共查询到17条相似文献,搜索用时 15 毫秒
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水电工程堆石料爆破级配要求高、块度预测难,以岩体原生节理统计和爆破裂纹模拟为切入点,采用现场调查、室内试验、数值仿真和工程检验等方式,开展堆石料爆破块度分布研究,尝试建立一套堆石料爆破块度预测方法。通过现场调查,绘制研究区域的天然节理分布网络图,建立基于原生节理统计的三维节理岩体模型;通过SHPB试验装置获取岩石在冲击荷载作用下的动力学参数,利用Ansys/Ls-Dyna模拟了爆破裂纹的扩展范围;综合原生节理调查信息和爆破裂纹模拟成果,建立调查区域爆后三维节理岩体模型;利用ANSYS输出模型所有岩块的线–面–体数据并编制Matlab块度计算程序,采用基于爆破岩块第5条最长边的块度预测指标,得到调查岩体的预测级配曲线。工程应用表明,综合考虑原生节理和爆破次生裂纹联合切割作用的堆石料级配预测方法基本符合工程实际,且基于爆破岩块第5条最长边指标的级配预测结果要优于等体积球直径指标的级配预测结果,其在江咀料场级配预测中的整体误差为5.5%。研究可为类似工程的堆石料爆破开采提供可借鉴的级配预测手段。 相似文献
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针对混凝土质量提出运用层次分析法,分析影响混凝土质量的各种因素,建立实用有效的层次结构模型,并列表采用求根法进行计算,经过一系列的综合分析和一致性检验,最终确定混凝土进行质量控制的重点,为混凝土进行质量控制提供了理论依据和指导。 相似文献
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通过对重庆—长沙高速公路井岗河特大桥T梁预应力施工研究,探讨了后张法预应力施工相关技术及质量控制,指出在后张法预应力施工过程中,确定预应力筋的强拉控制应力是施工的关键,预应力筋张拉时采用张拉应力和伸长量双控能有效控制T梁的张拉质量。 相似文献
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为研究文山州森林火灾分布特征,选取2012-2019年文山州森林火灾数据,采用ArcGIS的缓冲区分析与叠加分析方法探究居民点、道路、水系、GDP与森林火灾的关系,绘制火点分布图,建立居民点缓冲区Ⅰ、Ⅱ、Ⅲ区,道路缓冲区Ⅰ、Ⅱ、Ⅲ区,水系缓冲区Ⅰ、Ⅱ、Ⅲ、Ⅳ区,和4个GDP缓冲区,剖析云南省文山州森林火灾分布特征。结果表明:文山州道路缓冲区Ⅱ区、居民点缓冲区Ⅱ区、水系缓冲区Ⅲ区、GDP缓冲区Ⅰ区发生森林火灾的次数最多,火灾风险等级最高;2012-2015年和2016-2019年森林火灾次数在居民点、道路和水系缓冲区内均服从正态分布,道路、居民缓冲区Ⅱ区森林火灾次数分别占60.28%、62.30%,53.73%、59.01%,缓冲区Ⅰ、Ⅲ区均在28%以下;水系缓冲区Ⅲ区分别占37.85%、39.34%,其他区域呈阶梯式下降,2012-2015年文山州水系缓冲区林火次数Ⅱ区>Ⅳ区>Ⅰ区,2016-2019年Ⅳ区>Ⅱ区>Ⅰ区。2012-2019年平均火灾下降率排序为GDP缓冲区>水系缓冲区>居民点缓冲区>道路缓冲区。GDP缓冲区Ⅱ区、居民点缓冲区Ⅲ区、水系缓冲区Ⅰ区森林火灾数量下降率最高,分别是89.74%、83.67%、80%。因此,森林火灾防控管理优先级为道路缓冲区>居民点缓冲区>水系缓冲区>GDP缓冲区;可优先考虑道路缓冲区Ⅱ区、居民点缓冲区Ⅱ区、水系缓冲区Ⅲ区、GDP缓冲区Ⅰ区的森林火灾防控。研究可为文山州及云南省森林火灾防范提供技术支持。 相似文献
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Ángel Perni José Martínez‐Paz Federico Martínez‐Carrasco 《Water and Environment Journal》2012,26(2):274-284
The Water Framework Directive (WFD) aims at improving the ecological status of the water bodies in Europe. In this context, some rivers are currently being restored and, in accordance with this Directive, the restoration actions have to be evaluated from a socio‐economic approach. This work applies the Choice Modelling method to the WFD provisions for river restoration. This method proves to be useful for the economic valuation of the restoration measures, as well as a very important tool for people's public participation. In this sense, the water quality improvement has been defined as a priority action from a social point of view. Moreover, the method used has provided answers to both basic questions included in the WFD: the calculation of the economic value of the Segura River's ecological flow, the decrease of which would pose an environmental cost, and the estimation of the environmental income generated by this river. 相似文献
