Characterizing cyclic and static moduli and strength of compacted pavement subgrade soils considering moisture variation

Compacted soils are widely used as the subgrade layer for pavements. Knowledge of the mechanical properties of subgrade soils under cyclic and static loading conditions and their variation under the influence of environmental factors is required for the rational design of pavements based on mechanistic methods. This paper presents an experimental investigation of the cyclic and static moduli and the strength properties of seven different compacted Canadian subgrade soils considering the variation in the post-compaction moisture content. Cyclic triaxial tests were performed to reliably determine the resilient modulus (M_R). Unconfined compression tests, which allow an unloading-reloading loop at 1% strain, were performed to determine the deviator stress (S_u1%) at 1% strain, the reloading elastic modulus (E_1%) at 1% strain and the unconfined compressive strength (q_u) at failure. The physical properties, the chemical and mineralogical compositions, and the soil-water characteristics of these soils were also determined. Relationships were developed to predict the M_R from the S_u1%, E_1%, q_u and soil physical properties for the investigated subgrade soils because the experimental determination of M_R is both expensive and time-consuming. The studies presented in this paper provide useful information and approaches that can be used to promote the implementation of mechanistic pavement design methods using simple techniques.     

Laboratory tests to evaluate effectiveness of wicking geotextile in soil moisture reduction

A new type of woven geotextile, referred to as wicking geotextile, was developed and introduced to the market. Since this wicking geotextile consists of wicking fibers, they can wick water out from unsaturated soils in a pavement structure thus resulting in an increase of soil resilient modulus and enhance performance of roadways. In this study, a physical model test was developed to evaluate the effectiveness of the wicking geotextile in soil moisture reduction for roadway applications. A test box with a dimension of 1041 mm in length, 686 mm in width, and 584 mm in height was used in this study. Two HDPE plastic panels were used to separate the box into two sections, one containing a dehumidifier and the other backfilled with soil. The dehumidifier was adopted to collect the water, which was wicked out from the soil by the wicking geotextile and evaporated into air. Test results show that (1) the wicking geotextile wicked water out from the soil even at the moisture content close to the optimum moisture content and (2) the comparison of soil moisture contents before and after rainfall demonstrated that the wicking geotextile maintained the soil moisture contents after rainfall close to those before rainfall and had an effective distance for the soil moisture reduction.     

Coupled simulation of heat and moisture transport in air and porous materials for the assessment of moisture related damage

This paper describes the coupling of a model for heat and moisture transport in porous materials to a commercial Computational Fluid Dynamics (CFD) package. The combination of CFD and the material model makes it possible to assess the risk of moisture related damage in valuable objects for cases with large temperature or humidity gradients in the air. To couple both models the choice was made to integrate the porous material model into the CFD package. This requires the heat and moisture transport equations in the air and the porous material to be written down in function of the same transported variables. Validation with benchmark experiments proved the good functionality of the coupled model. A simulation study of a microclimate vitrine for paintings shows that phenomena observed in these vitrines are well predicted by the model and that data generated by the model provides additional insights in the physical mechanisms behind these phenomena.     

The behaviour of masonry walls subjected to fire: Modelling and parametrical studies in the case of hollow burnt-clay bricks

A thermo-mechanical model is adopted in order to investigate the fire behaviour of clay masonry walls. In this analysis, conductive, convective and radiative thermal transfers are considered together with local energy consumption due to phase changes. These latter are essentially initiated by both the vaporisation of adsorbed water and the chemical transformation of clay under rising temperatures. Therefore, experimental tests at both the material scale and the brick scale are performed in order to identify the parameters that characterise the thermo-hygral behaviour of clay. For this purpose, numerical simulations are carried out on the experimentally tested hollow bricks in order to determine by back analysis these material parameters. The thermal model being validated, the thermo-mechanical behaviour of a masonry wall subjected to fire, is thereafter investigated by adopting a full three-dimensional finite-element analysis. Numerical simulations results are compared to the experimentally measured ones in terms of both temperature and out-of plane displacement fields. In this analysis, it is shown that a non-linear elastic behaviour for bricks and mortar with temperature-dependent mechanical parameters is sufficient to retrieve the overall behaviour of thin masonry walls. Finally, a parametric study provides the influence of each material parameter on the fire behaviour of the partition walls.     

