预制沟槽对爆破震动阻隔效应的实验研究

由于裂隙或者沟槽对炸药爆炸引起的震动具有良好的隔震作用,所以用现场试验的方法对比研究了用导爆索爆炸形成减震沟槽和人工开挖沟槽的减震效果。用3发50 g TNT当量、1m埋深的爆炸实验,研究了爆破成形和人工开挖预制的两种沟槽的隔震效果。实验结果表明,在爆破成形沟槽的两边存在一定宽度的裂隙区。两种沟槽均有效地降低了爆破震动的幅度并改变了地震波的频谱,而爆破成形沟槽的减震效果优于人工开挖的。离减震沟槽越近,隔震效果越明显。减震沟槽对中远区地震波低频部分隔震效果明显。     

Effect of deicing solutions on the tensile strength of micro- or nano-modified asphalt mixture

This paper reports on the potential benefits of micro- or nano-sized materials for asphalt mixtures used on pavements, specifically when they are exposed to water or deicing solutions. Asphalt mixtures were prepared with various amount of nanoclay and/or carbon microfiber, and compacted using the Superpave? gyratory compactor. Moisture susceptibility and deicer impacts were assessed by exposing the samples to water or deicing chemicals (NaCl, MgCl₂ and CaCl₂), and seven freeze–thaw cycles, in a modified AASHTO T283 test. Comparisons of micro- or nano-modified asphalt mixtures exposed to deicers are made based on results of indirect tensile strength tests, which preliminarily demonstrate the great potential of using microfibers and nanoclays in asphalt mixture for improved performance. Based on the results, it was found that the addition of nanoclay and carbon microfiber would improve a mixture’s moisture susceptibility performance or decrease the moisture damage potential in most cases. The detailed effects of deicing solutions on the tensile strength of micro- or nano- modified asphalt mixture are discussed in this paper.     

建筑史学的危机与争辩

本文是对2017年两次小型建筑史会议上出现的有关建筑史学思想的一些争论,以及大家共同意识到的当下建筑史学所面临的危机进行的辨析。论文讨论了建筑史学研究方法论上的通史与案例研究问题,分析了建筑史学思想的现代性与后现代性问题,关注了建筑史应当关注历史还是关注当下的问题,也讨论了建筑史学作为一门学问,究竟是有用还是无用的问题。论文希望对当前社会对建筑史学科存在的一些不同的看法,或建筑史界本身对于自己学科的一些不同观点,加以讨论与厘清。     

水质模糊聚类及环境同位素在探测某堤基渗漏通道中的应用

利用环境同位素及地下水水质的分析 ,结合地质条件 ,对调查堤坝渗漏具有很重要的意义。在许多情况下 ,对孔或泉水的水化学和同位素成分分析可探测已存在的集中渗漏通道。文中以某堤段堤内管涌为例 ,以钻孔及江水水样的水质及同位素成分为研究对象 ,以模糊数学为工具 ,分析了堤后管涌的成因 ,对下一步采取工程措施具有科学的指导意义。     

Integrating Water Management and Spatial Planning

A close connection is emerging between water management and spatial planning in the Netherlands as a result of a new acceptance of water on land, and the European Union's recent emphasis on managing water at the scale of entire river basins. We review Dutch and European trends in water management and identify four potential approaches to integrating water management and spatial planning in the Netherlands or elsewhere, depending on whether we adopt a regulatory or more strategic approach to planning, and whether we make water policy for areas defined by their water related functions (like watersheds or coastlines) or incorporate water issues into policy for broader socio cultural regions.     

松软土地区高速铁路路涵过渡段动静态试验研究

为评价松软土地区高速铁路路涵过渡段采用倒梯形级配碎石并掺水泥处理方法的适宜性,采用弦式和电阻式土压力计测试过渡段在施工期及联调联试期CFG桩顶和桩间静土压力、基床底层表面及该位置以下50cm处的动土压力变化特征。结果表明:离涵洞中心不同位置的桩顶和桩间土压力,随施工荷载的变化而变化,且桩顶土压力对加载变化更加敏感;过渡段的动应力在纵向上表现为"W"形,其最大值出现在距涵洞中心10m位置处。     

Unintentional landscapes

The presence of ‘unintentional landscapes’ invites reflection on the difficulties in defining marginal or interstitial spaces, or indeed the concept of landscape itself. In some cases, so-called wastelands or terrain vague have been appropriated as spaces of adventure, creativity or discovery. In other cases, these anomalous spaces have been the focus of anxiety or disdain, or simply erased on account of their putative ‘emptiness’ to make way for more lucrative forms of land use. In recent years, however, fragments of spontaneous nature have been incorporated into landscape design, or even mimicked through the adoption of a ‘wasteland aesthetic’. Marginal spaces appear to transcend existing Eurocentric circuits of landscape discourse by offering multiple meanings and manifestations. Indeed, the cultural and scientific interest in these spaces lies precisely in their complexity and uncertainty.     

