高地温隧道斜井施工正洞及迂回导坑通风降温系统研究及优化

根据西双版纳隧道2#斜井辅助坑道较长特点、西双版纳隧道属高地温隧道以及新增迂回导坑整体通风困难的情况,提出在原有通风条件下增设储风室,利用风机和通风管将新鲜空气送入储风室,储风室进口安装制冷机,风室内储存风经过制冷后再送入各掌子面,形成斜井、正洞、迂回导坑一体接力压入式通风方式。通过两种通风方式分量、所需风机等比选出该隧道最佳通风系统,最终实现通风系统的最优化。     

软电缆的护套新材料SRT热塑性弹性体

软电缆的护套新材料ＳＲＴ热塑性弹性体上海橡胶制品研究所研制的ＳＲＴ热塑性弹性体软电缆护套料，除了具有良好的耐油、耐屈挠、耐天候和不延燃性能外，还具有优异的加工成型性能。ＳＲＴ热塑性弹性体及其所制成的电缆和可重接插头经检测全部合格，经国家电线电缆质量监...     

电缆防火涂料在高速公路隧道中的应用研究对比

在运营中的高速公路隧道,由于防火需要,现在基本都在使用膨胀型电缆防火涂料。本课题通过试验应用对比,确认电缆防火改性涂料(纳米技术)与普通水性电缆防火涂料在高速公路隧道这一特殊环境下的使用效果。为高速公路隧道电缆防火和消防设计提供参考依据。     

宝坪高速天台山隧道2号通风竖井施工技术

随着公路隧道的迅猛发展,通风竖井作为长大公路隧道的重要组成部分,竖井施工技术亦日益重要,成井的速度在很大程度上由施工技术和机械设备来决定,但也与先进的管理方法和高素质的施工人员密切相关。以天台山隧道2号通风竖井施工为例,探讨通风竖井施工技术与管理,为今后类似工程提供参考依据。     

装配式电缆隧道施工技术及其质量控制

针对装配式电缆隧道中的防水构造、沉降控制等施工难点问题展开研究。基于装配化设计结果提出了纵向连接和顶板-侧壁连接等关键位置的合理防水构造及其施工方法。并根据现行相关规范提出了装配式电缆隧道标准段的生产制作、养护、运输、吊装以及拼接等施工关键工艺的质量控制措施，结合有限元分析结果制定了装配式电缆隧道沉降监测方案。     

带束层脱层对轮胎均匀性的影响

发生在钢丝带束层之间的脱层对轮胎在低速和高速运行时测得的所有均匀性参数有影响。在研究的两种速度条件下，径向力和横向力与脱层宽度无关，均随着脱层长度的增大而增大。高速运行条件下测得的纵向力表明，纵向力随着脱层长度的增大而增大，脱层的宽度对纵向力也略有影响。     

多匝道特长公路隧道不同通风方式下通风效果的数值模拟研究

本研究通过使用fluent软件对某在建多匝道特长公路隧道的不同通风方式进行模拟,综合考虑温度、风速、风量多个因素下不同通风方式对此隧道通风特性的影响。在模拟中主要选取全射流通风方式、通风井排出、及通风井排出式+射流风机进行对比。研究结果表明通风量、风速相同的情况下,通风井排出式通风在隧道高平面3米高、6米高处对co扩散影响明显效果明显但隧道尾部排污效果不佳;纵向射流通风与通风井排出式+射流风机通风对低和高平面的co扩散影响明显,但纵向射流通风方式会致使co聚集在隧道中段难以排出,整体通风排污效果次于通风井排出式+射流风机通风。     

光伏用PET薄膜力学性能测试结果的影响因素

本论文主要讨论了影响光伏用PET薄膜断裂拉伸强度与断裂伸长率测试结果的因素。分别从制样宽度、夹持长度与拉伸速度三个方面进行分析,其中制样宽度对拉伸强度与断裂伸长率均没有明显影响;夹持长度与断裂伸长率有较明显影响,夹持长度越大测试断裂伸长率越小;拉伸速度对拉伸强度和伸长率均有一定影响,拉伸强度与断裂伸长率均随着拉伸速度的增大而减小。     

