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高速铁路桥梁段振动加速度衰减变化及频谱特征分析

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铁路节能环保与安全卫生 2024年第1期14卷 14-18,60页

作者：张维成中铁第五勘察设计院集团有限公司环境与航务工程设计研究院北京102600

通过现场监测研究了高速铁路桥梁段以墩台为中心60 m范围监测点振动加速度的衰减变化及其频谱特征。各测点处列车运行荷载引起的地面竖向加速度响应以振源为中心随距离增大整体呈现衰减趋势,但在20~30 m处出现局部放大的现象,25 m处的Z... 详细信息

通过现场监测研究了高速铁路桥梁段以墩台为中心60 m范围监测点振动加速度的衰减变化及其频谱特征。各测点处列车运行荷载引起的地面竖向加速度响应以振源为中心随距离增大整体呈现衰减趋势,但在20~30 m处出现局部放大的现象,25 m处的Z振级相当于5~10 m处的振级。竖向1/3倍频程振级中桥梁墩台振源处达到了90 dB左右,随着距离的增加,高频振动呈现较快衰减,低频振动衰减缓慢、传播更远。1/3倍频程速度有效值除振源点外,其他测点能满足精密仪器对振动速度有效值12.5μm/s的限值要求,5~40 m的振动加速度有效值在各频段较为接近,50~60 m处低频段振动显著减弱。振动加速度局部放大段应重视高速列车运行对精密仪器生产厂区等的持续性影响。

关键词：高速铁路振动加速度频谱特征环境振动

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铁路弃土(渣)场渣顶防护体系布设

中国水土保持 2024年第6期 44-46,I0001页

作者：张维成中铁第五勘察设计院集团有限公司北京102600

以新建中卫至兰州铁路甘肃段为例,研究了弃土(渣)场水土保持措施体系布设及其防治效果。结果表明:弃土(渣)场周边截水沟及渣顶排水沟的设置能有效拦截上游降雨产生的汇流冲刷,排出渣场顶部雨水,避免雨水汇流后集中下渗产生陷穴等,在下... 详细信息

以新建中卫至兰州铁路甘肃段为例,研究了弃土(渣)场水土保持措施体系布设及其防治效果。结果表明:弃土(渣)场周边截水沟及渣顶排水沟的设置能有效拦截上游降雨产生的汇流冲刷,排出渣场顶部雨水,避免雨水汇流后集中下渗产生陷穴等,在下游坡面顶部设置挡水埂能使坡面侵蚀量减少95%以上,水土保持效果显著;渣顶平整覆土后采用“田字格”状整地,能有效降低施工初期的水土流失并为植物生长创造良好微环境,是干旱半干旱区一种极为有效的水土保持整地模式;试验筛选发现相同栽植条件下四翅滨藜(Atriplex canescens)的成活率最高,平均可达91%,且养护管理要求低,柠条(Caragana korshinskii)成活率次之,撒播草籽成活率、保存率普遍较低。

关键词：弃土(渣)场挡水埂植被恢复 “田字格”状整地中卫至兰州铁路甘肃段

Micro-annulus generation under downhole conditions: Insights from three-dimensional staged finite element analysis of cement hardening and wellbore operations

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1185-1200页

作者： weicheng zhang Andreas Eckert Department of Geosciences and Geological and Petroleum Engineering Missouri University of Science and TechnologyRollaMOUSA

A micro-annulus(MA)is defined as a high permeability zone or gap initiating/occurring at the casingcement and cement-formation interfaces during the wellbore life *** MA can significantly compromise wellbore integrity by establishing enhanced fluid flow *** study uses a staged finite element approach to simulate wellbore integrity during various loading steps of wellbore operations under downhole *** emphasis is placed on the processes of cement poro-elastic property evolution,volume variation,and pore pressure variation as part of the cement hardening *** resulting state of stress during the life cycle of a typical injection well(***,completion,and injection)is analyzed to assess the onset and evolution of micro-annuli at various interfaces of the composite wellbore system under downhole *** results show that cement shear failure is observed at the casing-cement interface during pressure testing(excessive wellbore pressure);and tensile debonding failure initiates at the cement-formation interface due to cement shrinkage during hardening and injection-related cooling(thermal cycling).Sensitivity analyses considering several parameters show that:(1)the degree of poro-elastic bulk shrinkage has significant implications for both shear and tensile failure initiation e the less the cement shrinks,the less likely the failure initiation is;(2)cement integrity increases with increasing depth;(3)cement pore pressure evolution has significant implications for tensile failure e if cement pore pressure decreases more,higher temperature differences can be sustained before an MA occurs;and(4)cement temperature fluctuations during hardening promote initiation of debonding *** summary,the results presented indicate that establishing downhole conditions to quantitatively analyze MA generation is *** results are different compared to laboratory studies without considering/simulating downhole *** kno

