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Comparative Experimental Study on Heat Transfer Characteristics of Building Exterior Surface at High and Low Altitudes

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Journal of Thermal Science 2024年第3期33卷 1119-1131页

作者： JIA Yonghong GUO Shurui LI Jin GUO Lei CHENG Zhu ZHANG Yin YANG Hanyu LONG Enshen institute for disaster management and reconstruction Sichuan UniversityChengdu610065China MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu610065China

The external surface heat transfer coefficient of building envelope is one of the important parameters necessary for building energy saving design,but the basic data in high-altitude area are ***,the authors propose a modified measurement method based on the heat balance of a model building,and use the same model building to measure its external surface heat transfer coefficient under outdoor conditions in Chengdu city,China at an altitude of 520 m and Daocheng city at an altitude of 3750 m *** results show that the total heat transfer coefficient(h_(t))of building surface in high-altitude area is reduced by 34.48%.The influence of outdoor wind speed on the convective heat transfer coefficient(h_(c))in high-altitude area is not as significant as that in low-altitude *** fitting relation between convection heat transfer coefficient and outdoor wind speed is also *** the same heating power,the average temperature rise of indoor and outdoor air at highaltitude is 41.9%higher than that at low altitude,and the average temperature rise of inner wall is 25.8%higher than that at low *** shows that high-altitude area can create a more comfortable indoor thermal environment than low-altitude area under the same energy consumption *** is not appropriate to use the heat transfer characteristics of the exterior surface of buildings in low-altitude area for building energy saving design and related heating equipment selection and system terminal matching design in high-altitude area.

关键词： altitude heat transfer characteristics convective heat transfer coefficient(h_(c)) radiative heat transfer coefficient(h_(r)) external building envelope

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Effect of dynamic loading orientation on fracture properties of surrounding rocks in twin tunnels

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 393-409页

作者： Ze Deng Zheming Zhu Lei Zhou Leijun Ma Jianwei Huang Yao Zhang Key Laboratory of Deep Earth and Engineering(Ministry of Education) College of Architecture and EnvironmentSichuan UniversityChengdu610065China Failure Mechanics and Engineering disaster Prevention Key Laboratory of Sichuan Province College of Architecture and EnvironmentSichuan UniversityChengdu610065China institute for disaster management and reconstruction Sichuan UniversityChengdu610065China

For expedited transportation,vehicular tunnels are often designed as two adjacent tunnels,which frequently experience dynamic stress waves from various orientations during blasting *** analyze the impact of dynamic loading orientation on the stability of the twin-tunnel,a split Hopkinson pressure bar(SHPB)apparatus was used to conduct a dynamic test on the twin-tunnel *** two tunnels were rotated around the specimen’s center to consider the effect of dynamic loading ***-DYNA software was used for numerical simulation to reveal the failure properties and stress wave propagation law of the twin-tunnel *** findings indicate that,for a twin-tunnel exposed to a dynamic load from different orientations,the crack initiation position appears most often at the tunnel corner,tunnel spandrel,and tunnel *** the impact direction is created by a certain angle(30°,45°,60°,120°,135°,and 150°),the fractures are produced in the middle of the line between the left tunnel corner and the right tunnel *** the impact loading angle(a)is 90°,the tunnel sustains minimal damage,and only tensile fractures form in the surrounding *** orientation of the impact load could change the stress distribution in the twin-tunnel,and major fractures are more likely to form in areas where the tensile stress is concentrated.