Effect of moisture and temperature variation on DOC release from a peatland: conflicting results from laboratory, field and historical data analysis

Peatlands are large repositories of atmospheric carbon and concern has been raised over the stability of this carbon store because increasing dissolved organic carbon (DOC) concentrations have been observed in peatland drainage waters. A number of potential causes have been proposed in the literature, and conflicting results among studies conducted at different spatial and temporal scales suggest that the methodological approach may be an important confounding factor. The objective of this study was to determine the influence of moisture and temperature on DOC release from a south-central Ontario peatland during the fall (a major export period) following three commonly used approaches: laboratory microcosms, an intensive field study and analysis of long-term data (1980-2008). The effect of variations in temperature and moisture differed among microcosm, field study and analysis of the long-term record. Water content was important at the microcosm scale as DOC concentration and aromaticity increased with peat water-saturation. Drought caused a decrease in DOC concentration and pH, and an increase in sulphate and base cation concentrations. In contrast, the field study indicated that DOC concentration was strongly associated with temperature, and weakly correlated (negatively) with stream discharge. Average fall DOC concentration (but not export) increased over the 29 year record, and was correlated with fall discharge and precipitation (negative) and summer precipitation and fall stream pH (positive). As no common strong predictor of fall DOC was found at three scales of investigation at a single, well-studied site, it may be unreasonable to expect to identify a universal driver behind the widespread increase in DOC concentration.     

高液限土在填方中的利用与含水量控制

分析了高液限土的物理特性,介绍了现阶段常见的处治方案,结合工程实际情况阐述了处治的方法和措施以及施工过程中的含水量控制,从而降低工程成本,保证了工程质量。     

政府主导走向多方参与:日韩国土规划的新动向

日本和韩国一直非常重视国土规划,在过去的半个世纪中,两国的国土开发也取得了显著的成效。在当今全球化和东亚经济急速发展的背景下,两国都适时调整本国的国土规划以适应新的社会经济形势。本文首先总结了两国历次国土规划的特点和经验,并结合他们国土规划的新动向,得出对我国的启示:国土规划应重视国际化,充分发挥城市群对促进区域协调发展的作用,中央适当向地方分权以提高效率,以及提高应对自然灾害的能力。     

含水率对蒸压加气混凝土砌块抗压强度的影响

指出含水率对蒸压加气混凝土材料性能的影响较大,通过对灰砂蒸压加气混凝土材料在不同含水状态下的立方体抗压强度的试验研究,分析了不同含水率对砌块抗压强度的影响,并对此材料的使用提出了建议。     

我国不同气候区典型外墙的热湿迁移特性及霉菌生长风险评估

针对国家建筑标准设计图集09J908-3中常见建筑外墙的热湿迁移特性及霉菌生长风险展开研究,以5个代表城市(沈阳、北京、上海、福州和昆明)为例,采用WUFI Pro 6.2软件模拟了外墙的非稳态热湿传递过程.结果表明:墙体内部的热湿动态迁移过程受主体材料、保温材料和当地气象条件等多个因素的共同影响;加气混凝土(AAC)...     

冻融与荷载作用下土体内部孔隙水压力、水分变化规律及其模型试验研究

 在季节冻土区,反复冻融作用导致土体孔隙水压力发生变化,进而导致土体中水分的迁移;对土体施加静荷载,土体内部应力场发生变化,土体内的水分和孔隙水压力亦发生变化。通过模型试验,研究无荷载和荷载两种条件下土体内部孔隙水压力和水分场随冻融循环作用的变化规律,试验结果表明：在荷载和无荷载两种条件下,孔隙水压力在初期呈负值稳定变化,然后快速增大,最后呈周期性变化。在无荷载条件下,随着土体深度的增加,孔隙水压力增大,水分含量减小;在荷载条件下,土体上部和中部位置处的孔隙水压力和水分含量都大于荷载两侧。在一个冻融周期内,土体内部孔隙水压力和水分含量都随温度的升高而增大,随温度的降低而减小,而且孔隙水压力和水分含量随温度的变化都具有滞后性。     

School attendance and daily respiratory symptoms in children: influence of moisture damage

We investigated the effect of weekends and school holidays on the daily frequency and severity of respiratory and other symptoms among children attending schools with (index) or without (reference) moisture damage in Spain, the Netherlands, and Finland. Throughout 1 year, parents of 419 children with a respiratory condition attending index (n=15) or reference (n=10) primary schools completed three symptom diaries. We assessed associations between lower respiratory tract, upper respiratory tract or allergy, and other symptom scores and school day, weekend, or summer holiday using mixed regression models stratified by country and moisture damage. We evaluated interactions between moisture damage and type of day. We combined country‐specific estimates (incidence rate ratios [IRRs] and 95% confidence interval [CI]) in meta‐analyses. Symptom scores were lower during weekends and holiday. Lower respiratory tract symptoms were statistically significantly less common during holiday with strongest effect in index schools (IRR=0.7; CI=0.6–0.8). Reporting of other symptoms was more reduced during holiday in index (IRR=0.6; CI=0.4–0.9) than in reference (IRR=0.95; CI=0.8–1.2) schools (interaction P<.01). In conclusion, symptoms were less frequent and/or severe during summer holiday and weekends. This pattern was stronger among children attending moisture‐damaged schools, suggesting potential improvement in moisture damage‐related symptoms during school breaks.     

