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Benefit evaluation of geotechnical projects for debris flow prevention and control based on projection pursuit in Wenchuan County， SW China

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Journal of Earth Science 2022年

作者： Hao Zheng Mingtao Ding Tao Huang Zemin Gao Faculty of Geosciences and Environmental Engineering， Southwest Jiaotong University

Benefit evaluation of debris flow prevention and control projects was one of the essential contents of debris flow prevention and mitigation work. In order to scientifically and quantitatively evaluate the comprehensive benefit of debris flow prevention and control projects， this study identified nine factors as evaluation indicators from economic， social， and ecological aspects. The projection pursuit (PP) model based on the improved particle swarm optimization (IPSO) algorithm was used to construct a mathematical model to evaluate the benefit of debris flow prevention and control projects. The interpolation method was applied to divide the benefit grades. The debris flow prevention and control projects in Qipan gully， Taoguan gully， Chutou gully， Anjia gully， and Mozi gully in Wenchuan county were chosen as typical cases for empirical analysis. The case study revealed that， among the criteria layer indicators， investment per unit of the protected area， investment per unit of the protected population， the amount of water and soil conservation， and reduction rate of accumulation fan had the most significant weights. The social and ecological benefits were found to be the more important in the target layer. The comprehensive benefit of Qipan gully， Taoguan gully， Chutou gully， Anjia gully， and Mozi gully was found to be 4.44， 4.83， 1.95， 3， and 2， respectively. The benefit ranking of the five gullies was consistent with their effectiveness in disaster prevention ranking in the flood season of 2019. Therefore， it could prove that the newly-built benefit evaluation model was practical and feasible， and the evaluation results of the sample could be reasonably interpreted， which verified the effectiveness of the methods.

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Shear weakening behavior at the surface of structural plane of rock

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Yantu Lixue/Rock and Soil Mechanics 2020年 41卷 19-29页

作者： He, Liu Zhao, Zhi-Ming Wu, Guang Liu, Di-Yi Faculty of Geosciences and Environmental Engineering Southwest Jiaotong University Chengdu 611756 China

Based on a series of direct shear test results of structural planes of similar materials of rock mass, the initial morphology of different structural planes Z2, structural surface wall strength JCS and normal stress σn on the shear weakening and failure of structural surfaces are studied under different shear displacement conditions by applying the three-dimensional scanning identification technique. The results show that the surface damage coefficient (N) of the joint surfaces with higher Z2(initial), JCS and σn increases significantly at different shear displacements with the continuous increase of shear displacement. Structural surfaces with a much higher JCS value are dominated by brittle failure, while structural surfaces with a smaller JCS value are dominated by wear-out failure. During the shear process, the weakening of the structural surface morphology is caused by the "shear effect" of the surface protrusion, and also the "filling effect" of the depressed area of the structural plane. Based on the degradation rate of the morphology factor of structural plane Z2(δ) at different shear displacement, the degradation process of joint surface was classified into three stages with the shear displacement: the initial degradation stage, rapid degradation stage, and constant degradation stage. With the increase of Z2(initial), JCS and σn, the segmentation characteristics of degradation of structural planes become much more obvious, and the transformation process of three stages has an accelerating trend. An empirical model of joint surface morphology degradation under the influence of different factors is proposed through the regression analysis. The results indicate that the accurate tracking on the weakening characteristics of the structural surface morphology during the shearing process is beneficial to study the evolution of mechanical properties of the structural surfaces during the shearing process. © 2020, Science Press. All right reserved.

