Finite element modeling and analysis of a cardboard shelter

Constructing shelters from corrugated cardboard panels represents an innovative approach in the construction industry. The cardboard shelters can be used for permanent living or as temporary houses in post natural disaster events. Due to their light weight and also due to the ease of packing, cardboard sheets can be easily shipped to remote areas. This study includes a comprehensive stress analysis of a full-scale cardboard shelter subjected to different wind load conditions. The cardboard is modeled using a laminated orthotropic shell element. The material properties incorporated in the model are based on the results of mechanical tests conducted on individual cardboard components. The study describes in detail the numerical model that was developed to simulate the global and local behavior of full-scale cardboard shelters under wind loads. Seven finite element analyses covering various loading and geometry configurations, including the effect of door and window openings, are conducted. Maximum strains found from the analyses are compared to the ultimate strains obtained from the component tests in order to judge on the level of safety provided by the shelters.     

Laboratory evaluation of smoke detectors for use in underground mines

Laboratory experiments were conducted to determine the responses of a prototype smoke detector and a commercially available photoelectric smoke detector to smoke particles generated from various combustion sources. The prototype smoke detector combines optical scattering measurements with ionization chamber measurements in order to reduce/eliminate nuisance alarms due to the presence of airborne dusts or diesel exhaust particles. The commercially available smoke detector is designed for use in harsh environments where airborne dust represents a major problem due to both nuisance alarms and detector contamination. In the experiments, the responses of the two detectors were measured when exposed to smoke particles from the exhaust of a diesel engine and from a variety of fire sources, including wood, coal, styrene butadiene rubber, and No. 2 diesel fuel. For the solid fuels, data were obtained for both smoldering and flaming combustions. This report describes the experiments, their results, and the use of these results as they apply to early-warning fire sensors capable of the rapid and reliable detection of fires in atmospheres that may or may not be contaminated by either airborne dust or the products produced from diesel engines.     

工程机械停用前的封存保养

较系统地介绍了工程机械在长时间停用前,为避免机械性能下降或质量变化而采取的封存保养的措施和方法。     

Analysis of construction parameters for underground structures installed with use of jet geotechnology

A new approach to physical bases for calculation of parameters of the production process used to install underground structures by jet geotechnology is formulated. Flushing equations are presented for plane and three-dimensional structures. Formulas are derived for approximate determination of the flushing of soil aggregate during jet-induced erosion of cohesive soils.     

长沙南站钢结构防火涂料施工技术

结合某工程实例,探讨了防火涂料的选用和防火机理,归纳了钢结构防火涂料施工前的准备工作,重点阐述了其施工工艺和质量保证措施,通过严格进行质量控制,涂层厚度均达到了规范要求。     

上海浦东浦江茗园地下车库防水堵漏施工

上海浦东某高层建筑地下室和地下车库发生渗漏，根据工程特点，对墙体和顶板分别采用电动泵高压灌浆和手压泵传统灌浆，并结合刚性防水涂料和聚合物砂浆面层设防，取得了预期效果。     

Measurement and scaling of air-surface mercury exchange from substrates in the vicinity of two Nevada gold mines

The state of Nevada has extensive mineral resources, and is the largest producer of gold in the USA as well as fourth in world gold production. Mercury (Hg) is often present in the hydrothermal systems that produce gold deposits, and can be found in elevated concentrations in gold ore. As a result, mining of gold ore in Nevada has been shown to release Hg to the atmosphere from point and non-point sources. This project focused on measurement of air-soil Hg exchange associated with undisturbed soils and bedrock outcrops in the vicinity of two large gold mines. Field and laboratory data collected were used to identify the important variables controlling Hg flux from these surfaces, and to estimate a net flux from the areas adjacent to the active mines as well as that occurring from the mined area pre-disturbance. Mean daily flux by substrate type ranged from 9 ng m^− 2 day^− 1 to 140 ng m^− 2 day^− 1. Periods of net deposition of elemental Hg were observed when air masses originating from a mine site moved over sampling locations. Based on these observations and measured soil Hg concentrations we suggest that emissions from point and non-point sources at the mines are a source of Hg to the surrounding substrates with the amount deposited not being of an environmental concern but of interest mainly with respect to the cycling of atmospheric elemental Hg. Observations indicate that while some component of the deposited Hg is sequestered in the soil, this Hg is gradually released back to the atmosphere over time. Estimated pre-disturbance emissions from the current mine footprints based on field data were 0.1 and 1.7 kg yr^− 1, compared to that estimated for the current non-point mining sources of 19 and 109 kg yr^− 1, respectively.     

