters at specific depths, such as tip resistance qc, sleeve resistance f s, and depth H. To fuse thefeatures on the matrix, the convolutional neural network (CNN) is employed for feature extraction. Additionally,Genetic Algorithm (GA) is utilized to obtain the best combination of convolutional kernels and the number ofneurons. The study evaluated the robustness of the proposed model using multiple engineering field data sets.Results demonstrated that the proposed model outperformed conventional methods in predicting N values forvarious soil categories, including sandy silt, silty sand, and clayey silt. Finally, the proposed model was employedfor liquefaction discrimination. The liquefaction discrimination based on the predicted N values was comparedwith the measured N values, and the results showed that the discrimination results were in 75% agreement. Thestudy has important practical application value for foundation liquefaction engineering. Also, the novel methodadopted in this research provides new ideas and methods for research in related fields, which is of great academicsignificance. 展开更多
关键词 CNN liquefaction discrimination SPT CPT
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Mechanisms to explain soil liquefaction triggering,development,and persistence during an earthquake
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作者 Fernando Teixeira 《Earthquake Science》 2024年第6期558-573,共16页
Mechanisms have been proposed to explain the triggering,development,and persistence of soil liquefaction.The mechanism explaining the horizontal failure plane(triggering)and its depth below the phreatic surface is gov... Mechanisms have been proposed to explain the triggering,development,and persistence of soil liquefaction.The mechanism explaining the horizontal failure plane(triggering)and its depth below the phreatic surface is governed by the flux properties and effective stress at that plane.At the failure plane,the pore water pressure was higher than the effective stress,and the volume change was the highest.The pore water pressure is a function of the soil profile features(particularly the phreatic zone width)and bedrock motion(horizontal acceleration).The volume change at the failure plane is a function of the intrinsic permeability of the soil and bedrock displacement.The failure plane was predicted to occur during the oscillation with the highest amplitude,disregarding further bedrock motion,which was consistent with low seismic energy densities.Two mechanisms were proposed to explain the persistence of soil liquefaction.The first is the existence of low-permeability layers in the depth range in which the failure planes are predicted to occur.The other allows for the persistence and development of soil liquefaction;it is consistent with homogeneous soils and requires water inflow from bedrock water springs.The latter explains many of the features of soil liquefaction observed during earthquakes,namely,surficial effects,“instant”liquefaction,and the occurrence of short-and long-term changes in the level of the phreatic surfaces.This model(hypothesis),the relationship between the flux characteristics and loss of soil shear strength,provides self-consistent constraints on the depth below the phreatic surfaces where the failure planes are observed(expected to occur).It requires further experimental and observational evidence.Similar reasoning can be used to explain other saturated soil phenomena. 展开更多
关键词 soil liquefaction triggering soil liquefaction persistence intrinsic soil permeability impervious soil layers bedrock water springs
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Liquefaction and post-liquefaction behaviors of sands affected by immersion-induced degradation of crushed mudstone
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作者 Tadao Enomoto 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第5期1799-1812,共14页
A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing b... A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing behavior without precedent cyclic-loading histories of sands containing crushed mudstone.The tested materials with a main particle diameter of 2-0.85 mm were prepared by mixing sands and crushed mudstone to reach the prescribed mudstone content defined by dry mass ranging from 0% to 50%.The mixtures were subjected to immersion under a certain stress level and were subsequently tested.In addition,one-dimensional compression tests were also supplementally performed to visually observe the immersion-induced degradation of crushed mudstone.The test results mainly showed that: (1) the liquefaction resistance,the post-liquefaction undrained strength,and the undrained strength without a precedent cyclic-loading history decreased significantly with increasing mudstone content,M c ,up to 20%;(2) even a small amount of crushed mudstone affected these strengths;(3) the above-mentioned large reductions in the strengths were attributed to the immersion-induced degradation of crushed mudstone;(4) at M_(c) >20%,the liquefaction resistance increased while the significant increase in the undrained static strengths with and without precedent cyclic-loading histories was not observed;and (5) the increase in the liquefaction resistance at M_(c) >20% may have been attributed to both the gradual increase in the plasticity and the formation of the soil aggregates among deteriorated crushed mudstone,while the increase in the specimen density did not play an important role in such behavior. 展开更多