关键词： Micro-annulus Debonding Staged finite element analysis Cement hardening Poro-elastic bulk shrinkage Pore pressure Temperature fluctuation

Digestive perianastomotic ulcerations after intestinal resection in children

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World Journal of Pediatric Surgery 2023年第3期6卷 123-128页

作者： weicheng zhang Jinfa Tou Department of Neonatal Surgery Zhejiang University School of Medicine Children's HospitalHangzhouZhejiangChina

Digestive perianastomotic ulceration(DPAU)is a rare complication after intestinal resection and anastomosis occurring at or near the anastomosis *** purpose of this review is to summarize the characteristics of DPAU,including the etiology,diagnosis and differential diagnosis,clinical manifestations,treatment,and future *** recent literature on DPAU was searched in PubMed,Embase,and Cochrane and then *** clinical manifestations of DPAU are mainly gastrointestinal symptoms such as bloody stool and chronic *** diagnosis of DPAU is *** diseases,such as Crohn’s disease,must be ruled out before a diagnosis can be *** addition,there are no clear treatment guidelines due to the high degree of heterogeneity in response to drugs and *** is recommended to adjust medication in time and combine various treatment *** addition,the mechanism that causes DPAU is not well understood;however,several possible mechanisms have been proposed,such as scar tissue ischemia and underlying ***,there is a high risk of relapses,and a long-term follow-up is *** issues remain to be solved in this area;therefore,more randomized controlled trials and studies should be carried out to further understand this disease.

关键词： diagnosis drugs treatment

A cellular automata evacuation model considering friction and repulsion

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Science China(Technological Sciences) 2005年第4期48卷 403-413页

作者： SONG Weiguo YU Yanfei FAN weicheng zhang Heping State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230027 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230027 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230027 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230027 China

There exist interactions among pedestrians and between pedestrian and environment in evacuation. These interactions include attraction, repulsion and friction that play key roles in human evacuation behaviors, speed and efficiency. Most former evacuation models focus on the attraction force, while repulsion and friction are not well modeled. As a kind of multi-particle self-driven model, the social force model introduced in recent years can represent those three forces but with low simulation efficiency because it is a continuous model with complex rules. Discrete models such as the cellular automata model and the lattice gas model have simple rules and high simulation efficiency, but are not quite suitable for interactions’ simulation. In this paper, a new cellular automata model based on traditional models is introduced in which repulsion and friction are modeled quantitatively. It is indicated that the model can simulate some basic behaviors, e.g. arching and the “faster-is-slower” phenomenon, in evacuation as multi-particle self-driven models, but with high efficiency as the normal cellular automata model and the lattice gas model.

关键词： evacuation, cellular automata, multi-particle self-driven model, lattice gas.

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企业内部生产单元层级环境风险事故模拟模型

环境监控与预警 2024年第3期16卷 37-42,48页

作者：张炜程杨瑞雯刘苗苗江苏金融租赁股份有限公司江苏南京210041 污染控制与资源化研究国家重点实验室南京大学环境学院江苏南京210023

生产单元是企业内部环境风险防控的最小节点。生产企业内部存在风险节点数量繁多、属性差异大且互相存在联级放大效应等问题,使得企业环境风险一直存在较大的不确定性,给企业环境风险事故源头防控带来很大困难。传统的企业环境风险量化... 详细信息

生产单元是企业内部环境风险防控的最小节点。生产企业内部存在风险节点数量繁多、属性差异大且互相存在联级放大效应等问题,使得企业环境风险一直存在较大的不确定性,给企业环境风险事故源头防控带来很大困难。传统的企业环境风险量化评估方法侧重整体的环境风险评估,精细度不足,缺乏对生产单元间相互影响等复杂情况的考量,评估结果准确性较低,且评估成本高、效率低。针对企业内部生产单元层级事故风险难以厘清的问题,梳理了上万条环境风险重点关注行业的历史环境事故,创新性地构建了考量“群发/链发”情况的事故情景与概率矩阵;考量企业生产单元与风险物质复杂属性、事故情景特性、周边扩散条件、环境风险受体等多维因素,集成设计了一套企业环境风险事故全过程模拟模型。通过从事故情景构建到事故损害结果分析的全链路自动化模拟,实现对企业生产单元环境风险的量化评估,达到精准识别企业内高风险节点,提升企业风险防控能力的目的;最后,研究通过对比真实历史环境事故调查结果,验证模型模拟具有较高准确性。