关键词： Surface morphology

Analysis of network traffic flow dynamics based on gravitational field theory

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Chinese Physics B 2013年第6期22卷 670-680页

作者：刘刚李永树张喜平 Faculty of Geosciences and Environmental Engineering Southwest Jiaotong University

For further research on the gravity mechanism of the routing protocol in complex networks, we introduce the concept of routing awareness depth, which is represented by p. On this basis, we define the calculation formula of the gravity of the transmission route for the packet, and propose a routing strategy based on the gravitational field of the node and the routing awareness depth. In order to characterize the efficiency of the method, we introduce an order parameter, η, to measure the throughput of the network by the critical value of phase transition from free flow to congestion, and use the node betweenness centrality, B, to test the transmission efficiency of the network and congestion distribution. We simulate the network transmission performance under different values of the routing awareness depth, ρ. Simulation results show that if the value of the routing awareness depth p is too small, then the gravity of the route is composed of the attraction of very few nodes on the route, which cannot improve the capacity of the network effectively. If the value of the routing awareness depth ρ is greater than the network＇s average distance （l）, then the capacity of the network may be improved greatly and no longer change with the sustainable increment of routing awareness depth p, and the routing strategy performance enters into a constant state. Moreover, whatever the value of the routing awareness depth p, our algorithm always effectively balances the distribution of the betweenness centrality and realizes equal distribution of the network load.

关键词： routing strategy congestion gravitation field complex networks

Characterization of Fe-containing particles in Chengdu,southwest China,using single-particle aerosol mass spectrometry

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Journal of environmental Sciences 2024年第2期136卷 110-120页

作者： Renjiang He Junke Zhang Luyao Chen Wei Zhang Yingwei Xi School of Public Health Southwest Medical UniversityLuzhou 646000China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 611756China Sichuan environmental Monitoring Center Chengdu 610074China

Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest China.The mass concentrations of PM_(2.5)and PM_(10)during the study period were 64±38 and 89±49μg/m~3,respectively,and NO_(2)and particulate matter were high compared with most other regions of China.The Fecontaining particles were divided into seven categories with different mass spectra,sources and aging characteristics.The highest contribution was from Fe mixed with carbonaceous components(Fe-C,23.1%)particles.Fe was more mixed with sulfate than nitrate and therefore the contribution of Fe mixed with sulfate(Fe-S,20.7%)particles was higher than that of Fe mixed with nitrate(Fe-N,12.5%)particles.The contributions from Fe-containing particles related to primary combustion were high in the small particle size range,whereas aged Fecontaining particles and dust-related particles were mostly found in the coarse particle size range.The air masses mainly originated from the west and east of Chengdu,and the corresponding PM_(2.5)concentrations were 79±36 and 55±36μg/m~3,respectively.The west and east air masses showed stronger contributions of Fe-containing particles related to biomass burning(Fe-B)and fossil fuel combustion(Fe-C and Fe-S)particles,respectively.The southwest area contributed the most Fe-containing particles.Future assessments of the effects of Fe-containing particles during heavy pollution period should pay more attention to Fe-C and Fe-S particles.Emission-reduction of Fe-containing particles should consider both local emissions and short-distance transmission from the surrounding areas.

关键词： Fe-containing particles Particle composition Potential source areas Evolution Chengdu

Real-time,single-particle chemical composition,volatility and mixing state measurements of urban aerosol particles in southwest China

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Journal of environmental Sciences 2024年第2期136卷 361-371页

作者： Luyao Chen Junke Zhang Jiaqi Li Xiaojuan Huang Yuzheng Xiang Jing Chen Tingru Pan Wei Zhang Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 611756China School of Atmospheric Sciences Chengdu University of Information TechnologyChengdu 610225China Sichuan environmental Monitoring Center Chengdu 610074China

To investigate the volatility of atmospheric particulates and the evolution of other particulate properties(chemical composition,particle size distribution and mixing state)with temperature,a thermodenuder coupled with a single particle aerosol mass spectrometer was used to conduct continuous observations of atmospheric fine particles in Chengdu,southwest China.Because of their complex sources and secondary reaction processes,the average mass spectra of single particles contained a variety of chemical components(including organic,inorganic and metal species).When the temperature rose from room temperature to280℃,the relative areas of volatile and semi-volatile components decreased,while the relative areas of less or non-volatile components increased.Most(>80%)nitrate and sulfate existed in the form of NH_(4)NO_(3)and(NH_(4))_(2)SO_(4),and their volatilization temperatures were50–100℃and 150–280℃,respectively.The contribution of biomass burning(BB)and vehicle emission(VE)particles increased significantly at 280℃,which emphasized the important role of regional biomass burning and local motor vehicle emissions to the core of particles.With the increase in temperature,the particle size of the particles coated with volatile or semi-volatile components was reduced,and their mixing with secondary inorganic components was significantly weakened.The formation of K-nitrate(KNO_(3))and K-sulfate(KSO_(4))particles was dominated by liquid-phase processes and photochemical reactions,respectively.Reducing KNO_(3)and BB particles is the key to improving visibility.These new results are helpful towards better understanding the initial sources,pollution formation mechanisms and climatic effects of fine particulate matter in this megacity in southwest China.