关键词 liquefaction Post-liquefaction behavior Triaxial test Sands containing crushed mudstone
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Effect of particle composition and consolidation degree on the wave-induced liquefaction of soil beds
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作者 Zhiyuan Chen Yupeng Ren +1 位作者 Guohui Xu Meng Li 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第2期11-22,共12页
The wave-induced liquefaction of seabed is responsible for causing damage to marine structures.Particle composition and consolidation degree are the key factors affecting the pore water pressure response and liquefact... The wave-induced liquefaction of seabed is responsible for causing damage to marine structures.Particle composition and consolidation degree are the key factors affecting the pore water pressure response and liquefaction behavior of the seabed under wave action.The present study conducted wave flume experiments on silt and silty fine sand beds with varying particle compositions.Furthermore,a comprehensive analysis of the differences and underlying reasons for liquefaction behavior in two different types of soil was conducted from both macroscopic and microscopic perspectives.The experimental results indicate that the silt bed necessitates a lower wave load intensity to attain the liquefaction state in comparison to the silty fine sand bed.Additionally,the duration and development depth of liquefaction are greater in the silt bed.The dissimilarity in liquefaction behavior between the two types of soil can be attributed to the variation in their permeability and plastic deformation capacity.The permeability coefficient and compression modulus of silt are lower than those of silty fine sand.Consequently,silt is more prone to the accumulation of pore pressure and subsequent liquefaction under external loading.Prior research has demonstrated that silt beds with varying consolidation degrees exhibit distinct initial failure modes.Specifically,a dense bed undergoes shear failure,whereas a loose bed experiences initial liquefaction failure.This study utilized discrete element simulation to examine the microscopic mechanisms that underlie this phenomenon. 展开更多
关键词 wave flume liquefaction pore water pressure consolidation permeability experiment discrete element simulation
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Storm Liquefaction Deposits:A Possibility of Time Reversal in Sedimentary Strata of an Estuarial Coastal Area
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作者 XU Guohui REN Yupeng +3 位作者 HU Guanghai LIU Zhiqin SUN Yongfu LIN Lin 《Journal of Ocean University of China》 SCIE CAS CSCD 2024年第4期961-969,共9页
In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume exper... In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume experiment demonstrated that storm-induced liquefaction deposits are formed by the oscillations of liquefied sediments.In this paper,the particle size distribution and ^(210)Pb_(ex) specific activity of the sediment samples from the liquefaction disturbed zone and adjacent stable zone of the Yellow River Delta were tested.The stratigraphic divisions based on storm liquefaction deposit sequence can effectively explain the vertical changes in particle size and ^(210)Pb_(ex) specific activity.Due to the differentiation of particles during the storm induced liquefaction,coarse and fine particles regrouped,which could explain the phenomenon of time-reversal in dating data. 展开更多
关键词 ^(210)Pb_(ex)specific activity liquefaction deposition REVERSAL sediment
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The Effect of Preloading on the Cyclic Liquefaction Strength Measured in the Laboratory
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作者 Konstantinos Stamatopoulos 《Journal of Civil Engineering and Architecture》 2024年第6期269-275,共7页
The effect of preloading on the liquefaction cyclic strength was investigated by cyclic shear tests where horizontal shear stress oscillated about a zero mean value on sands with varying fines content and at varying p... The effect of preloading on the liquefaction cyclic strength was investigated by cyclic shear tests where horizontal shear stress oscillated about a zero mean value on sands with varying fines content and at varying prestress ratios, densities and verticalstresses. Test results showed a marked increase of the cyclic soil strength with the prestress ratio. The effect is more pronounced for the looser specimens. An empirical expression predicting this effect is proposed. This expression is validated from results of a field test. 展开更多