煤岩动力灾害电磁辐射预测技术中力电耦合方法的研究及应用

对煤岩动力灾害电磁辐射预测技术的研究现状和发展趋势进行了论述与分析,基于煤岩变形破裂电磁辐射信号与受载时应力变化之间的关系,从FLAC应力场数值模拟与电磁辐射传播的角度对煤岩变形破裂电磁辐射力电耦合研究方法进行了研究。研究结果表明:基于FLAC模拟的力电耦合方法能合理地确定应力集中区域以及正确模拟电磁辐射在煤岩层内的分布规律,该方法为现场应用电磁辐射方法和技术准确预测预报煤岩灾害动力现象提供可靠的理论基础,对于完善煤岩变形破裂电磁辐射监测和检测理论以及促进相关学科的发展具有理论和现实意义。最后还对未来煤岩动力灾害电磁辐射预测技术研究的发展前景进行展望。     

Openings in Thin-Walled steel structures

A review is made of the research work that has been carried out to date to account for the effects of openings on the behaviour of thin-walled elements in steel structures. Attention is directed to relatively thin steel plate elements typical of those that occur in plated structures. Plate elements that are subjected to uniaxial compression or biaxial compression or shear loading, stiffened plates, shear webs and cold formed steel sections are considered separately. Analytical and experimental work carried out on centrally or eccentrically placed, reinforced or unreinforced circular or rectangular openings are considered in the review. Design methods of thin-walled steel structural elements that account for the presence of openings are highlighted.     

Predicting the Behavior of Predevelopment Landowners on the Urban Fringe

If the planner had a simple predictive technique to assess the likelihood that a parcel in nonurban use on the urban fringe would be sold during the next few years, he would be in a better position to anticipate the location of new urban fringe development. Such a model was developed from tests in two North Carolina cities, utilizing landowner and property information generally available in public records or in the planner's files. Utilizing data on how long the land had been held prior to the start of the study period, whether or not the owner lived on the land, whether or not the owner was retired, whether the ownership was single or joint, the assessed value of the land, and the amount of urban development surrounding the parcel, the model was able to classify from 60 to 80 percent of the sample parcels correctly as being “sold” or “held” over the 10-year test period.     

燃气管网故障管段隔离决策算法

建立了燃气管网故障管段隔离决策算法,用于管段（或阀门）发生故障时,为了从管网隔离故障管段（或阀门）,确定需关闭的阀门。由该算法编制的程序计算结果可给出相应的故障管段（或阀门）隔离影响区、影响供气量等。基于该算法,利用GIS的管网数据库,可实现在线故障管段（或阀门）隔离决策。     

一种用于锚杆支护数值模拟的单元处理方法

结合三角形、四边形等实体单元的位移插值函数和一维轴力杆单元的刚度矩阵，推导出了一种用于锚杆支护数值模拟的单元列式，可以在地下结构有限元计算中的任何开挖步自由地加设或拆除锚杆，而且，不必在划分初始计算网格时，事先考虑或预留锚杆的结点位置，大大地简化了有限元的前处理或网格划分过程。     

螺栓孔径与孔型对高强度螺栓摩擦型连接承载能力影响的试验

针对钢结构工程的高强度螺栓摩擦型连接中,已经出现采用大圆孔或槽型孔的情况,对不同螺栓孔径与孔型的高强度螺栓进行预拉力损失试验和抗滑移试验,以研究分析预拉力以及抗滑移系数随着孔径、孔型变化的规律.     

Novel methods for integrated risk assessment of cumulative stressors — Results from the NoMiracle project

This special issue covers the main results of the European Sixth Framework Integrated Research project NoMiracle (Novel Methods for Risk Assessment of Cumulative stressors in Europe). New tools to analyse, characterise and quantify the combined risks to health or the environment from multiple stressors are presented or reviewed. Examples of cumulative stressors are mixtures of chemicals alone or in combination with biological or physical environmental factors such as pathogens and climate extremes. Among the main findings, the scientific work points at the importance of time in dealing with toxicity, and in particular the toxicity of chemical mixtures, the natures of the uncertainties associated with risk assessment and the value of visualisation in identifying and quantifying the most relevant risks. A major conclusion of the project is that researchers and regulators should focus on the receptor rather than on the single stressor or combination of agents. There is also a need for more efforts on mechanistic understanding and for a mechanism-based framework for interpreting mixture/multiple stressor effects.The new tools are available on the internet (http://nomiracle.jrc.ec.europa.eu).     