一起油罐通风电缆起火燃烧事故的分析

某油库进行油罐清洗通风时,发生了通风电缆起火燃烧危险情况。由于油库及时进行了处理和解决,从而避免了一起因通风电缆起火燃烧可能引发的油罐爆炸燃烧重大事故的发生。     

隧道与地下工程施工通风特性及关键技术研究

从工程施工进度的方面进行分析,长大隧道和复杂地下洞室群作业过程中的通风状况是其关键的影响因素,特别是在高温高湿、高海拔的区域、瓦斯隧道、陡坡斜井多工作面等施工环境下,这种影响显得更加突出。鉴于此,改进施工通风工艺具备极其重要的实践价值及意义,一定要运用现代化的理论及技术,有效计算并且分析通风过程,进而科学地设计通风。鉴于此,文章对长大隧道与复杂地下工程施工通风特性及关键技术进行深入的研究,以期实现通风的科学化和合理化。     

Burning behavior of cable tray located on a wall with different cable arrangements

Cable fire risk analysis is important for fire protection design in nuclear power plants, where multiple horizontal cable trays are mostly located on the walls. Fire experiments using three cable trays with different cable arrangements were conducted in a confined room to investigate the burning behavior of a cable tray on a wall. A corner was formed by the side wall and the cable tray. Hot smoke emitted from the burning cable was trapped in the corner and then ignited the cable on the bottom surface of the upper cable tray. It is found that for cables densely packed together, spread of flame on the bottom surface of cable tray was clearly observed and increased the mass loss of cable burning during the growth stage of a cable tray fire. For cables arranged further apart, vertical propagation from the bottom tray to the top tray was fast and dominated the mass loss of cable burning.     

Comparison of large-and small-scale heat release tests with electrical cables

A total of 21 electrical cables were made, all with identical construction but differing in the chemical composition of their plastic components, both jacket (or sheath) and insulation. All the compounds used were commercially available materials, but they covered a variety of polymers, both halogenated and non-halogenated. All cables were tested in a large-scale cable tray test, the proposed ASTM D9.21 test, based on the IEEE 1202 or the CSA FT-4 test, modified to measure heat and smoke release in the duct and with a total length of 2.44 m. The peak rate of heat release measured served as an excellent criterion for distinguishing between cables passing and failing the test (the traditional criterion being char length). The average rate of heat released also served to distinguish the two classes of cables. Moreover, cables passing the test tended to release less smoke than those failing the test. The cables were also tested in the IEC 332-3 cable tray test. The small-scale fire test used for the cables was the cone calorimeter, ASTM E 1354. The trends observed in this heat release test were similar to those in the large-scale test. The results indicate that cables with excellent fire performance can be made by using a variety of materials, so that it would seem to follow that it is important to specify fire performance and leave material choice to manufacturers.     

Mathematical modelling of fire development in cable installations

In 1996 DG XII of the European Commission (Research and Development) approved a 3 year project on the fire performance of electrical cables. Within this FIPEC project, a major part of the work involved correlation and mathematical modelling of flame spread and heat release rate in cable installations. The FIPEC project has developed different levels of testing ranging from a small‐scale, cone calorimeter test procedures developed for cables and materials, a full‐scale‐test procedure based on the IEC 60332‐3, but utilizing HRR and SPR measurements, and a real scale test conducted on model cable installations. Links through statistical correlations and mathematical fire modelling between these levels were investigated and the findings are presented in this paper. These links could form the scientific foundations for standards upon which fire performance measurements can be based and for new fire engineering techniques within fire performance based codes. Between each testing level correlation, numerical and mathematical models were performed. All of the models were based on the cone calorimeter test method. The complexity of the models varied from correlation models to advanced physical pyrolysis models which can be used in CFD codes. The results will allow advanced prediction of cable fires in the future. Also a bench mark was established for the prediction of cable performance by means of data obtained from the constituent materials. Copyright © 2002 John Wiley & Sons, Ltd.     