Volumetric analysis of rock mass instability around haulage drifts in underground mines

Haulage networks are vital to underground mining operations as they constitute the arteries through which blasted ore is transported to surface. In the sublevel stoping method and its variations, haulage drifts are excavated in advance near the ore block that will be mined out. Numerical modeling is a technique that is frequently employed to assess the redistribution of mining-induced stresses, and to compare the impact of different stope sequence scenarios on haulage network stability. In this study, typical geological settings in the Canadian Shield were replicated in a numerical model with a steeply-dipping tabular orebody striking EW. All other formations trended in the same direction except for two dykes on either side of the orebody with a WNW–ESE strike. Rock mass properties and in situ stress measurements from a case study mine were used to calibrate the model. Drifts and crosscuts were excavated in the footwall and two stope sequence scenarios – a diminishing pillar and a center-out one – were implemented in 24 mining stages. A combined volumetric-numerical analysis was conducted for two active levels by comparing the extent of unstable rock mass at each stage using shear, compressive, and tensile instability criteria. Comparisons were made between the orebody and the host rock, between the footwall and hanging wall, and between the two stope sequence scenarios. It was determined that in general, the center-out option provided a larger volume of instability with the shear criterion when compared to the diminishing pillar one (625,477 m³ compared to 586,774 m³ in the orebody; 588 m³ compared to 403 m³ in the host rock). However, the reverse was true for tensile (134,298 m³ compared to 128,834 m³ in the orebody; 91,347 m³ compared to 67,655 m³ in the host rock) instability where the diminishing pillar option had the more voluminous share.     

Deformational behaviour of roadways in soft rocks in underground coal mines and principles for stability control

Following a brief introduction to the nature of a roadway excavated in soft rocks in underground coal mines, six characteristics featuring its deformational behaviour are formulated and illustrated extensively with data collected over decades. The characteristics are: (1) a high rate of rapid deformation in response to ground pressure redistribution; (2) evident rheological deformation; (3) high sensitivity to stress changes; (4) high sensitivity to water invasion; (5) deformation occurring in all directions of the roadway cross section; and (6) a predominant floor heave component in the roof-to-floor convergence. In view of the nature of an underground roadway located in soft strata, principles for controlling the roadway stability both effectively and economically for the whole service life span are specified. A case study is also presented in order to demonstrate the application of the outlined principles for the stability control of roadways excavated in such soft rocks using a multiple support system with joints.     

Numerical modeling of thawing in frozen rocks of underground mines caused by backfilling

The thawing effect due to backfilling in permafrost mining rocks is investigated. The heat transfer equation in rock and backfill is obtained by considering the effect of phase change, heat generation due to cement hydration and temperature dependent material properties. The governing equations are solved using a finite volume numerical method and the phase change phenomenon is modeled based on the manipulation of specific heat, thermal conductivity and density of rock and backfill. The harmonic mean method was employed to handle the change of thermal properties. The effects of different influential parameters such as cement content of backfill, water content of rock and backfill, thermal conductivity of rock and filling material, and the number of adjacent stopes are investigated. Eventually, using the resulting temperature and phase field, a new parameter regarded as the radius of thawing, is introduced.     

复杂地层各种地下障碍物清理施工技术

结合具体工程实例,探讨了如何经济、快速清除复杂地层、各种地下障碍物,分别阐述了清除表层覆盖原厂房基础、人防设施的施工方法及木桩的清除方案,对今后同类地下障碍物清除施工具有一定指导意义。     

地铁车站大面积钢筋混凝土板施工防开裂技术

分析了混凝土开裂的原因及机理,介绍了设计手段和施工技术方面的控制措施,以达到减少或防止裂缝,提高结构的耐久性和外观质量的目的.     

某地下人防工程土方开挖施工技术

结合某具体案例,从地下人防工程的施工准备、工艺流程、主要工序施工方法、混凝土浇筑、监测等方面全面阐述了地下人防工程的施工过程,积累了相关施工经验,以供类似工程参考。     

地铁车站施工中的监控量测

为实施对施工过程的动态控制,现场监控量测是关键的一环,对现场量测的主要内容逐一进行了介绍,并叙述了监控量测工作的要求以及监控量测的实施阶段,通过对监控量测数据的整理和分析,对可能出现的各种情况作出决策,采取有效措施。     

逆向施工方法在地下通道施工中的应用

为了保证新建筑的地下通道与原市政暗渠施工的顺利进行,通过采用逆向施工的方法,对两者的施工顺序进行了合理的安排,并且应用自密实混凝土等新材料,解决了后续工作中的施工难题,顺利完成了位于暗渠下方地下通道的施工.实践证明:此方法保证了施工的安全,工期及工程质量均达到了预期的目标.     

Development and use of underground space for entertainment and cultural activities in the People's Republic of China

Recent socioeconomic changes in China have led to an increased interest in cultural entertainment and recreational activities. As a result, there is a great need for more theatres, cinemas, music and exhibition halls, museums, cultural centers, children's palaces, education centers, gymnasiums and sports centers. Yet at the same time, there is little aboveground space available for developing such facilities. This article discusses the advantages of constructing recreation and entertainment facilities underground; describes a number of existing such facilities; and presents recommendations for their future planning and design.     

矿山法浅埋暗挖施工对地下管线保护技术

结合工程实例，着重阐述了结构在穿越或邻近地下管线时确保管线不渗不裂、保证管线正常使用，地层变形控制在允许范围内的技术要点，以保证地下管线的安全。     

浅谈基坑施工中的地下水处理

介绍了基坑开挖的条件及地下水处理的必要性，阐述了地下水的处理方法，着重对轻型井点，深井井点的降水工艺及施工注意事项做了探讨，有利于基坑开挖，保证工程质量及安全。     

浅析地下防水混凝土结构施工要点

结合多年地下防水混凝土结构的施工实践，介绍了影响防水混凝土结构的因素，系统阐述了保证地下防水混凝土结构质量的要点，并提出施工中容易出现的问题及解决方法。