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Big Disaster from Small Watershed: Insights into the Failure and Disaster-Causing Mechanism of a Debris Flow on 25 September 2021 in Tianquan, China

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INTERNATIONAL JOURNAL OF DISASTER RISK SCIENCE 2024年第4期15卷 622-639页

作者： Hou, Runing Wu, Mingyang Li, Zhi Chen, Ningsheng Chen, Xiaohu peng, taixin Huang, Na Chinese Acad Sci Key Lab Mt Hazards & Surface Proc Inst Mt Hazards & Environm Chengdu 610041 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Yangtze Univ Sch Geosci Wuhan 430100 Peoples R China Acad Plateau Sci & Sustainabil Xining 810016 Peoples R China

The occurrence of debris flow events in small-scale watersheds with dense vegetation in mountainous areas that result in significant loss of life and missing individuals challenges our understanding and expertise in investigating and preventing these disasters. This has raised concerns about the occurrence of large debris flow disasters from small watersheds. This study focused on a catastrophic debris flow that took place in Longtou Gully (0.45 km2) in Tianquan County, Ya'an City on 25 September 2021, which resulted in 14 deaths and missing individuals. Through comprehensive field investigations, high-precision remote sensing data analyses, and numerical simulations, we analyzed the triggering mechanisms and dynamic processes of this event. Our results indicate that the convergence hollow at the channel head exhibited higher hydraulic conditions during rainfall compared to gentle slopes and convex terrains, leading to the instability of colluvial soil due to the expansion of the saturated zone near the soil-bedrock interface. The entrainment of material eroded from the channel resulted in an approximately 4.7 times increase in volume, and the channel scarp with a height of about 200 m amplified the destructive power of the debris flow. We emphasize the need to take seriously the possibility of catastrophic debris flows in small-scale watersheds, with colluvial deposits in hollows at the channel head under vegetation cover that serve as precursor material sources, and the presence of channel scarps formed by changes in the incision rate of the main river, which is common in the small watershed on both sides. This study provides insights for risk assessment of debris flows in small-scale catchments with dense vegetation cover in mountainous areas, highlighting the importance of vigilance in addressing disasters in small-scale catchments, particularly in regions with increasing human-environment conflicts.

关键词： China Colluvial soil Low-frequency debris flows Risk reduction Topographic hollows HILLSLOPE EROSION SHALLOW LANDSLIDES MODEL ENTRAINMENT RATES SOIL RADIOCARBON TOPOGRAPHY DEPOSITION CATCHMENT

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干流公路桥涵堵塞对泥石流灾害的风险放大效应

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中国地质灾害与防治学报 2024年第5期35卷 120-132页

作者：杨静萍陈宁生杨志全彭泰鑫田树峰黄娜昆明理工大学公共安全与应急管理学院云南昆明650093 中国科学院、水利部成都山地灾害与环境研究所四川成都610299 长江大学地球科学学院湖北武汉430100 高原科学与可持续发展研究院青海西宁810016 中国科学院大学北京100049

2020年8月17日,四川省平武县亚者造祖村干流沿岸4条沟相继暴发泥石流,导致G247国道多处断道和垮方,九绵高速项目部及民工驻地等多处遭受巨大损毁,泥石流裹挟的大量漂木汇入干流后,引发下游公路桥涵堵塞并回水淹没村庄,放大了灾害风险。... 详细信息

2020年8月17日,四川省平武县亚者造祖村干流沿岸4条沟相继暴发泥石流,导致G247国道多处断道和垮方,九绵高速项目部及民工驻地等多处遭受巨大损毁,泥石流裹挟的大量漂木汇入干流后,引发下游公路桥涵堵塞并回水淹没村庄,放大了灾害风险。为了避免类似灾害再次发生,灾后基于野外调查和遥感解译等手段,探讨了此次泥石流灾害风险特征,并重点分析了干流公路桥涵堵塞对泥石流灾害的风险放大效应。结果表明:(1)亚者造祖村“8•17”泥石流为低频稀性大规模群发性泥石流,暴发频率约为50年一遇。阿祖沟和杂排沟泥石流在规模上属特大型,麻石扎三号沟和夺补河五号沟泥石流在规模上属大型,堆积扇受灾面积约为16.66×10^(4) m^(2)。(2)干流公路桥涵布设不当,导致泥石流裹挟的大量漂木堵塞桥涵,形成堰塞体,致使受灾面积增大了16.78×10^(4) m^(2),风险范围扩大了约1倍。(3)对于植被覆盖良好的湿润山区,干流公路桥涵修建时应适当增大桥墩之间的轴向间距,给河道预留出一定的宽度和运行空间,避免因漂木堵塞放大泥石流灾害风险。研究可为类似山区干流公路桥涵合理规划及泥石流相关防治预警工作提供参考。

