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Journal of Civil Engineering and Architecture 2024年第2期18卷 51-59页

作者： Yasushi Uematsu Kazuya Takahashi New Industry Creation Hatchery Center Tohoku UniversitySendai 980-8579Japan Engineering Headquarters Shimizu CorporationChuo-kuTokyo 104-8370Japan

The present paper first investigates the collapse behavior of a conventional pipe-framed greenhouse under snow loading based on a 3-D finite element analysis,in which both geometrical and material non-linearities are *** snow load distribution patterns related to the wind-driven snow particle movement are used in the *** is found that snow load distribution affects the deformation and collapse behavior of the pipe-framed greenhouse *** results obtained in this study are consistent with the actual damage ***,discussion is made of the effects of reinforcements by adding members to the basic frame on the strength of the whole structure,in which seven kinds of reinforcement methods are examined.A buckling analysis is also carried *** results indicate that the most effective reinforcement method depends on the snow load distribution pattern.

关键词： Pipe-framed greenhouse snow loading collapse buckling finite element analysis

Experimental and numerical investigations of the collapse of a laser-induced cavitation bubble near a solid wall

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Journal of Hydrodynamics 2022年第2期34卷 189-199页

作者： Jia-yun Zhang Yu-xin Du Jia-qi Liu Yu-rong Sun Zhi-feng Yao Qiang Zhong College of Water Resources and Civil Engineering China Agricultural UniversityBeijing100083China Beijing Water Supply Network System Safety and Energy Saving Engineering Technology China Agricultural UniversityBeijing100083China

With the collapse of cavitation bubbles near the wall,micro-jets and shock waves will be formed,to generate a high-pressure load and to cause the cavitation damage on the surface of the hydraulic *** to the rapid development of the cavitation bubble collapse process(in the time scale of hundred nanoseconds),the time resolution of the conventional high-speed cameras should reach more than one million frames per second,which will limit the spatial resolution,and obscure the details of the cavitation bubble shape near the cavitation bubble collapse *** this paper,with the help of the laser cavitation bubble photogrammetry system with nanosecond-micron space-time resolution,the experiment is carried out for the cavitation bubble collapse morphology evolution near the *** morphological characteristics of the cavitation bubble collapse at specific times are *** the help of the OpenFOAM code,the collapse process of the cavitation bubble near the solid wall is *** is shown that the cavitation bubble near the wall collapses in an axial symmetric heart shape and the micro-jet directed to the wall will pull the cavitation bubble towards the *** counter-jet generated in the rebound stage will drive the cavitation bubble to move away from the *** numerical simulation of the cavitation bubble shape in the collapse period is well consistent with the experimental results,but the ability to capture the shock wavefront needs to be *** the conditions studied in this paper,the cavitation bubble collapse micro-jet velocity can reach up to a hundred meters per second both in the experiment and the numerical simulation.

关键词： Near wall cavitation collapse micro-jet shock wave

Experimental and Numerical Study on Progressive collapse Analysis of a Glulam Frame Structure:*** Column Exposed to Fire

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Journal of Renewable Materials 2023年第2期11卷 905-920页

作者： Xiaowu Cheng Xinyan Tao Lu Wang College of Civil Engineering Nanjing Tech UniversityNanjing211816China

This paper presents experimental and numerical investigations on progressive collapse behavior of a two-story glulam frame when the side column is exposed to ISO834 standard *** collapse mechanism initiated by fire is *** experimental results show that the progressive collapse of a glulam frame could be described for three stages,namely bending effect stage,catenary effect stage and failure stage,*** stages are discussed in detail to understand the structural behavior before and during *** is demonstrated that the entire frame slopes towards the side of the heated column,and the“overturning”collapse occurs *** catenary effect of beams is the main reason for the progressive collapse of the *** addition,a finite element model of a glulam frame is established to simulate the progressive collapse *** effects of axial loads on the columns are *** numerical simulation results agree well with the experimental results,which could verify the effectiveness and practicability of finite element ***,the progressive collapse resistance of the frame in practical design were proposed.

关键词： collapse glulam frame structure fire failure mechanisms

Ubiquitin homeostasis disruption, a common cause of proteostasis collapse in amyotrophic lateral sclerosis?

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Neural Regeneration Research 2022年第10期17卷 2218-2220页

作者： Christen G.Chisholm Jeremy S.Lum Natalie E.Farrawell Justin J.Yerbury Illawarra Health and Medical Research Institute/Molecular Horizons and School of Chemistry and Molecular Bioscience Science Medicine and Health FacultyUniversity of WollongongNorthfields AveWollongongNSWAustralia

Amyotrophic lateral sclerosis(ALS)is associated with proteostasis collapse:ALS is an unrelenting neurodegenerative disease that is characterized by the loss of motor neurons in the brain and spinal cord,resulting in the progressive atrophy,and eventual paralysis,of skeletal *** due to respiratory failure usually occurs within 2-5 years from symptom *** 90%of ALS cases are of unknown etiology and are termed sporadic ALS(sALS).The remaining 10%of ALS cases present with a family history(familial ALS;fALS)and are associated with genetic mutations in a range of over 20 functionally heterogeneous *** of disease origin,the pathological hallmark of ALS is the accumulation of ubiquitylated protein inclusions in motor neurons and surrounding glial *** presence of these inclusions,compromised largely of misfolded and aggregated proteins,implies a collapse in *** refers to the maintenance of the proteome in a state of balance or equilibrium so that a cell can perform its proper function.