关键词 Cyclic liquefaction shear stress field test
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Constitutive modelling of fabric effect on sand liquefaction 被引量:3
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作者 Zhiwei Gao Dechun Lu +1 位作者 Yue Hou Xin Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第4期926-936,共11页
Sand liquefaction under static and dynamic loading can cause failure of embankments,slopes,bridges and other important infrastructure.Sand liquefaction in the seabed can also cause submarine landslides and tsunamis.Fa... Sand liquefaction under static and dynamic loading can cause failure of embankments,slopes,bridges and other important infrastructure.Sand liquefaction in the seabed can also cause submarine landslides and tsunamis.Fabric anisotropy related to the internal soil structure such as particle orientation,force network and void space is found to have profound influence on sand liquefaction.A constitutive model accounting for the effect of anisotropy on sand liquefaction is proposed.Evolution of fabric anisotropy during loading is considered according to the anisotropic critical state theory for sand.The model has been validated by extensive test results on Toyoura sand with different initial densities and stress states.The effect of sample preparation method on sand liquefaction is qualitatively analysed.The model has been used to investigate the response of a sand ground under earthquake loading.It is shown that sand with horizontal bedding plane has the highest resistance to liquefaction when the sand deposit is anisotropic,which is consistent with the centrifuge test results.The initial degree of fabric anisotropy has a more significant influence on the liquefaction resistance.Sand with more anisotropic fabric that can be caused by previous loading history or compaction methods has lower liquefaction resistance. 展开更多
关键词 SAND ANISOTROPY liquefaction Finite element modelling Constitutive model
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Liquefaction proneness of stratified sand-silt layers based on cyclic triaxial tests 被引量:2
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作者 Arpit Jain Satyendra Mittal Sanjay Kumar Shukla 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第7期1826-1845,共20页
Most studies on liquefaction have addressed homogeneous soil strata using sand or sand with fine content without considering soil stratification.In this study,cyclic triaxial tests were conducted on the stratified san... Most studies on liquefaction have addressed homogeneous soil strata using sand or sand with fine content without considering soil stratification.In this study,cyclic triaxial tests were conducted on the stratified sand specimens embedded with the silt layers to investigate the liquefaction failures and void-redistribution at confining stress of 100 kPa under stress-controlled mode.The loosening of underlying sand mass and hindrance to pore-water flow caused localized bulging at the sand-silt interface.It is observed that at a silt thickness of 0.2H(H is the height of the specimen),nearly 187 load cycles were required to attain liquefaction,which was the highest among all the silt thicknesses with a single silt layer.Therefore,0.2H is assumed as the optimum silt thickness(t_(opt)).The silt was placed at the top,middle and bottom of the specimen to understand the effect of silt layer location.Due to the increase in depth of the silt layer from the top position(capped soil state)to the bottom,the cycles to reach liquefaction(N_(cyc,L))increased 2.18 times.Also,when the number of silt layers increased from single to triple,there was an increase of about 880%in N_(cyc,L).The micro-characterization analysis of the soil specimens indicated silty materials transported in upper sections of the specimen due to the dissipated pore pressure.The main parameters,including thickness(t),location(z),cyclic stress ratio(CSR),number of silt layers(n)and modified relative density(D_(r,m)),performed significantly in governing the lique-faction resistance.For this,a multilinear regression model is developed based on critical parameters for prediction of N_(cyc,L).Furthermore,the developed constitutive model has been validated using the data from the present study and earlier findings. 展开更多
关键词 Cyclic triaxial tests Soil stratification Soil liquefaction Regression model
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Seismic Liquefaction Resistance Based on Strain Energy Concept Considering Fine Content Value Effect and Performance Parametric Sensitivity Analysis 被引量:1
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作者 Nima Pirhadi Xusheng Wan +3 位作者 Jianguo Lu Jilei Hu Mahmood Ahmad Farzaneh Tahmoorian 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第4期733-754,共22页