关键词： Twin-tunnel Dynamic load Split Hopkinson pressure bar(SHPB) Fracture mode Stress distribution Displacement field distribution

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Factors contributing to the oxygen concentration over the Qinghai-Tibetan Plateau and its contribution rate calculation

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Science China Earth Sciences 2024年第2期67卷 497-509页

作者： Peijun SHI Ying ZHANG Yanqiang CHEN Wenquan ZHU Xiaokang HU Heyi YANG Lu JIANG Yonggui MA Haiping TANG State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing100875China Key Laboratory of Environmental Change and Natural disaster Ministry of EducationBeijing Normal UniversityBeijing100875China The institute for disaster management and reconstruction Sichuan UniversityChengdu610065China Academy of Plateau Science and Sustainability People’s Government of Qinghai Province&Beijing Normal UniversityXining810016China

A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global *** Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;however,knowledge of the factors contributing to its atmospheric oxygen concentration is still ***,we conducted joint observations of ecosystem oxygen production and carbon sinks and near-surface atmospheric oxygen concentrations on the Qinghai-Tibetan Plateau and meteorological elements at Beijing Fangshan *** seasonal differences and statistical methods,we calculated the relative contribution rates of vegetation to changes in atmospheric oxygen *** results indicate that solar radiation,atmospheric humidity,and ecosystem oxygen consumption and production have a significant impact on the atmospheric oxygen concentration,and the impact shows temporal and spatial *** significantly impacts the oxygen concentration,with a contribution rate of 16.7%–24.5%,which is underestimated in existing *** findings provide important insights into the factors that influence atmospheric oxygen concentration and highlight the contribution of *** better understand the oxygen dynamics of the Qinghai-Tibetan Plateau,we recommend further field observations of soil respiration and vegetation photosynthesis to clarify the contributions of carbon storage,carbon sinks and other factors to the near-surface atmospheric oxygen concentration.

关键词： Qinghai-Tibetan Plateau Oxygen concentration Relative contribution rate Air temperature Vegetation

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Stability analysis of intermittently jointed rock slopes based on the stepped failure mode

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Journal of Mountain Science 2024年第3期21卷 1019-1035页

作者： LI Dejian FU Junwen LI Hekai CHENG Xiao ZHAO Lianheng ZHANG Yingbin PENG Xinyan School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China institute for disaster management and reconstruction College of Architecture&EnvironmentSichuan UniversityChengdu 610065China School of Civil Engineering Key Laboratory of Heavy-Haul Railway Engineering StructureMinistry of EducationHunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering StructureCentral South UniversityChangsha 410075China

In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock *** for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure *** on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock *** sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also *** reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are *** results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and *** particular,with the increase in Kφand Kc,Fs increases by approximately 52.

关键词： Jointed rock slopes Stepped sliding failure Weakening characteristics Modified M‒C failure criterion

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Seismic performance evaluation of water supply pipes installed in a full-scale RC frame structure based on a shaking table test

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 163-178页

作者： Wu Houli Guo Endong Wang Jingyi Dai Xin Dai Chenxi Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much *** paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame *** material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic *** response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical *** acceleration response and displacement response of different combinations are *** results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes.

关键词： water supply pipe different materials shaking table test amplification factor seismic fragility

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Dynamic mechanical characteristics of deep Jinping marble in complex stress environments

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 630-644页

作者： Chendi Lou Heping Xie Ru Zhang Hai Ren Hao Luo Kun Xiao Yuan Peng Qiang Tan Li Ren institute for disaster management and reconstruction Sichuan UniversityChengdu610207China College of Water Resource&Hydropower Sichuan UniversityChengdu610065China MOE Key Laboratory of Deep Earth Science&Engineering Sichuan UniversityChengdu610065China Yalong River Hydropower Development Company Ltd.Chengdu610051China (Chongqing)International Engineering Technology Company Ltd.Chongqing401121China

To reveal the dynamic mechanical characteristics of deep rocks,a series of impact tests under triaxial static stress states corresponding to depths of 300-2400 m were *** results showed that both the strain rates and the stress environments in depth significantly affect the mechanical characteristics of *** sensitivity of strain rate to the dynamic strength and deformation modulus shows a negative correlation with depth,indicating that producing penetrative cracks in deep environments is more difficult when damage *** dynamic strength shows a tendency to decrease and then increase slightly,but decreases sharply *** demonstrates a similar trend as that of strength,whereas reflectivity indicates the opposite ***,two critical depths with high dynamically induced hazard possibilities based on the China Jinping Underground Laboratory(CJPL)were proposed for deep *** first critical depth is 600-900 m,beyond which the sensitivity of rock dynamic characteristics to the strain rate and restraint of circumferential stress decrease,causing instability of surrounding rocks under axial stress *** second one lies at 1500-1800 m,where the wave impedance and dynamic strength of deep surrounding rocks drop sharply,and the dissipation energy presents a negative *** suggests that the dynamic instability of deep surrounding rocks can be divided into dynamic load dominant and dynamic load induced types,depending on the second critical depth.