关键词： stasis homeostasis collapse

collapse arrest in the space-fractional Schrodinger equation with an optical lattice

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Chinese Physics B 2021年第10期30卷 328-333页

作者： Manna Chen Hongcheng Wang Hai Ye Xiaoyuan Huang Ye Liu Sumei Hu Wei Hu School of Electrical Engineering and Intelligentization Dongguan University of TechnologyDongguan 523808China Department of Physics Guangdong University of Petrochemical TechnologyMaoming 525000China Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices South China Normal UniversityGuangzhou 510006China

The soliton solution and collapse arrest are investigated in the one-dimensional space-fractional Schrodinger equation with Kerr nonlinearity and optical *** approximate analytical soliton solutions are obtained based on the variational approach,which provides reasonable ***-stability analysis shows that all the solitons are linearly *** collapses are found when the Levy index 1collapse is arrested by the lattice potential when the amplitude of perturbations is small *** is numerically proved that the energy criterion of collapse suppression in the two-dimensional traditional Schrodinger equation still holds in the one-dimensional fractional Schr odinger *** physical mechanism for collapse prohibition is also given.

关键词： soliton solution collapse variational approach nonlinear Schrodinger equation

collapse period of degrading SDOF systems

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Earthquake Engineering and Engineering Vibration 2014年第4期13卷 681-694页

作者： Borekci M Kircil MS Ekiz I Yildiz Technical University

Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. Many researchers proposed simplified methods to estimate the demand of a structure under strong ground motions. However, most of them did not consider degradation and collapse potential of the structures. Even some of theme considered the degradation effect, stiffness and strength degradation effects were considered separately without collapse potential caused by dynamic instability. In this study, collapse potential of SDOF systems caused by dynamic instability with stiffness and strength degradation has been investigated. Nonlinear time history analyses were performed, using an energy-based, strength and stiffness degraded hysteretic model that considers the collapse potential, with 160 earthquake acceleration time histories. An equation was proposed for the estimation of collapse period of SDOF systems as a function of certain strength reduction factor, ductility level and post-capping stiffness ratio. Finally, effects of parameters of the considered hysteretic model and local site conditions on the collapse period were investigated.

关键词： collapse degradation dynamic instability hysteretic types,earthquake

collapse of a Deep Excavated Foundation Pit in the Soft Soils by 3-D FEM

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 162-174页

作者： ZHUANG Haiyang XUE Xuchao YU Xu Institute of Geotechnical Engineering Shandong University Institute of Geotechnical Engineering Nanjing Tech University School of Architecture Engineering Nanjing Institute of Technology

In view of the collapse of a deep excavated foundation pit of the Xianghu subway underground station in Hangzhou of China,the main features of the accident are analyzed,and the induced factors of the accident are summarized. Then,a 3-D FEM analysis model is created to demonstrate the soil-support structures interaction system,and the effect of the main factors,such as the volume replacement ratio of the bottom soil reinforcing,the asymmetric ground overload,the embedded depth of the diaphragm wall,the shear strength of the bottom soils disturbed by the construction,and the excessive excavation of the bottom soil,are analyzed and compared. The results show that the ineffective original reinforcement plan for the bottom soft soil is the most prominent factor for the accident,and the disturbance effect of the deep excavation on the shear strength of the bottom soft soil is another significant factor for the accident. Meanwhile,if the reinforcement of the bottom soft soil is canceled,an appropriate extension of the diaphragm retaining walls to the under lying harder soil layer can also effectively prevent the collapse of the deep excavated foundation pit. In addition,the partly excessive excavation in the process has a great influence on the axial force of the most nearby horizontal support but few effect on the stability of the diaphragm wall. Thus,the excessive excavation of the bottom soils should not be the direct inducing factor for the accident. To the asymmetric ground overload,it should be the main factor inducing the different damage conditions of the diaphragm walls on different sides. According to the numerical modeling and actual engineering accident condition,the development process of the accident is also identified.