关键词：企业环境风险生产单元环境风险事故模拟模型 “群发/链发”环境事故

Dynamic nano-Ag colloids cytotoxicity to and accumulation by Escherichia coli:Effects of Fe^3+,ionic strength and humic acid

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Journal of Environmental Sciences 2020年第3期32卷 180-193页

作者： weicheng zhang Bingyu Ning Caiyun Sun Ke Song Xin Xu Tao Fang Lunguang Yao Collaborative Innovation Center of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province Nanyang Normal UniversityNanyang 473061China Henan Key Laboratory of Ecological Security for Water Source Region of Mid-line of South-to-North Diversion Project Nanyang Normal UniversityNanyang 473061China State Key Laboratory of Motor Vehicle Biofuel Technology Nanyang 473000China Institute of Hydrobiology Chinese Academy of SciencesWuhan 430072China University of Chinese Academy of Sciences Beijing 100049China

Released Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials,and thus,the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag+ *** recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays,and shifts to both Ag particles and released Ag^+ in 48 hr ***,as a continued study,the cytotoxicity and accumulation of 50 and 100 nm Ag colloids in Escherichia coli were determined *** cytotoxicity and mechanisms of nanoAg colloids are dynamic throughout exposure and are derived from both Ag ions and *** accumulation by *** is derived mainly from extracellular Ag particles during the initial 12 hr of exposure,and thereafter mainly from intracellular Ag ***^3+ accelerates the oxidative dissolution of nano-Ag colloids,which results In decreasing amounts of Ag particles and particle-related ***^+ stabilizes nano-Ag colloids,thereby decreasing the bioavailability of Ag particles and particle-related *** acid(HA) binds Ag^+ to form Ag^+-HA,decreasing ion-related toxicity and binding to the *** surface,decreasing particle-related *** in complex conditions showed a stronger relative contribution to toxicity and accumulation than Na^+ or Fe^3+.The results highlighted the cytotoxicity and mechanism of nano-Ag colloids are dynamic and affected by environmental factors,and therefore exposure duration and water chemistry should be seriously considered in environmental and health risk assessments.

关键词： Cytotoxicity mechanism Accumulation Nano-Ag colloids Escherichia coli Environmental factors

Numerical estimates of the maximum sustainable pore pressure in anticline formations using the tensor based concept of pore pressure-stress coupling

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第1期7卷 60-72页

作者： Andreas Eckert weicheng zhang Xiaolong Liu Matthew Paradeis Department of Geosciences and Geological and Petroleum Engineering Missouri University of Science and Technology

The advanced tensor based concept of pore pressure-stress coupling is used to provide pre-injection analytical estimates of the maximum sustainable pore pressure change, ΔPc, for fluid injection scenarios into generic anticline geometries. The heterogeneous stress distribution for different prevailing stress regimes in combination with the Young's modulus(E) contrast between the injection layer and the cap rock and the interbedding friction coefficient, m, may result in large spatial and directional differences of ΔP c. A single value characterizing the cap rock as for horizontal layered injection scenarios is not obtained. It is observed that a higher Young's modulus in the cap rock and/or a weak mechanical coupling between layers amplifies the maximum and minimum ΔPc values in the valley and limb,respectively. These differences in ΔPc imposed by E and m are further ampli fied by different stress regimes. The more compressional the stress regime is, the larger the differences between the maximum and minimum ΔPc values become. The results of this study show that, in general compressional stress regimes yield the largest magnitudes of ΔPc and extensional stress regimes provide the lowest values of ΔPc for anticline formations. Yet this conclusion has to be considered with care when folded anticline layers are characterized by flexural slip and the friction coefficient between layers is low, i.e.μ=0.1. For such cases of weak mechanical coupling, ΔPc magnitudes may range from 0 MPa to 27 MPa, indicating imminent risk of fault reactivation in the cap rock.

关键词： Pore pressure-stress coupling Anticlines Stress regimes Friction coefficient

Numerical estimates of the maximum sustainable pore pressure inanticline formations using the tensor based concept of porepressure-stress coupling

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岩石力学与工程学报 2015年第1期34卷 60-72页

作者： Andreas Eckert weicheng zhang Xiaolong Liu Matthew Paradeis Department of Geosciences and Geological and Petroleum Engineering Missouri University of Science and Technology Rolla MO USA

关键词： Pore pressureestress coupling Anticlines Stress regimes Friction coefficient