关键词： Rock mechanics Split-Hopkinson pressure bar Coupled static‒dynamic loading Different depths Holmquist-Johnson-Cook(HJC)model

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Numerical Simulation of the Seismic Response of a Horizontal Storage Tank Based on a SPH-FEM Coupling Method

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1655-1678页

作者： Peilei Yan Endong Guo HouliWu Liangchao Zhang Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin150080China Key Laboratory of Earthquake disaster Mitigation Ministry of Emergency ManagementHarbin150080China

A coupled numerical calculation method combining smooth particle hydrodynamics(SPH)and the finite element method(FEM)was implemented to investigate the seismic response of horizontal storage *** of a horizontal storage tank featuring a free liquid surface under seismic action was constructed using the SPH–FEM coupling *** stored liquid was discretized using SPH particles,while the tank and supports were discretized using the *** interaction between the stored liquid and the tank was simulated by using the meshless particle contact ***,the numerical simulation results were compared and analyzed against seismic simulation shaking table test data to validate the ***,a series of numerical models,considering different liquid storage volumes and seismic effects,were constructed to obtain time history data of base shear and top center displacement,which revealed the seismic performance of horizontal storage *** simulation results and experimental data showed good agreement,with an error rate of less than 18.85%.And this conformity signifies the rationality of the SPH-FEM coupling *** base shear and top center displacement values obtained by the coupled SPH-FEM method were only 53.3% to 69.1% of those calculated by the equivalent mass method employed in the current *** the stored liquid volume increased,the seismic response of the horizontal storage tank exhibited a gradual upward trend,with the seismic response increasing from 73% to 388% for every 35% increase in stored liquid *** maximum von Mises stress of the tank and the supports remained below the steel yield strength during the *** coupled SPH-FEM method holds certain advantages in studying the seismic problems of tanks with complex structural forms,particularly due to the representation of the flow field distribution during earthquakes by involving reservoir fluid participation.

关键词： SPH-FEM coupling method horizontal storage tank seismic response sloshing

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Projections of summer light rain frequency in typical terrain over eastern China under wind speed constraint

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Science China Earth Sciences 2024年第6期67卷 1885-1894页

作者： Xuechen DONG Daoyi GONG Cuicui SHI institute of disaster Risk Science Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Key Laboratory of Environmental Change and Natural disaster MOEFaculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China School of National Safety and Emergency management Beijing Normal UniversityBeijing 100875China School of Systems Science Beijing Normal UniversityBeijing 100875China

The variation in near-surface wind speed is a key dynamic parameter in the orographic effect of precipitation over eastern *** this study,we used the latest high-resolution outputs from six GCMs in CMIP6-HighResMIP to evaluate the performance of high-resolution models in simulating the orographic precipitation characteristics of typical mountainous areas in summer over eastern *** orographic precipitation under warming scenarios was projected and constrained according to observational *** results indicated that during the contemporary climate reference period(1979-2009),although the relationship between model-simulated near-surface wind speed and orographic light rain frequency was consistently stable,the sensitivity of the orographic light rain frequency to surface wind variability was generally underestimated,with a deviation approximately 24.1% lower than the observational *** estimated orographic light rain frequency corrected based on the observed near-surface wind speed under a 1.5℃ warming scenario,was 36.1% lower than that of the contemporary period;this reduction was 8.6 times that without the wind speed constraint(4.2%).The MRI-AGCM3-2-S model,with a longer dataset,demonstrated relatively stable reductions in orographic light rain frequency under different warming scenarios(1.5℃,2℃,3℃,and 4℃)after the application of wind speed *** all cases,the reductions exceeded those for the predictions made without the wind speed constraint.

