瑞利波法估算地基抗剪强度的应用

发展原位、快速、经济、无损地测试地基抗剪强度的方法具有重要的实际意义。利用粘性土非线性弹性模型、摩尔-库仑强度理论以及土的波动理论,建立剪切波速度与土体抗剪强度的关系式。通过实际工程的瑞利波法测试,证明有一定的适用性。     

干粉灭火系统计算研究

进行干粉灭火系统计算研究的主要目的是为干粉灭火系统的设计或设计规范的编写提供依据 ,以保证设计具有科学性、可靠性和可行性。基于这一宗旨 ,干粉灭火系统计算研究的内容主要包括确定系统中各个管段的管径、系统的工作压力和泄压口面积等。1　管道直径的确定管道直径的大小由管道中通过的气固两相流体的体积和适宜的流动速度决定 ,前者可依据管道中需要输送的干粉量、驱动气体的种类、驱动气体系数、环境温度和管道中的压力计算出来 ;而后者则需要通过试验确定。为使干粉灭火系统管道内干粉与驱动气体不分离 ,干粉 -驱动气体二相流必须…     

Spatial and temporal trends of petroleum hydrocarbons in wild mussels from the Galician coast (NW Spain) affected by the Prestige oil spill

Polycyclic aromatic hydrocarbons (PAHs) were determined in tissues of wild mussels (Mytilus galloprovincialis) from the Galicia coast (NW Spain) in order to assess the extent of the environmental impact caused by the Prestige oil spill (November 13, 2002). Three sampling campaigns were carried out in February, June and November 2003 at 24 stations along the Galicia coast, from La Guardia (Pontevedra) to Ribadeo (Lugo). The spatial distribution of PAHs found in the first sampling period, clearly revealed the central area (Costa da Morte) as the most affected by the oil spill. In these stations, concentrations up to 7780 microg/kg dw of the sum of 13 parent PAHs were found 2-3 months after the spill. Molecular parameters within the aliphatic and aromatic fractions confirmed the presence of the Prestige oil in these samples. The levels markedly decreased at most of the stations in the second sampling and recovered to levels found before the spill in November 2003, 1 year after the accident (29-279 microg/kg dw, av. 133+/-83 microg/kg dw). However, a certain increase was observed in some sites which could be related to the remobilization of oil residues from still unclean intertidal spots or sediments due to the winter marine weather conditions.     

Betons a hautes performances,a granulats artificiels actifs

High strength concretes, in particular at early ages (more than 40 MPa at 3 days and up to 80 MPa at 7 days), are obtained by replacement of certain granular size ranges of sand or gravel by cement-active artificial aggregates in a given concrete composition elaborated with a local supply of aggregates and cement. The strengthening of the paste-aggregate bond by chemical reactions between the artificial aggregates and the cement also involves an improvement of other concrete performances and not only of mechanical strengths. The cracking ability is decreased, the wear strength is higher, and water permeability is low or even nil for certain compositions. The laboratory results are confirmed by tests on the site and show the possibility of achieving high strength concretes without any particular selection of cement and natural aggregates.     

Concurrent denitrification and oxygen uptake in microbial films

Mixed microbial films were grown on the inner walls of a tubular reactor with recirculation of the reactor contents and continuous flow-through of nutrient solution. The loss of total oxidized nitrogen was correlated to the film population, the nitrite concentration and the dissolved oxygen concentration in the reactor. When film population was greater than 0.5 × 10⁹ cells cm⁻², reactor dissolved oxygen concentration greater than 1 mg l⁻¹ had little effect on the nitrate loss. Nitrate loss declined for film populations greater than 2 × 10⁹ cells cm⁻². Models based on Monod and zero-order microbial kinetics were calibrated using these data and a nonlinear least squares method. There was little difference in the residual errors with these methods.     

现代控制技术在工程机械上应用的探讨

以摊铺机控制系统为例，阐述了CAN总线在工程机械现代控制系统中的应用，并对工程机械远程监控系统作了初步探讨。     

Tunnelling projects in Southern Africa

Until some thirty years ago tunnelling in southern Africa for civil engineering purposes had been on a relatively small scale and of a sporadic nature. The first major tunnel to be built in the region was the 82 km long Orange-Fish Tunnel. Since 1970 more than 175 tunnels with an aggregate length of just over 400 km have been built. Much of the first phase of the Lesotho Highlands Water Project, which will have more than 100 km of tunnels, is about to be completed. The last thirty years represent the busiest period of tunnelling by civil engineers that southern Africa has ever known. The paper starts by summarising the early history of tunnelling in the region, and goes onto describe recent and current tunnelling projects. It also gives an indication of the possible demand for tunnels in the future.     

Photodecomposition du bioxyde de chlore et des ions chlorite par irradiation u.v. en milieu aqueux-partie II. Etude cinetique

The decomposition of ClO₂ and ClO₂⁻ by u.v. radiation leads to the production of chlorate, chloride and oxygen as end-products via complex reactions which are initiated by the products generated by the primary reactions of photolysis (Buxton and Subhani, 1972a; Mialocq et al., 1973; Karpel Vel Leitner et al., 1992). As far as the rate of decomposition is concerned, Bowen and Cheung (1932) and Zika et al. (1985) have shown that the quantum yield of photodecomposition of chlorine dioxide (overall reaction) increases when the wavelength decreases [Zika et al. (1985): φ = 0.46 at 366 nm and 1.4 at 296.7 nm]. However, the values of the quantum yield of photodecomposition of ClO₂ and ClO₂⁻ at 253.7 nm as well as the quantum yields for the primary reactions of photolysis of ClO₂ and ClO₂⁻ at different wavelengths are not given in the literature.The aim of this work was to study the kinetics of photodecomposition of chlorine dioxide and of chlorite by u.v. irradiation.     

Radon concentration in houses over a closed Hungarian uranium mine

High radon concentration (average 410 kBq m-3) has been measured in a tunnel of a uranium mine, located 15-55 m below the village of Kovágószolos, Hungary. The mine was closed in 1997; the artificial ventilation of the tunnel was then terminated and recultivation works begun. In this paper, a study has been made as to whether the tunnel has an influence on the radon concentration of surface dwellings over the mining tunnel. At different distances from the surface projection of the mining tunnel, radon concentration, the gamma dose, radon exhalation and radon concentration of soil gas were measured. The average radon concentration in the dwellings was 483 Bq m-3. Significantly higher radon concentrations (average 667 Bq m-3) were measured in houses within +/-150 m from the surface projection of the mining tunnel +50 m, compared with the houses further than the 300-m belt (average 291 Bq m-3). The average radon concentration of the soil gas was 88.8 kBq m-3, the average radon exhalation was 71.4 Bq m-2 s-1 and higher values were measured over the passage as well. Frequent fissures crossing the passage and running up to the surface and the high radon concentration generated in the passage (average 410 kBq m-3) may influence the radon concentration of the houses over the mining tunnel.     

长江干堤加固工程北闸段沥青混凝土路面施工

结合工程概况,介绍了沥青混凝土面层的施工工艺,分别从基层表面处理、透油层施工、施工放样等方面进行了阐述,并对施工技术问题及处理措施进行了论述,从而为沥青路面的施工积累了有益的经验。