Liquefaction is one of the most destructive phenomena caused by earthquakes,which has been studied in the issues of potential,triggering and hazard analysis.The strain energy approach is a common method to investigate... Liquefaction is one of the most destructive phenomena caused by earthquakes,which has been studied in the issues of potential,triggering and hazard analysis.The strain energy approach is a common method to investigate liquefaction potential.In this study,two Artificial Neural Network(ANN)models were developed to estimate the liquefaction resistance of sandy soil based on the capacity strain energy concept(W)by using laboratory test data.A large database was collected from the literature.One group of the dataset was utilized for validating the process in order to prevent overtraining the presented model.To investigate the complex influence of fine content(FC)on liquefaction resistance,according to previous studies,the second database was arranged by samples with FC of less than 28%and was used to train the second ANN model.Then,two presented ANN models in this study,in addition to four extra available models,were applied to an additional 20 new samples for comparing their results to show the capability and accuracy of the presented models herein.Furthermore,a parametric sensitivity analysis was performed through Monte Carlo Simulation(MCS)to evaluate the effects of parameters and their uncertainties on the liquefaction resistance of soils.According to the results,the developed models provide a higher accuracy prediction performance than the previously publishedmodels.The sensitivity analysis illustrated that the uncertainties of grading parameters significantly affect the liquefaction resistance of soils. 展开更多
关键词 liquefaction resistance capacity strain energy artificial neural network sensitivity analysis Monte Carlo Simulation
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Application of machine learning to the Vs-based soil liquefaction potential assessment
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作者 SUI Qi-ru CHEN Qin-huang +1 位作者 WANG Dan-dan TAO Zhi-gang 《Journal of Mountain Science》 SCIE CSCD 2023年第8期2197-2213,共17页
Earthquakes can cause violent liquefaction of the soil, resulting in unstable foundations that can cause serious damage to facilities such as buildings, roads, and dikes. This is a primary cause of major earthquake di... Earthquakes can cause violent liquefaction of the soil, resulting in unstable foundations that can cause serious damage to facilities such as buildings, roads, and dikes. This is a primary cause of major earthquake disasters. Therefore, the discrimination and prediction of earthquake-induced soil liquefaction has been a hot issue in geohazard research. The soil liquefaction assessment is an integral part of engineering practice. This paper evaluated a dataset of 435 seismic sand liquefaction events using machine learning algorithms. The dataset was analyzed using seven potential assessment parameters. Ten machine learning algorithms are evaluated for their ability to assess seismic sand liquefaction potential, including Linear Discriminant Analysis(LDA), Quadratic Discriminant Analysis(QDA), Naive Bayes(NB), KNearest Neighbor(KNN), Artificial Neural Network(ANN), Classification Tree(CT), Support Vector Machine(SVM), Random Forest(RF), e Xtreme Gradient Boosting(XGBoost), Light Gradient Boosting Machine(Light GBM). A 10-fold cross-validation(CV) method was used in the modeling process to verify the predictive performance of the machine learning models. The final percentages of significant parameters that influenced the prediction results were obtained as Cyclic Stress Ratio(CSR) and Shear-Wave Velocity( VS1) with 56% and 38%, respectively. The final machine learning algorithms identified as suitable for seismic sand liquefaction assessment were the CT, RF, XGBoost algorithms, with the RF algorithm performing best. 展开更多
关键词 Seismic soil liquefaction Machine learning ASSESSMENT liquefaction potential shear wave velocity
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Kinetics and Process Studies of the Potential for Transformation of Biogas to Biomethane and Liquefaction using Cryogenic Liquid for Domestic Applications
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作者 Benard Ogembo Paul Njogu Francis Ochieng 《Energy and Power Engineering》 2023年第6期229-240,共12页
The present work dealt with the generation, purifying and liquefaction of biomethane to improve energy density using local materials for domestic applications. Cow dung was sourced at JKUAT dairy farm and experiments ... The present work dealt with the generation, purifying and liquefaction of biomethane to improve energy density using local materials for domestic applications. Cow dung was sourced at JKUAT dairy farm and experiments were conducted at JKUAT Bioenergy laboratory using biogas generated in laboratory scale 1 m<sup>3</sup> bioreactors. Experiments were done in triplicates and repeated under different conditions to get the optimal conditions. The results showed that enhanced cow dung substrate displayed an improved fermentation process with increased biogas yields. Purified biogas optimized methane content from 56% ± 0.18% for raw biogas to 95% ± 0.98% for biomethane which was ideal for liquefaction. 展开更多