Sources of dissolved mine drainage and atmospheric transported lead: A comparative case study in Japan and Sweden

A comparative case study in Naganobori Japan and Falun Sweden of runoff water from copper mines shows that the water and its particulates, filtered with a cutoff of 0.45 μm, have different lead isotope ratios pointing to different origins for the lead. While the larger particles have a lead ratio indicative of the atmospheric anthropogenic pollution the soluble lead has that of the copper ores. The domestic atmospheric lead ratio in Japan is homogeneous and characteristic of emissions from the incineration of waste. Lead pollution transported from the Asian continent by westerly winds can be distinguished from the Japanese pollution by its more thorogenic lead ratios, in for example analyses of copper moss from Naganobori.     

中日在小户型空间尺度和面积分配上的差异

通过比较中日在户型空间尺度和面积分配上的差异,揭示日本小户型住宅对我们的两点启发:一是推广90m~2住宅,首先需要空间尺度上的观念转变,确立更精细地使用空间的态度和措施;二是缩小户型面积,不应该牺牲或降低居室以外配套部分的功能。     

Temporal variation of Pu/Pu atom ratio and Pu inventory in water columns of the Japan Sea

The ^239+240Pu concentrations and ²⁴⁰Pu/²³⁹Pu atom ratios were determined by alpha spectrometry and double-focusing SF-ICP-MS for seawater samples obtained in 1984 and 1993 from the Yamato and Tsushima Basins of the Japan Sea in the western North Pacific margin. The total ^239+240Pu inventories in the whole water columns were approximately doubled during the period from 1984 to 1993 in the two basins. The increasing rates were estimated to be 5.1 Bq m⁻² yr⁻¹ in the Yamato Basin and 4.2 Bq m⁻² yr⁻¹ in the Tsushima Basin and they corresponded to ~ 0.02% of the annual ^239+240Pu inflow rate into the Japan Sea through the Tsushima Strait. The mean ²⁴⁰Pu/²³⁹Pu atom ratios were ~ 0.240 and significantly higher than the mean global fallout ratio of 0.18. Furthermore, there were no temporal or spatial variations of ²⁴⁰Pu/²³⁹Pu atom ratios during this period in the Japan Sea. The total ^239+240Pu inventories originating from the close-in fallout increased from 17.6 Bq m⁻² to 34.6 Bq m⁻² in the Yamato Basin and from 20.1 Bq m⁻² to 34.6 Bq m⁻² in the Tsushima Basin; however, the relative percentage of ~ 40% from the close-in fallout was unchanged during this period. A likely mechanism for the increasing Pu inventory would be the continuous inflow of the Tsushima Current from the western North Pacific, and the removal of Pu from surface waters by scavenging onto the settling particles, followed by regeneration of Pu from the settling particles during the downward transport.     

Acquisition of ground penetrating radar data to detect lava tubes: preliminary results on the Komoriana cave at Fuji volcano in Japan

Ground penetrating radar (GPR) has been successfully used to detect a lava tube in a basaltic lava flow from the Fuji volcano, Japan. The target lava tube, Komoriana cave, is in the northern part of the Aokigahara lava flow which was emplaced over 1,000 years ago. The lava tube was detected by simply dragging the GPR antenna along a prefecture road, demonstrating the advantages of this method compared with detailed mapping and geological investigations. As a massive basaltic lava flow allows deep penetration of the radar pulse, the reflection radar profile obtained showed two very clear structures which were interpreted from the waveforms to be the roof and the bottom of the lava tube from the waveforms alone. This was subsequently confirmed by careful survey measurements of the Komoriana cave lava tube. The feasibility study clearly demonstrated that GPR is a very effective and convenient tool for discovering unknown lava tubes hidden deeply inside lava flows.     