关键词： Frequency of orographic light rain HighResMIP High-resolution projection Observational constraint Eastern China

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A Sustainable Strategy for Spent Cathode Carbon Blocks Hazardous Waste Recycling Using Binary Molten Salt Thermal Treatment

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Journal of Thermal Science 2024年第3期33卷 1082-1093页

作者： LI Bin DING Yan JIAO Yuyong XU Fang WANG Xinyang ZHENG Fei ZOU Junpeng GAO Qiang HU Hongyun Faculty of Engineering China University of GeosciencesWuhan430074China institute for Natural disaster Risk Prevention and Emergency management China University of GeosciencesWuhan430074China State Key Laboratory of Coal Combustion Huazhong University of Science and TechnologyWuhan430074China

Waste-to-Energy treatment is a promising path to environment and energy management in the *** work detailed a binary molten salt thermal treatment methodology for the detoxification of spent cathode carbon block(SCCB)waste and the recycling of carbonaceous *** thermal behavior of SCCB and SCCB blended with molten salts was *** was found that the NaCl-Na_(2)CO_(3)binary molten salts significantly contributed to reducing pyrolysis onset temperature by 334.3 K compared to that of SCCB itself(i.e.,activation energy of pyrolysis reaction was reduced from 4.24×10^(5)to 2.30×10^(5)J/mol),thus helping to lower thermal treatment energy *** the addition of binary molten salts,the residue after thermal treatment in a horizontal tube furnace experiment was separated into two *** bottom-layer residue was mainly composed of molten *** fluorine content in the form of NaF and CaF_(2)of top-layer residue was reduced significantly while the carbon content remained ***,the leaching concentration of fluoride ion was decreased from 4620 mg/L to 856 mg/*** is noted that the NaF and CaF_(2)can be removed through water-leaching and hydrothermal acid-leaching methods and thus the carbonaceous materials with a calorific value of 17.5 MJ/kg were obtained.

关键词： spent cathode carbon block hazardous solid waste detoxification binary-molten-salt thermal treatment carbon recycling pyrolysis kinetics

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Automated machine learning for rainfall-induced landslide hazard mapping in Luhe County of Guangdong Province,China

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China Geology 2024年第2期7卷 315-329页

作者： Tao Li Chen-chen Xie Chong Xu Wen-wen Qi Yuan-dong Huang Lei Li National institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing 100085China Key Laboratory of Compound and Chained Natural Hazards Dynamics Ministry of Emergency Management of ChinaBeijing 100085China institute of disaster Prevention Sanhe 065201China School of Emergency management Science and Engineering University of Chinese Academy of SciencesBeijing 100049China

Landslide hazard mapping is essential for regional landslide hazard *** main objective of this study is to construct a rainfall-induced landslide hazard map of Luhe County,China based on an automated machine learning framework(AutoGluon).A total of 2241 landslides were identified from satellite images before and after the rainfall event,and 10 impact factors including elevation,slope,aspect,normalized difference vegetation index(NDVI),topographic wetness index(TWI),lithology,land cover,distance to roads,distance to rivers,and rainfall were selected as *** WeightedEnsemble model,which is an ensemble of 13 basic machine learning models weighted together,was used to output the landslide hazard assessment *** results indicate that landslides mainly occurred in the central part of the study area,especially in Hetian and *** 102.44 s were spent to train all the models,and the ensemble model WeightedEnsemble has an Area Under the Curve(AUC)value of92.36%in the test *** addition,14.95%of the study area was determined to be at very high hazard,with a landslide density of 12.02 per square *** study serves as a significant reference for the prevention and mitigation of geological hazards and land use planning in Luhe County.

关键词： Landslide hazard Heavy rainfall Harzard mapping Hazard assessment Automated machine learning Shallow landslide Visual interpretation Luhe County Geological hazards survey engineering

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