关键词： deep excavation subway station collapse process numerical modeling soft soil

collapse behavior and microstructural evolution of loess soils from the Loess Plateau of China

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Journal of Mountain Science 2018年第8期15卷 1642-1657页

作者： XIE Wan-li LI Ping ZHANG Mao-sheng CHENG Tian-e WANG Yong State Key Laboratory of Continental Dynamics Northwest University Department of Geology Northwest University Key Laboratory for Geo-hazard in Loess Area Ministry of Land and ResourcesXi'an Center of China Geological Survey College of Urban and Environmental Sciences School of Foreign Languages Northwest University

Loess soils are characterized by metastable microstructure, high porosity and water-sensitivity. These soils have always been problematic soils and attracted attention from researchers all over the world. In the present study, three loess soils extracted at various depths from the Loess Plateau of China, i.e. Malan(Q_3), upper Lishi(Q_2~2) and lower Lishi(Q_2~1) loess soils, were studied. Single oedometer-collapse tests were performed on intact loess specimens to investigate the collapse behavior of three loess soils. The microstructure and chemical composition of each loess before and after collapse test were characterized using scanning electron microscopy(i.e. SEM) and energy dispersive spectroscopy(i.e. EDS) techniques. The microstructural evolution due to wetting collapse was interpreted qualitatively and quantitatively in terms of the pore morphology properties. The results suggest that:(1) the collapse potential of each loess may rise again after a round of rise and drop, which could be failure of the new-developed stable structure under quite high vertical pressure. It implies that loess may collapse even if it has collapsed.(2) Q_3, Q_2~2 and Q_2~1 loess have different types of microstructure, namely, granule, aggregate and matrix type of microstructure, respectively.(3) The microstructural evolution due to loading and wetting is observed from a granule type to an aggregate type and finally to a matrix type of structure. The variations in distributions of pore morphology properties indicate that collapse leads to a transformation of large-sized pores into small-sized pores, re-orientation and remolding of soil pores due to particle rearrangement.(4) A porous structure is essential for loess collapse; however, the non-water-stability of bonding agents promotes the occurrence of collapse under the coupling effect of loading and wetting.

关键词： Loess collapse Microstructure Scanning electron microscopy Image processing Pore morphology properties

Excavation collapse of Hangzhou subway station in soft clay and numerical investigation based on orthogonal experiment method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第10期13卷 760-767页

作者： Xiao-nan GONG Xue-chan ZHANG MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310058China Institute of Geotechnical Engineering Zhejiang UniversityHangzhou 310058China

This paper studies the excavation collapse at the Xianghu subway station on Hangzhou metro line *** objective is to present an overview of this case study and discuss the cause of the *** field investigation and preliminary analysis,the reasons for the excavation collapse were the misuse of the soil parameters,over excavation,incorrect installation of steel struts,invalid monitoring data,and inadequate ground ***,a small strain constitutive model was used for further *** order to estimate damage efficiently,the orthogonal array(OA) was introduced for screening the key factor in the numerical *** estimated indexes including deformations and internal forces of the excavation were taken,and the effectiveness of four factors which may cause the collapse was *** numerical experiments and interaction analysis,it is found that the deformation and internal force can be well controlled by jet grouting of the subsoil under the final cutting surface,but increasing the improvement ratio of the jet grouting cannot help optimize the excavation behavior efficiently,and without jet grouting and the fourth level struts,the deformation and internal force of the excavation in this case will far surpass the allowable value.

关键词： collapse Case study Numerical analysis Orthogonal experiment method Interaction

Analysis of collapse in Flattening a Micro-grooved Heat Pipe by Lateral Compression

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Chinese Journal of Mechanical Engineering 2012年第6期25卷 1210-1217页

作者： LI Yong HE Ting ZENG Zhixin School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510640China

The collapse of thin-walled micro-grooved heat pipes is a common phenomenon in the tube flattening process, which seriously influences the heat transfer performance and appearance of heat pipe. At present, there is no other better method to solve this problem. A new method by heating the heat pipe is proposed to eliminate the collapse during the flattening process. The effectiveness of the proposed method is investigated through a theoretical model, a finite element（FE） analysis, and experimental method. Firstly, A theoretical model based on a deformation model of six plastic hinges and the Antoine equation of the working fluid is established to analyze the collapse of thin walls at different temperatures. Then, the FE simulation and experiments of flattening process at different temperatures are carried out and compared with theoretical model. Finally, the FE model is followed to study the loads of the plates at different temperatures and heights of flattened heat pipes. The results of the theoretical model conform to those of the FE simulation and experiments in the flattened zone. The collapse occurs at room temperature. As the temperature increases, the collapse decreases and finally disappears at approximately 130 ℃ for various heights of flattened heat pipes. The loads of the moving plate increase as the temperature increases. Thus, the reasonable temperature for eliminating the collapse and reducing the load is approximately 130℃. The advantage of the proposed method is that the collapse is reduced or eliminated by means of the thermal deformation characteristic of heat pipe itself instead of by external support. As a result, the heat transfer efficiency of heat pipe is raised.

关键词： tube flattening collapse micro-grooved heat pipe heating lateral compression FE simulation