Combined loading of strip footings on sand-over-clay with layers of varying extents

This study describes the numerical analyses performed to investigate the bearing capacity of strip footings placed on granular (frictional) material overlying soft clay subjected to combined vertical-horizontal and vertical-moment loading. A plane-strain finite element limit analysis is used to estimate the limiting load combinations for two layer soil geometries where the top layer is either fully extended in the horizontal direction or it is of limited horizontal extent, representative of rock or gravel berms commonly used in offshore practice.Bearing capacity envelopes for combined vertical, horizontal and/or moment loading are well-documented in the literature for cases of footings resting on single sand or clay soil. For two-layer sand-over-clay soil with a horizontally extensive top layer, the vertical-horizontal and vertical-moment envelopes initially coincide with the envelope for a single sand layer at low vertical loads, but show an abrupt reduction in the horizontal or moment capacity as the vertical load increases beyond a certain critical vertical load. The critical vertical load is found to vary as a function of the thickness and the lateral extent of the upper layer. Relationships are presented to enable the vertical-horizontal and vertical-moment envelopes to be estimated based on the problem geometry and material properties.The findings in this study provide insight into the response of subsea foundations placed on rock or gravel of limited extent overlying a clay seabed as well as the general response of shallow foundations on two-layer profiles.     

螺栓孔径与孔型对高强度螺栓摩擦型连接承载能力影响的试验

针对钢结构工程的高强度螺栓摩擦型连接中,已经出现采用大圆孔或槽型孔的情况,对不同螺栓孔径与孔型的高强度螺栓进行预拉力损失试验和抗滑移试验,以研究分析预拉力以及抗滑移系数随着孔径、孔型变化的规律。     

Sensor-based demand-controlled ventilation: a review

With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation is modulated over time based on the signals from indoor air pollutant or occupancy sensors. SBDCV offers two potential advantages: better control of indoor pollutant concentrations, and lower energy use and peak energy demand. Based on theoretical considerations and on a review of literature, SBDCV has the highest potential to be cost-effective in applications with the following characteristics: (a) a single or small number of pollutants dominate so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy. At present, most SBDCV systems are based on monitoring and control of carbon dioxide (CO₂) concentrations. There is a limited number of well-documented case studies that quantify the energy savings and the cost-effectiveness of SBDCV. The case studies reviewed suggest that in appropriate applications, SBDCV produces significant energy savings with a payback period typically of a few years.     

What affects children’s outcomes: house characteristics or homeownership?

We study the impact of housing conditions on the educational outcomes of young persons in Switzerland. We focus on children aged 15–19, who are potentially enrolled in or graduates of high school or vocational training programs, and young adults aged 20–24, who are potentially students in or graduates of university or other tertiary institutions. Housing conditions are characterized in three ways: whether the parents rent or own the dwelling, the type of dwelling (house or apartment), and a measure of crowding (occupants per room). We find that the density of residents in the dwelling is the only influential housing characteristic. Crowding directly affects the outcomes of children aged 15–19 and presumably indirectly affects the outcomes of young adults given that admission to university study requires completion of high school. None of the other housing characteristics affects children’s outcomes. In particular, homeownership is not statistically significant in any of our estimations.     

Electrochemical oxidation of phenolic wastes with boron-doped diamond anodes

The electrochemical oxidation of several phenolic aqueous wastes has been studied using a bench-scale plant with a single-compartment electrochemical flow cell. Boron-doped diamond materials were used as the anode. Complete mineralization of the waste was obtained in the treatment of phenols not substituted with chlorine or nitrogen. Chlorinated phenolic compounds were transformed into carbon dioxide; volatile organochlorinated compounds and nitro-substituted phenols deal with the formation of polymeric materials. These polymeric materials behave as final products or treatment intermediates depending on the nature of the initial pollutant. The removal of nitro- or the chloro-group from the phenolic molecule seems to be one of the first stages in the treatment. Non-nitrogenated or chlorinated carboxylic acids have been found to be the main intermediates in the electrochemical oxidation of all the phenolic compounds tested. The efficiencies of the process depend strongly on the concentration of organic pollutants and on their nature, and not on the current density, at least in the operation range studied.     

On the correlation between wind speed,coarse aerosol concentration and the electrical state in the ground atmospheric layer in semi-arid areas

Our general work has been dedicated to the problems connected with the influence of short-term changes of the atmospheric state on some medically unexplained human responses. What are the meteorological stimuli eliciting the transition between health and disease? There are many reports on the impact of humidity, winds or pollution on feelings of disease or discomfort. We suppose that the main influencing climatic factor, which could excite multiform biological reactions, is atmospheric electricity, E, whose parameters depend strongly on the content of the air column and on the meteorological conditions in this volume, especially along its ground path. A clear connection between wind speed Vw and coarse aerosol concentration N(T) with electric field intensity E exists only for limited intervals of Vw, and N(T). In these ranges, the mean correlation coefficients p(E; Vw) and p(E; N(T)) are usually up to 0.45. In quiet weather, rho is significantly larger than in the equinox seasons or in transferred weather situations. Strong winds or a considerably increased pollution level lead to fast and deep fading of E and even to principal changes in the form of its diurnal distribution from what is usual for stable atmosphere conditions, while weak air streams or a clear atmosphere have almost no influence on electric state variations.