关键词 BIOGAS Bio-Methane Catalysis PURIFICATION liquefaction BIO-ENERGY KINETICS
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Effects of non-liquefiable crust layer and superstructure mass on the response of 2×2 pile groups to liquefaction-induced lateral spreading
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作者 S.Mohsen Haeri Morteza Rajabigol +2 位作者 Saman Salaripour Hiwa Sayaf Milad Zangeneh 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第10期2701-2719,共19页
In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spr... In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spreading.In this regard,an inclined base layer overlain by a very loose liquefiable layer was constructed in both models;while only in one model,a non-liquefiable crust layer was built.A lumped mass,being representative of a superstructure,was attached to the cap of one pile group in both models.The models were fully instrumented with various sensors,including acceleration,displacement,and pore water pressure transducers.Also,the piles were instrumented with pair strain gauges to measure pure bending moments induced by cyclic and monotonic loadings associated with ground shaking and lateral spreading,respectively.The results showed that the existence of the non-liquefiable crust layer increases both the maximum and residual soil displacements at the free field and also the maximum bending moments in the piles.The results of the experiments indicated that the crust layer induces a high kinematic lateral soil pressure and force on the piles which are not present in the crustless case.The crust layer increases the pile cap displacement before liquefaction,albeit decreases it after liquefaction,due to the elastic rebound of the piles in the liquefiable layer.The crust layer postpones both liquefaction triggering and dissipation of excess pore water pressure.The existence of the superstructure mass on the pile caps decreases the acceleration amplitude of the pile caps,while increases their maximum displacement. 展开更多
关键词 Soil liquefaction Lateral spreading 1g shake table test Pile group Crust layer SUPERSTRUCTURE
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Calibration of an elastoplastic model of sand liquefaction using the swarm intelligence with a multi-objective function
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作者 Qiutong Li Zhehao Zhu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第3期789-802,共14页
According to post-seismic observations,spectacular examples of engineering failures can be ascribed to the occurrence of sand liquefaction,where a sandy soil stratum could undergo a transient loss of shear strength an... According to post-seismic observations,spectacular examples of engineering failures can be ascribed to the occurrence of sand liquefaction,where a sandy soil stratum could undergo a transient loss of shear strength and even behave as a“liquid”.Therefore,correct simulation of liquefaction response has become a challenging issue in geotechnical engineering field.In advanced elastoplastic models of sand liquefaction,certain fitting parameters have a remarkable effect on the computed results.However,the identification of these parameters,based on the experimental data,is usually intractable and sometimes follows a subjective trial-and-error procedure.For this,this paper presented a novel calibration methodology based on an optimization algorithm(particle swarm optimization(PSO))for an advanced elastoplastic constitutive model.A multi-objective function was designed to adjust the global quality for both monotonic and cyclic triaxial simulations.To overcome computational problem probably appearing in simulation of the cyclic triaxial test,two interrupt mechanisms were designed to prevent the particles from wasting time in searching the unreasonable space of candidate solutions.The Dafalias model has been used as an example to demonstrate the main programme.With the calibrated parameters for the HN31 sand,the computed results were highly consistent with the laboratory experiments(including monotonic triaxial tests under different confining pressures and cyclic triaxial tests in two loading modes).Finally,an extension example is given for Ottawa sand F65,suggesting that the proposed platform is versatile and can be easily customized to meet different practical needs. 展开更多
关键词 Particle swarm optimization(PSO) Sand liquefaction Elastoplastic constitutive model Triaxial test
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Study regarding typical liquefaction damage during the 2021 Maduo M_(s)7.4 earthquake in China
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作者 Yuan Jinyuan Wang Yunlong +4 位作者 Ma Jiajun Zhan Beilei Yuan Xiaoming Wang Lanmin Wu Xiaoyang 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第4期895-908,共14页