关键词：泥石流桥涵漂木堵塞风险

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砂土垫层的缓冲效应试验研究

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中国测试 2020年第3期46卷 44-51页

作者：朱大鹏彭泰鑫黄玲西南石油大学地球科学与技术学院四川成都610500

为得到科学的棚洞砂土垫层厚度,提高棚洞的安全性,进行0.5 m、1.0 m、1.5 m高度释放的3 kg、5 kg、7.26 kg落石冲击砂土缩尺试验,监测不同埋深的应力,对比分析不同垫层厚度、落石尺寸和高度的落石冲击效应。高度和落石尺寸一定,如从1.5 ... 详细信息

为得到科学的棚洞砂土垫层厚度,提高棚洞的安全性,进行0.5 m、1.0 m、1.5 m高度释放的3 kg、5 kg、7.26 kg落石冲击砂土缩尺试验,监测不同埋深的应力,对比分析不同垫层厚度、落石尺寸和高度的落石冲击效应。高度和落石尺寸一定,如从1.5 m高度释放的7.26 kg落石,在0.05 m、0.1 m、0.15 m的垫层厚度下,垫层下最大应力分别为1.51 MPa、3.20 MPa、1.19 MPa;落石高度和垫层厚度一定,如从1.5 m释放落石且垫层厚度为0.05 m时,3 kg落石和5 kg落石所对应的垫层下最大应力,分别约为1.15 MPa和1.18 MPa;落石尺寸和垫层厚度一定,如在垫层为0.1 m的情况下,7.26 kg落石从0.5 m、1.0 m和1.5 m释放,分别对应的土中最大应力为1.13 MPa、1.73 MPa和3.20 MPa。随着落石尺寸的增大和释放高度的增加,砂土中应力增大,且增速变快。一定厚度的砂土垫层对落石具有较好的缓冲作用,当厚度再增加,缓冲效果没有明显增强。在实际工程中,可根据棚洞强度、落石高度和落石尺寸来确定砂土垫层厚度。

关键词：落石缓冲效应缩尺试验砂土垫层

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滑移孤石稳定性分析及失稳过程研究——以四川省马边县某孤石为例

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防灾减灾工程学报 2021年第2期41卷 229-237页

作者：彭泰鑫朱大鹏黄玲罗鑫西南石油大学地球科学与技术学院四川成都610500 成都山地灾害与环境研究所山地灾害与地表重点实验室四川成都610041 中国科学院大学北京100049 中国地质科学院探矿工艺研究所四川成都611734

停留在高陡山坡且部分埋入土体的大体积独立崩积物——孤石,在降雨和地震等不良地质情况下会发生失稳破坏并威胁坡脚居民的生命财产安全,独立滑移破坏为孤石的一种主要破坏形式。为了探究独立滑移孤石的滑移力学原理,分析土体物理力学... 详细信息

停留在高陡山坡且部分埋入土体的大体积独立崩积物——孤石,在降雨和地震等不良地质情况下会发生失稳破坏并威胁坡脚居民的生命财产安全,独立滑移破坏为孤石的一种主要破坏形式。为了探究独立滑移孤石的滑移力学原理,分析土体物理力学参数对孤石滑移失稳的影响。基于库伦土压力理论,建立上部楔形体土压力计算模型、下部楔形体模型和左右土体模型,使用Mathematics软件分析模型公式中的抗剪强度、黏聚力和滑裂角等对土压力的影响,并使用Flac3D有限差分法分析滑移孤石的失稳过程。结果显示,上部土体所提供的下滑推力随着抗剪强度和黏聚力值的增大而呈减小趋势,下部土体模型能承受的孤石最大推力约19 kN,当孤石推力大于19 kN时,孤石下部土体将以29.22°的滑裂角滑出;下部土体所提供的抗滑力随着抗剪强度和黏聚力的增大而增大,有限差分法模拟得到了孤石以推动表层土体向临空面滑移的方式失稳。孤石周围土体的抗剪强度和黏聚力对孤石稳定性具有控制作用,降雨使抗剪强度和黏聚力降低是孤石滑移失稳的主要原因。

关键词：孤石崩积物稳定性分析 Mathematics 失稳过程 Flac3D

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Time-Periodic Solutions to Quasilinear Hyperbolic Systems on General Networks

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 41-72页

作者： peng QU School of Mathematical Sciences Fudan UniversityShanghai 200433China

For quasilinear hyperbolic systems on general networks with time-periodic boundary-interface conditions with a dissipative structure,the existence and stability of the time-periodic classical solutions are discussed.

关键词： Time-periodic solution Quasilinear hyperbolic system General net-work Classical solution Asymptotic stability

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Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process

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China Foundry 2024年第1期21卷 82-90页

作者： Kun Gao Yan peng School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina

To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting *** effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in *** each rotation,the casting wheel passes through four different spray *** results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,*** temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.

