Effect of pH on the physico-mechanical properties of marble

The physico-mechanical properties of rocks are important parameters in the planning and design of mining and civil constructional works. These properties are adversely affected by acidic and alkaline environments. In the present study, marble rock specimens were tested in the laboratory after treatment with different pH solutions for 15 h. The physico-mechanical properties of the marble were determined in both acidic and alkaline conditions. The study revealed that the strength properties are higher at pH 7 and lower in acidic and alkaline conditions. The strength reduction in acidic conditions is greater than that in the alkaline conditions.      

The effect of crude oil pollution and subsequent fire on the engineering properties of soils in the Niger Delta

The Niger Delta is a major area of crude oil exploration, exploitation and processing. This brief paper reports laboratory tests on polluted and unpolluted soils following an oil blow-out and fire outbreak and concludes that the effects were minimal.      

Fracture properties of marble–mortar compounds

Marble panels for outdoor cladding of buildings are generally fastened with mortar and/or anchors. Due to environmental influences (e.g. solar heat, rain and snow), such panels can start to bow and crack, such that eventually they may detach from the wall, possibly causing damage to humans and the environment. Different marble–mortar compounds have been tested for their mechanical and fracture-mechanical characteristics (adhesive strength, notch tensile strength, specific fracture energy, crack growth resistance and characteristic length) by means of the pull-out test and the wedge-splitting method. The propagation of a crack in the marble–mortar compound is characterized on the basis of fracture-mechanics and by use of the load displacement curve. The advantages of using a mortar bed rather than anchors are considered.      

Non-destructive testing of some Higher Himalayan Rocks in the Satluj Valley

Satluj valley, located in the Higher Himalaya, is undergoing rapid development, mainly because of its high hydropower potential. The paper reports a study to determine whether the engineering properties of the granites, gneisses, quartzites and marbles encountered in the higher Himalayan terrain in the Satluj valley can realistically be determined using the Schmidt hammer and ultrasonic velocity. The results indicate a positive correlation for the granites, quartzites and marbles, but not for the folded, anisotropic gneisses.     

大理石表面锈斑的事故树分析

大理石饰面材料在使用过程中,容易受到人为因素和环境的影响,致使大理石丧失了其保护建筑物墙体、美化建筑物等基本功能,也直接影响着大理石的使用寿命。在大理石材料产生的众多病症中,锈斑是最为常见的。通过安全系统工程的事故树分析方法,作者对引起大理石表面锈斑形成的各个因素进行系统分析,建立以大理石表面产生锈斑为顶上事件的事故树。通过对大理石表面产生锈斑事故树的分析,得到了事故树的最小割集、最小径集和结构重要度,为大理石饰面材料表面产生锈斑的预防提供了可信的参考依据,并给出了大理石锈斑的防治措施。     

Influence of weathering on the engineering properties of Harsit granitic rocks (NE Turkey)

Weathering and hydrothermal alteration of the granitic rocks in the Eastern Black Sea Region (NE Turkey) are important phenomena affecting the engineering projects in the region. The study investigated the probable paths of rock-forming mineral transformations due to weathering in the Harsit granitoid rocks, the changes of the major oxides as a consequence of weathering and the effects of weathering on the engineering properties. To identify the changes in the major oxides, the volume concentrations were considered in relation to the dry density. Chemical leaching during weathering was shown to be significant in changing the minerals. It was concluded that the engineering properties of the weathered granitic rocks can be most reliably predicted by P-wave velocity.      

钢管自密实高强混凝土的工程应用研究

在介绍钢管自密实混凝土特点及应用基础上,综述了国内外在钢管自密实混凝土性能方面的数值计算及试验研究进展,并以工程实例对钢管自密实高强混凝土进行了现场模拟试验和分析,采取的高抛自密实混凝土技术方案,较好的满足了设计和施工要求,可为类似采用该技术的工程做参考。     

浅谈停泵水锤的危害及防护

从不同角度将水锤现象进行了分类,重点阐述了停泵水锤的危害,详细介绍了三种停泵水锤的防护措施,并归纳出选择停泵水锤的防护措施时要注意的几点,以确保泵站安全输水。     

Effects of microfissures on the engineering properties of the marble at Wadi Lisb,Saudi Arabia