The most important method of understanding liquefaction-induced engineering failures comes from the investigation and analysis of earthquake damage.In May 2021,the Maduo M_(s)7.4 earthquake occurred on the Tibetan Pla... The most important method of understanding liquefaction-induced engineering failures comes from the investigation and analysis of earthquake damage.In May 2021,the Maduo M_(s)7.4 earthquake occurred on the Tibetan Plateau of China.The most representative engineering disaster caused by this earthquake was bridge damage on liquefied sites.In this study,the mutual relationships between the anti-liquefaction pre-design situation,the ground motion intensity,the site liquefaction severity,and the bridge damage state for this earthquake were systematically analyzed for typical bridge damage on the liquefied sites.Using field survey data and the current Chinese industry code,simulations of the liquefaction scenarios at typical bridge sites were performed for the pre-design seismic ground motion before the earthquake and the seismic ground motion during the earthquake.By combining these results with post-earthquake investigation results,the reason for the serious bridge damage resulting from this earthquake is revealed,and the necessary conditions for avoiding serious seismic damage to bridges built in liquefiable sites is presented. 展开更多
关键词 seismic liquefaction Maduo M_(s)7.4 earthquake bridge damage seismic code
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Fabric characteristics of in situ sand with/without liquefaction verified by anisotropy of magnetic susceptibility
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作者 Xueqian Ni Junnan Ma +1 位作者 Hide Sakaguchi Feng Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第5期1274-1283,共10页
It is well known that fabric of sand may significantly affect mechanical behaviors and liquefaction resistance of sand.Various optical techniques are currently utilized to visualize the fabric,especially the distribut... It is well known that fabric of sand may significantly affect mechanical behaviors and liquefaction resistance of sand.Various optical techniques are currently utilized to visualize the fabric,especially the distribution of the long axis of soil particles.However,none of these methods provides an ideal solution in laboratory tests and in situ observation.In this study,anisotropy of magnetic susceptibility(AMS)was first proposed as a convenient and efficient way to evaluate the liquefaction of clean sand.At first,investigations with scanning electron microscopy(SEM)and AMS were simultaneously conducted on two groups of soil specimens with different initial fabrics to verify the feasibility of the AMS technique.Then,80 in situ samples were collected to analyze the feature of liquefied and non-liquefied sand layers through AMS tests.It is clearly known from the test results that the natural sedimentary fabric was destroyed during liquefaction and the fabric anisotropy was greatly changed after liquefaction.The feasibility of evaluating soil fabric using the AMS survey was verified by the laboratory tests.Furthermore,the applicability of AMS in detecting liquefied layer in situ was confirmed for the first time. 展开更多
关键词 Sand liquefaction Soil fabric Anisotropy of magnetic susceptibility(AMS) Geotechnical seismic engineering
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Effect of Refrigerant on the Performance of a C3/MRC Liquefaction Process
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作者 Xiao Wu Zhaoting Wang +2 位作者 Longfei Dong Yanping Xin Tianshu Yu 《Fluid Dynamics & Materials Processing》 EI 2023年第1期25-36,共12页
The Mixed Refrigerant(MR)component is an important factor influencing the performances of natural gas lique-faction processes.However,there is a lack of systematic research about the utilization of propane pre-cooled(... The Mixed Refrigerant(MR)component is an important factor influencing the performances of natural gas lique-faction processes.However,there is a lack of systematic research about the utilization of propane pre-cooled(C3/MRC).In this paper,this mixed refrigerant cycle liquefaction process is simulated using the HYSYS software and the main influential parameters involved in the process are varied to analyze their influence on the liquefaction rate and power consumption.The results show that an effective way for lowering the power consumption of the compressor consists of reducing the flow through the compressor through optimization of the percentage of mixed refrigerant.The power consumption of the compressor in the hybrid refrigeration process is affected by both flow and pressure ratios.Its specific power consumption can be reduced by increasing the flow and decreasing the pressure ratio at the same time.The increase in refrigerant pressure at the high-pressure end can significantly mitigate the energy loss of the heat exchanger and compressor. 展开更多
关键词 REFRIGERANT C3/MRC process liquefaction performance power consumption pressure ratio hybrid refrigeration process
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