关键词： casting wheel finite element model grinding thickness casting speed hot face spray zones

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Numerical simulation of fluid flow and free surface fluctuations during wheel and belt casting process

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Journal of Iron and Steel Research International 2024年第5期31卷 1117-1126页

作者： Kun Gao Yan peng National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004HebeiChina

The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast *** lower level height tends to entrap inclusions in the molten *** the other hand,the higher level height makes the production process more dangerous due to the overflow of high temperature fluid from the mold.A computational model of the molten metal pouring process was *** transient fluid flow and free surface fluctuations behavior were calculated using the three-dimensional large eddy simulation model and the volume of fluid *** results show that the flow velocity of the main jet gradually decreases under the influence of the low kinetic energy fluid in the *** is an obvious oscillation in the tail of the jet,while the flow field is asymmetric in *** jet is closer to the inside radius side due to the Coanda effect,and there is a recirculation zone on the inside radius and the outside radius respectively,according to the 10 s time-averaged *** with the industrial observation and simulation results,the shape of the free surface is a wave that varies with *** addition,the free surface height is lowest and the flow velocity is highest in the region near the jet.

关键词： Fluid flow Free surface Wheel and belt caster Large eddy simulation Volume of fluid method

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Two-Stage Online Debiased Lasso Estimation and Inference for High-Dimensional Quantile Regression with Streaming Data

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Journal of Systems Science & Complexity 2024年第3期37卷 1251-1270页

作者： peng Yanjin WANG Lei School of Statistics and Data Science KLMDASRLEBPS and LPMCNankai UniversityTianjin 300071China

In this paper,the authors propose a two-stage online debiased lasso estimation and statistical inference method for high-dimensional quantile regression(QR)models in the presence of streaming *** the first stage,the authors modify the QR score function based on kernel smoothing and obtain the online lasso smoothed QR estimator through iterative *** estimation process only involves the current data batch and specific historical summary statistics,which perfectly accommodates to the special structure of streaming *** the second stage,an online debiasing procedure is carried out to eliminate biases caused by the lasso penalty as well as the accumulative approximation error so that the asymptotic normality of the resulting estimator can be *** authors conduct extensive numerical experiments to evaluate the performance of the proposed *** experiments demonstrate the effectiveness of the proposed method and support the theoretical *** application to the Beijing PM2.5 Dataset is also presented.

关键词： Adaptive tuning asymptotic normality debiased lasso online updating quantile regres-sion

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Electronic origin of structural degradation in Li-rich transition metal oxides:The case of Li_(2)MnO_(3)and Li_(2)RuO_(3)

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Journal of Semiconductors 2024年第4期45卷 82-86页

作者： peng Zhang Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics andOp toelec-tronic EngineeringShenzhen UniversityShenzhen 518060China

Li_(2)MnO_(3)and Li_(2)RuO_(3)represent two prototype Li-rich transition metal(TM)oxides as high-capacity cathodes for Li-ion batteries,which have similar crystal structures but show quite different cycling ***,based on the first-princi-ples calculations,we systematically studied the electronic structures and defect properties of these two Li-rich cathodes,in order to get more understanding on the structural degradation mechanism in Li-rich TM *** calculations indicated that the structural and cycling stability of Li_(2)MnO_(3)and Li_(2)RuO_(3)depend closely on their electronic structures,especially the energy of their highest occupied electronic states(HOS),as it largely determines the defect properties of these *** Li_(2)MnO_(3)with low-energy HOS,we found that,due to the defect charge transfer mechanism,various defects can form spontaneously in its host structure as Li ions are extracted upon delithiation,which seriously deteriorates its structural and cycling *** for Li_(2)RuO_(3),on the other hand,we identified that the high-energy HOS prevents it from the defect formation upon delithi-ation and thus preserve its cycling *** studies thus illustrated an electronic origin of the structural degradation in Li-rich TM oxides and implied that it is possible to improve their cycling performances by carefully adjusting their TM compo-nents.

关键词： defects Li-ion batteries first-principles calculations

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Fourth-order phase-field modeling for brittle fracture in piezoelectric materials

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 837-856页

作者： Yu TAN Fan peng Chang LIU Daiming peng Xiangyu LI State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Science Chang'an UniversityXi'an 710064China Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Failure analyses of piezoelectric structures and devices are of engineering and scientific *** this paper,a fourth-order phase-field fracture model for piezoelectric solids is developed based on the Hamilton *** typical electric boundary conditions are involved in the present model to characterize the fracture behaviors in various physical situations.A staggered algorithm is used to simulate the crack *** polynomial splines over hierarchical T-meshes(PHT-splines)are adopted as the basis function,which owns the *** numerical simulations are performed to study the influence of the electric boundary conditions and the applied electric field on the fracture behaviors of piezoelectric *** electric boundary conditions may influence crack paths and fracture loads *** present research may be helpful for the reliability evaluation of the piezoelectric structure in the future applications.

关键词： isogeometric analysis(IGA) brittle fracture fourth-order phase-field model piezoelectric solid

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