Inflammatory potential in relation to the microbial content of settled dust samples collected from moisture‐damaged and reference schools: results of HITEA study

Aiming to identify factors causing the adverse health effects associated with moisture‐damaged indoor environments, we analyzed immunotoxicological potential of settled dust from moisture‐damaged and reference schools in relation to their microbiological composition. Mouse RAW264.7 macrophages were exposed to settled dust samples (n = 25) collected from moisture‐damaged and reference schools in Spain, the Netherlands, and Finland. After exposure, we analyzed production of inflammatory markers [nitric oxide (NO), tumor necrosis factor‐α (TNF‐)α, interleukin (IL)‐6, and macrophage inflammatory protein (MIP)2] as well as mitochondrial activity, viability, apoptosis, and cell cycle arrest. Furthermore, particle counts, concentration of selected microbial groups as well as chemical markers such as ergosterol, 3‐hydroxy fatty acids, muramic acid, endotoxins, and glucans were measured as markers of exposure. Dust from moisture‐damaged schools in Spain and the Netherlands induced stronger immunotoxicological responses compared to samples from reference schools; the responses to Finnish samples were generally lower with no difference between the schools. In multivariate analysis, IL‐6 and apoptosis responses were most strongly associated with moisture status of the school. The measured responses correlated with several microbial markers and numbers of particles, but the most important predictor of the immunotoxicological potential of settled dust was muramic acid concentration, a marker of Gram‐positive bacteria.     

Devolution, new regionalism and economic revitalization in Japan: Emerging urban political economy and politics of scale in Osaka-Kansai

Determining that the centralized political system is the cause of its persistent economic problems, Japan’s political leaders have been promoting neoliberalism-oriented state decentralization since the early 2000s. Stimulated by this policy, the prefecture of Osaka - the center of Japan’s second economic region - and its neighbors established a federation-type regional government in December 2010. However, some members left this regionalist coalition before its launch, which demonstrates the existance of internal tensions. In this study, the frameworks of Institutional Collective Action and politics of scale are applied to examine the regionalism decision-making process. Our findings suggest: (1) systemic political and economic biases run within the regionalism and (2) the likely urban economic and governance conditions after the devolution would be much more uncertain and messier than the reform advocates suggest they would be.     

遗产廊道的深刻鉴别与再发现——日本线性历史景观研究中的历史地理学先发探查与解析

景观考古学的前期探查需求，及其与风景园林、古建筑学等相关学科的学际综合研究的发展，对中国历史地理学的研究提出新的要求。现代日本史地学者对于古驿道系统、历史性街道系统等遗产廊道的深刻鉴别及创造性的再发现表明：基于历史背景考察、文献记录核检、大比例尺地图与现场实勘比定等复合分析的历史地理学先发探查与解析方法，对于此类线性景观的历史演变与复原研究来说是一种既具研究效率、又不可或缺的分析手段，对中国开展景观考古研究与大遗址保护也深具启发意义。     

国家仪式的舞台与想象的共同体——近代日本公共空间之创造

公共空间在建立国民国家的过程中扮演了国家仪式的舞台的角色。作为新首都的中心,东京皇居前广场在明治维新之后举行了很多国家仪式。通过研究分析最初的国家仪式天皇巡幸,皇居前广场的宪法颁布式,以及和皇居前广场相关的国民教育型公共空间上野公园和军事性公共空间青山练兵场,探究日本近代与前近代完全不同的、具备国民国家形成初期的公共空间特征同时详细阐述日本举行首都国家仪式的公共空间在共同体意识培养过程中的作用。     

Impact of wind-driven rain on historic brick wall buildings in a moderately cold and humid climate: Numerical analyses of mould growth risk, indoor climate and energy consumption

This paper gives an onset to whole building hygrothermal modelling in which the interaction between interior and exterior climates via building enclosures is simulated under a moderately cold and humid climate. The focus is particularly on the impact of wind-driven rain (WDR) on the hygrothermal response, mould growth at interior wall surfaces, indoor climate and energy consumption. First the WDR load on the facades of a 4 m × 4 m × 10 m tower is determined. Then the hygrothermal behaviour of the brick walls is analysed on a horizontal slice through the tower. The simulations demonstrate that the impact of WDR loads on the moisture contents in the walls is much larger near the edges of the walls than at the centre. The obtained relative humidity and temperature at the interior wall surfaces are combined with isopleths of generalised spore germination time of fungus mould. The results show that WDR loads can have a significant impact on mould growth especially at the edges of the walls. Finally, for the case analysed, the WDR load causes a significant increase of indoor relative humidity and energy consumption for heating.