The marble at Wadi Lisb was investigated in detail in order to assess its engineering properties and to examine the effect of the microfissures on these properties. The marble is white with some dark bands containing the microfissures and parallel to the regional foliation direction. The samples that are cut parallel to these dark bands have better physical and mechanical properties than those cut perpendicular to them. The general effect of the microfissures on Wadi Lisb marble is similar to their effect on Al Madrakah marble indicating a regional phenomenon. During the quarrying operation, it is recommended to take the direction of the microfissures in consideration and to correct for any deviation during the slapping process.     

Some considerations on the warping of marble façades: the example of Alvar Aalto’s Finland Hall in Helsinki

A scanning electron microscope study was performed on samples cored from the white-marble panels of Finland Hall’s façade which revealed considerable warping only a few years after the building’s completion. The analysis shows that granular decohesion is the most important sign of damage at the microstructural level. The presence of calcium sulphate is clearly recognisable on the façade’s surface, though it appears that chemical attack has failed to penetrate inside the material and, presumably, cannot thus be considered the only cause of decay. Following up on the results of other experimental observations that correlate warping with the degradation of bending strength, flexural tests were performed on four different qualities of white-marble, conditioned by thermal cycles in order to reproduce the damage process. The tests evidence that the four material types present very different resistance to thermal aggression: some varieties hold up very poorly, while others instead remain reliable in the long term.     

雷士德工学院消防安全调研报告

先简要介绍雷士德工学院的历史背景,通过对雷士德工学院旧址的消防安全调研,分析建筑设计之初的消防安全和功能转型为海员医院后的消防措施;再介绍建筑在2008年和2014年的两次消防改造,并提出目前建筑存在的消防安全隐患;最后总结,虽然建筑消防设施较为完善,但仍要加强管理,对建筑不安全之处进一步改善。     

Predicting uniaxial compressive strength,modulus of elasticity and index properties of rocks using the Schmidt hammer

The Schmidt hammer test is a non-destructive method which can be used in both laboratory and field to provide a quick and relatively inexpensive measure of rock hardness. The study investigated the relationship between the Schmidt hardness and modulus of elasticity, uniaxial compressive strength and index properties of nine types of rock including travertine, limestone, dolomitic limestone and schist. The empirical equations developed indicated the Schmidt hardness rebound values have a reliable relationship with the uniaxial compressive strength of rock (r = 0.92). Comparing the results with those reported by other researchers, it is concluded that no single relationship can be considered reliable for all rock types. Whilst the equations developed in this study may be useful at a preliminary stage of design, they should be used with caution and only for the specified rock types.      

On the buckling of axially restrained steel columns in fire

This paper describes the behaviour of restrained steel columns in fire. It follows the introduction of extra load into the column through the axial restraint of the surrounding cooler structure and the consequential buckling. Key to this understanding is the post-failure behaviour and re-stabilisation of the column, which is discussed with reference to a finite element model and an analytical model. Through bi-directional control of the temperature, the finite element model allows the snap-back behaviour to be modelled in detail and the effects of varying slenderness and load ratio are investigated. The analytical model employs structural mechanics to describe the behaviour of a heated strut, and is capable of explaining both elastic and fully plastic post-buckling behaviour.Through this detailed explanation of what happens when a heated column buckles, the consequences for steel-framed building design are discussed. In particular, the need to provide robustness is highlighted, in order to ensure that alternative load paths are available once a column has buckled and re-stabilised. Without this robustness, the dynamic shedding of load onto surrounding structures may well spread failure from a fire’s origin and lead to progressive collapse.     

我国古建筑的木结构构造与火灾危险性分析

我国古建筑是世界上最古老的建筑体系之一,在建造技术和装饰艺术以及布置格局等方面具有悠久的历史传统和辉煌的成就,对我国现代建筑的设计、建造和装饰工艺的发展有着重要而深远的影响.我国古建筑因其合理而有序的布局格局和独特的结构及构造方式,能够在历经上千年的地质变化和自然界各种因素的侵袭而得以保存下来.但是,同所有的现代建筑一...     