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Low and negative pressure events in drinking water distribution systems have the potential to result in intrusion of pathogenic microorganisms if an external source of contamination is present (e.g., nearby leaking sewer main) and there is a pathway for contaminant entry (e.g., leaks in drinking water main). While the public health risk associated with such events is not well understood, quantitative microbial risk assessment can be used to estimate such risk. A conceptual model is provided and the state of knowledge, current assumptions, and challenges associated with the conceptual model parameters are presented. This review provides a characterization of the causes, magnitudes, durations and frequencies of low/negative pressure events; pathways for pathogen entry; pathogen occurrence in external sources of contamination; volumes of water that may enter through the different pathways; fate and transport of pathogens from the pathways of entry to customer taps; pathogen exposure to populations consuming the drinking water; and risk associated with pathogen exposure. 相似文献
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With fast economic growth, industrial water pollution has been a serious problem ubiquitously in China. More threatening is that lots of economic developing regions still strategically depend on fast industrialization, neglecting the relationship between production's spatial distribution and regional water environmental carrying capacity. As a small region, Deyang City is the objective case. We propose a plant-level aggregation method to estimate the spatial distribution of industrial water pollution pressure in the future five years. Based on discrete event simulation, newly added industrial projects' sizes and location choices (refer to industrial location theory) are regionally aggregated. COD (Chemical Oxygen Demand) emission into every river reach in the region is calculated respectively. In order to recover the water environmental function, the strategy aims at controlling emission within the carrying capacity of each river reach. And the strategy is assessed on its regional effects and spatial equity, from the perspective of government and industry. The results quantitatively show the diversified uncertain bounds of river reaches' COD adoptions which will aggravate the water pollution. And the pollution control strategy's effect indicates a large different level of spatial equity for industry and government respectively. 相似文献
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全站仪自由设站隧道围岩变形非接触监测理论和方法的研究 总被引:2,自引:0,他引:2
钢尺收敛计隧道围岩变形量测由人工拉尺读数,效率低,与施工相互干扰,测量结果容易受人为因素影响。为满足现代隧道快速、大跨、安全施工需求,提出全站仪围岩变形非接触量测单站、双站自由设站三维坐标法和单站、双站独立坐标测线法的概念和方法,推导围岩变形监测全站仪自由设站坐标转换数学模型。阐述自动全站仪隧道围岩变形非接触监测系统的组成、开发及其特点。以北京东直门地铁隧道施工围岩变形监测为例,说明系统的数据处理、精度评定、图形分析和预报功能,该系统以其高精度、自动化、简便实用的优点在隧道围岩变形监测中起到重要作用。 相似文献