关键词： Atmospheric fine particles TD-SPAMS Chemical composition Volatility Mixing state

Coulomb stress and gravity changes associated with the 2016 Mw 7.8 Kaikoura Earthquake, New Zealand: Application for aftershock triggering and fault interaction process analysis

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Journal of Mountain Science 2021年第2期18卷 510-527页

作者： HASSAN Abubakr HUANG Ding-fa JIANG Zhong-shan ZHANG Lu-peng Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 611756China Surveying engineering Department Faculty of EngineeringKarary UniversityKhartoum 12304Sudan

The Kaikoura earthquake on November 14,2016 is one of the largest and most complex earthquakes in New Zealand since 1947.Despite the fact that it has ruptured about 12 separate faults,triggered 2132 aftershocks within one week of the mainshock and induced considerable stress changes,few studies have been conducted to comprensively investigate the characteristics.The current study examines the horizontal and vertical displacements as well as the stress and gravity changes,aftershock distributions and also find out whether these changes affect the surrounding regions along the complex fault systems.The study covers the entire area affected by the Kaikoura event,which includes the northern part of the South Island and the southern part of the North Island.The dislocation theory was employed to evaluate the coseismic slip model on the multiple faults.The displacement results revealed that the maximum horizontal displacement is about 6 m and the vertical about 2 m,which are reasonably consistent with earlier study findings.Besides,the stress and gravity changes are quite complicated and inhomogeneous as evidenced by our coseismic model,demonstrating the complexity of the Kaikoura earthquake as well.Almost all the aftershocks are distributed in places where the stress and gravity change are found to be significant.In order to investigate the stability of our stress change models,we applied different friction coefficients and receiver fault parameters.The results justify the friction coefficient(μ=0.4)and the receiver fault parameters(230°,70°,150°)are suitable to define good stress change estimates.According to the stress change results at 15 km depth,the northern parts of the mainshock region,Hundalee fault,Humps fault and Jordan thrust areas together with the Wellington area are closer to failure and situated in a seismic risk zone.The multidimensional analysis adopted in this paper is helpful for making decisions and applications of stress and gravity change models in assessing seismic hazards.

关键词： Aftershock triggering Components displacement Coulomb failure stress Fault interaction Gravity change Kaikoura earthquake

Effect of hydrophilic silica nanoparticles on hydrate formation: Insight from the experimental study

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Journal of Energy Chemistry 2019年第3期28卷 90-100页

作者： Ren Wang Tianle Liu Fulong Ning Wenjia Ou Ling Zhang Zhen Wang Li Peng Jiaxin Sun Zhichao Liu Tianshu Li Huicui Sun Guosheng Jiang faculty of engineering China University of Geosciences CNPC Drilling Research Institute Department of Civil and environmental engineering The George Washington University