Experimental study of water hammer-induced forces and deformations in dry pipe fire protection systems

When designing a fire protection system, every effort should be taken to ensure its maximum operational safety. Therefore, correct identification of the dynamic load affecting the system during water hammer occurrence is essential to increase the operational reliability of such fire protection systems on their design stage. A test stand with a simple deluge system was designed for the experiments. The layout consisted of a distribution duct and one straight branch line (including three different diameter values) equipped with three fire nozzles. However, the main objective of this study is not to study the water hammer itself but, rather, to study the forces and displacements induced by the water hammer. The measurement results will be used to calibrate a mathematical model created using MATLAB software. The verified model will in turn enable numerical determination of the dynamic force values for larger systems. Furthermore, these force values will allow for pinpointing the critical sections, for which it is necessary to prevent displacements or transfer the acting forces to the building structure.     

六盘水地区红黏土的物理力学性质及工程特征

简要描述了广泛分布于贵州省六盘水地区红黏土的成因、基本物理力学性质,并结合工程实例评述确定红黏土的地基承载力的几种方法,指出红黏土具有良好的力学性能,是良好的地基土.     

Experimental study of the mechanical properties of light gauge cold-formed steels at elevated temperatures

In recent times, light gauge cold-formed steel sections have been used extensively as primary load-bearing structural members in many applications in the building industry. Fire safety design of structures using such sections has, therefore, become more important. Deterioration of mechanical properties of yield stress and elasticity modulus is considered the most important factor affecting the performance of steel structures in fires. Hence, there is a need to fully understand the mechanical properties of light gauge cold-formed steels at elevated temperatures. A research project based on experimental studies was, therefore, undertaken to investigate the deterioration of mechanical properties of light gauge cold-formed steels. Tensile coupon tests were undertaken to determine the mechanical properties of these steels made of both low- and high-strength steels and thicknesses of 0.60, 0.80 and 0.95 mm at temperatures ranging from 20 to 800 °C. Test results showed that the currently available reduction factors are unsafe to use in the fire safety design of cold-formed steel structures. Therefore, new predictive equations were developed for the mechanical properties of yield strength and elasticity modulus at elevated temperatures. This paper presents the details of the experimental study, and the results including the developed equations. It also includes details of a stress–strain model for light gauge cold-formed steels at elevated temperatures.     

工程建设中监理现状及改善对策建议

本文对工程建设监理行业现状进行了分析,从监理人员素质、企业水平、市场状况及行业环境等方面论述了目前我国监理行业普遍存在的一些问题,并有针对性的提出了相应改善对策,以促进我国今后工程建设监理事业的持续健康发展.     

道路与铁道工程中的地质灾害评价

针对地质灾害的危害性,对深埋长隧道工程开挖的主要地质灾害问题进行了研究,进行了斜坡坡面地质灾害分析及防治措施评价,探讨了广东公路地质灾害的特点,指出在进行地质灾害评价时,应从成因、特点、防治措施及措施效果等多方面考虑。     

Behavior of steel columns in a fire with partial damage to fire protection

An experimental study is performed on two specimens in a furnace to investigate the fire behaviour of steel columns with partial loss of fire protection. The steel columns are connected by flush end-plates at two ends and the axial load is kept constant with a load ratio of 0.55 subjected to an elevation of temperature. The specimens are protected with 20 mm thickness of fire protection. The damaged length of fire protection is 7% of the complete length of the column for specimen S-1 and 14% for S-2 at the two ends of the steel columns. The temperature of atmosphere around the specimens in the furnace is assumed to follow the ISO834 standard temperature and the temperatures and displacements are measured in the experiment. The temperature distribution along the steel column is modelled by finite element analysis and compared with the measured results. A continuum model is presented to predict the ultimate load capacity or critical temperature of the columns with fire protection damage. Analyses are carried out on the specimens and compared with the experiment. Experimental and analytical results showed that the fire resistance of steel columns with partial damage to the fire protection is reduced. The damage length of the fire protection has a great effect on the fire resistance of steel columns. The failure of the specimens mainly resulted from the buckling or yielding at the portion where the fire protection is damaged.