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Salvador Del Saz-Salazar Francesc Hernández-Sancho 《The Science of the total environment》2009,407(16):4574-4583
The Water Framework Directive (WFD) is by far the most important piece of water legislation in Europe for the coming decades. Its main aim is to achieve “good ecological status” for all water resources by 2015. The economic valuation of the non-market benefits derived from improving water quality is an important input in assisting the design and implementation of efficient and effective water management policies. In this study, the contingent valuation method has been applied with a double purpose. On the one hand, we have estimated the value of a hypothetical improvement in water quality of a river asking individuals about their willingness to pay, and on the other hand, the issue of exemptions contemplated in the WFD has been addressed surveying people on their willingness to accept compensation if projected improvements were not carried out. Finally, a comparison of costs and benefits in a cost-benefit framework shows that the net present value of the water quality policy is positive both if we consider willingness to pay estimates as willingness to accept estimates, therefore this policy appears desirable from a social perspective. 相似文献
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正式加入《华盛顿协议》标志着我国工程教育认证体系得到国际社会认可、基本实现国际实质等效,工程教育认证工作进入新发展阶段。高等工程教育质量的复杂性决定了高等工程教育质量治理必然具有丰富的理论和实践内涵。后《华盛顿协议》时代,我国开展高等工程教育质量治理具有体系、法律和制度的优势,存在先天治理能力不足、国际化水平不高、科学化程度较低的劣势,迎来高等工程教育发展的新时代和新愿景,面临整合国际规则规范、周期资格审查的挑战。我国亟需系统构建治理目标、治理主体、治理客体、治理路径,探索具有中国特色的高等工程教育质量治理模式,为深度参与全球高等工程教育治理奠定基础。 相似文献
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保护城市水域景观,并加强其开发利用已经成为现代城市建设的一个重要组成部分。尝试从居民意愿的角度出发,以开封水域景观保护和开发利用为研究对象,通过实地走访和问卷调查,分析了开封居民对开封水域景观特色、保护和开发的认知和态度。基于此,提出开封水域景观保护和开发利用的意见和建议,以期为城市水域的可持续利用提供一定的理论依据和决策方法。 相似文献
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【目的】面对长三角一体化地区生态高质量修复与智能化监测的更高诉求,开展基于深度学习的水体生境质量评价,旨在探索风景园林数字技术的前沿领域,为长三角一体化地区的水体生态修复与生态绿色发展提供信息化与智能化的技术支撑。【方法】采用基于深度学习的图像分类方法,通过卷积神经网络(convolutional neural networks, CNN)训练,实现大范围、大批量的水体生境卫星图像智能识别、分类与评价。【结果】构建了长三角一体化先行启动区水体生境卫星图像数据集,训练了水体生境质量评价深度学习模型,对研究范围内全域的水体生境进行了高精度、自动化的生境质量评价。【结论】深度学习模型能够长时序、大范围地对水体生境进行质量评价,为水体生境的修复实践提供技术支撑,未来可实现对长三角一体化示范区水体生境质量的跟踪监测。 相似文献
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本文以乾隆《京城全图》为依托,讨论了明代至民国时期合院式住宅在京城的使用与流布情况。指出明代朱元璋制定的适用于大官人之“样房”可以看作后世标准合院的先导,它强调了与廊院相关的一正两副型院落的官宅身份,并促成这种院落获得了较大的流布空间;乾隆时期京城一正两副型住宅的采用是有限的,而标准合院更少;民国时期,由于社会的错动以及北京人口的增长,不但造成一正两副型住宅数量的增加以及合院的“平民化”,并且连曾经十分少见的抄手游廊也成了所谓北京“典型民居”的必配要件。 相似文献
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以广州市荔枝湾涌、东濠涌整治工程为例,从城市更新的角度探讨大事件促成的旧城中心区水系整治所面临的种种问题及措施.先简要分析当前中国城市更新和旧城中心区水系整治的关系和主要特点,继而介绍广州市2项重点工程的主要内容.在此基础上从更新目标与效果差异、利益格局多元博弈、管理机制内在失谐、更新发展难以持续4个方面分析其中的冲突,并思考整治方法的不足.最后提出旧城中心区水系整治是历史文化生态综合廊道的建设,另外也需注意社会经济和管理制度2个方面的重要作用. 相似文献