Invasion of drilling fluid into natural gas hydrate deposits during drilling might damage the reservoir,induce hydrate dissociation and then cause wellbore instability and distortion of the data from well logging. Adding nanoparticles into drilling fluid is an effective method in reducing the invasion of drilling fluid and enhancing borehole stability. However, the addition of nanoparticles might also introduce hydrate formation risk in borehole because they can act as the "seeds" for hydrate nucleation. This paper presents an experimental study of the effect of hydrophilic silica nanoparticle on gas hydrate formation in a dynamic methane/liquid-water system. In the experiment, the ultrapure water with and without1.0 wt%–6.0 wt% concentrations of silica nanoparticles, grain sizes of 20 and 50 nm, were pressurized by methane gas under varied conditions of temperature and pressure. The induction time, the gas consumption, and the average rate of gas consumption in the system were measured and compared to those in ultrapure water. The results show that a concentration of 4.0 wt% hydrophilic SiO_2 particles with a grain size of 50 nm has a relatively strong inhibition effect on hydrate formation when the initial experimental condition is 5.0 °C and 5.0 MPa. Compared to ultrapure water, the hydrophilic nano-SiO_2 fluid increases the induction time for hydrate formation by 194% and decreases the amount and average rate of hydrate formation by 10% and 17%, respectively. This inhibition effect may be attributed to the hydrophilicity,amount and aggregation of silica nanoparticle according to the results of water activity and zeta potential measurements. Our work also elucidates hydrophilic, instead of hydrophobic, nanoparticles can be added to the drilling fluid to maintain wellbore stability and to protect the hydrate reservoir from drilling mud damage, because they exhibit certain degree of hydrate inhibition which can reduce the risk of hydrate reformation and aggregation during gas hydrate or deep water drilling if th

关键词： Hydrate drilling fluid Hydrophilic nano-SiO2 Concentration Grain size Hydrate formation Inhibition mechanism

Recent Advance on Torrefaction Valorization and Application of Biochar from Agricultural Waste for Soil Remediation

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Journal of Renewable Materials 2022年第2期10卷 247-261页

作者： Kai Su Qirui Qin Jingyu Yang Linxiao Li and Shaoqi Deng Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu611756China

With the increase of global proportion of soil pollution and the number of areas at risk,researchers have sought to develop various pathways to repair or relieve the pollutants in soil.Among them,biochar represents one multi-dimensional soil amendment which has got great deal of attention on its physicochemical properties towards the removal or mitigation of contaminants in soil.A variety of agricultural wastes like straw and manure prepared from different torrefaction process have been employed as feedstock for the production of biochar,which can be applied to the contaminated soil to facilitate the growing environment for crops,and to improve soil fertility and microbial environment.In addition,the utilization of biochar for soil remediation is also considered as a pro-cess of carbon sequestration.The purpose of this review is to summarize the latest research progress in torrefac-tion processes and mechanism of agricultural waste,the effects of different torrefaction methods on the formation and properties of biochar were explained,coupled with the effects of process parameters.Especially,the conver-sion and mechanisms of biochar prepared from agricultural wastes composed mainly with lignocellulosic material were discussed,and the characteristics of biochar prepared for improving soil physical and chemical character-istics,microbial community characteristics,nutrients,and the stability and relief of soil pollutants,especially heavy metals,are compared.Finally,this work discussed the application and future technical challenges of soil remediation based on agricultural waste derived biochar.

关键词： Torrefaction biochar soil remediation agricultural waste

Three-dimensional virtual representation for the whole process of dam-break floods from a geospatial storytelling perspective

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International Journal of Digital Earth 2022年第1期15卷 1637-1656页

作者： Weilian Li Jun Zhu Jan-Henrik Haunert Lin Fu Qing Zhu Youness Dehbi Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengduPeople's Republic of China Institute of Geodesy and Geoinformation University of BonnBonnGermany

The objective of disaster scenes is to share location-based risk information to a large audience in an effective and intuitive way.However,current studies on three-dimensional(3D)representation for dam-break floods have the following limitations:(1)they are lacking a reasonable logic to organize the whole process of dam-break floods,(2)they present information in a way that cannot be easily understood by laypersons.Geospatial storytelling helps to create exciting experiences and to explain complex relationships of geospatial phenomena.This article proposes a three-dimensional virtual representation method for the whole process of dam-break floods from a geospatial storytelling perspective.The creation of a storyline and a storytelling-oriented representation of dam-break floods are discussed in detail.Finally,a prototype system based on WebGL is developed to conduct an experiment analysis.The results of the experiment show that the proposed method can effectively support 3D representation of the spatiotemporal process of dam-break floods.Furthermore,the statistical results indicate that the storytelling is useful for assisting participants in understanding the occurrence and development of dam-break floods,and is applicable to the popularization of disaster science for the general public.

关键词： Geospatial storytelling dam-break flood spatiotemporal process virtual representation 3D scene