New ATH developments drive flame retardant cable compounding

Over the past 15 years, halogen free, fire retardant cable systems have gained a large market volume. Systems fulfilling the European norm IEC 60332-3 have become an acceptable part of cable makers technology. Developments in the raw materials field, in compound formulation and polymer processing techniques have led to significant reductions in the production costs of compounds and cables. The development of raw materials, leading to improved compound properties is an ongoing process. Cost reductions of existing compound formulations and cable systems as well as the development of new cable systems showing the highest levels of fire security is the driving force. Dr. Reiner Sauerwein of Nabaltec GmbH describes recent developments in the area of fine precipitated aluminium hydroxide/alumina trihydrate — the most important flame retardant filler used to produce fire retardant cable systems.     

Experimental and numerical analysis of the influence of cable tray arrangements on the resulting mass loss rate and fire spreading

In the context of industrial buildings and power plants, electrical installations and cable trays represent a main fuel load and a potential initial fire source due to possible short circuits or comparable malfunction. Furthermore, a fire can spread from one tray to additional trays mounted above and/or horizontally on one tray. Because of the high significance of cable fires, several research projects have been carried out, investigating the fire behaviour of cables from small‐scale tests, eg, the cone calorimeter, up to large‐scale tests, analysing complete cable tray constructions. The goal of the work presented in this paper is the extension of the knowledge regarding the influence of geometrical parameters like the packing density and tray distance on the burning behaviour and fire spread of cable tray installations. The results are considered, together with test results from the literature, to quantify the main physical parameters describing the burning behaviour. In a next step, the general applicability of these parameters as input data for the parametrization of the source term of numerical simulations is shown. The test results show that the burning behaviour and the fire spreading highly depend on the cable arrangement of the cables on the cable tray, in combination with other boundary conditions. By applying the results as input for a fire simulation, the mass loss rate is considered appropriately.     

无卤低烟阻燃耐火电缆及其工艺的探讨

近年来,国家对于电缆行业的监督管理越来越严格,客户对于电缆的各种常规指标也有了一定的了解.然而对于电缆的部分性能,客户却难以进行测量或者是判断其是否能够达标.其中低烟指标以及阻燃性等都是难以进行判断的指标.同时,各种新技术的出现对于电缆的低烟阻燃、耐火性等也有着较大的影响.文中,主要介绍无卤低烟阻燃、耐火电缆产品的性能...     

Development of a flame-resistant noncontaminating PVC jacket for coaxial cable

The migration of plasticizer from a PVC jacket into the polyethylene core of a coaxial cable can significantly alter the high-frequency transmission characteristics of the cable by effectively increasing the dissipation factor of the polyethylene. In order to determine the effect of plasticizer type on transmission loss, a series of PVC-jacketed polyethylene core coaxial cables was manufactured, each jacket with a different plasticizer. Transmission loss was found to be directly related to plasticizer volatility. A linear trimellitate plasticizer gave stable electrical performance with a good balance of properties, including processing, cost, and fire resistance.     

Research on the plume shape under optimal wind environment to prevent the smoke backflow and combustion gains in utility tunnel

The utility tunnels have been applied extensively to run the various pipelines in the urban areas such as the gas pipeline, electrical power cables, and the likes. Contradicting with the rapid development of the utility tunnels is the ambiguity of the fire protection code to which one critical point is whether to ventilate in the fire accident, which is hampered by the effect of wind on the combustion gain. Therefore, this paper combines the plume function with the backlayering length and critical backflow velocity to explore the plume shape, optimize the ventilation environment, and decrease its combustion gain in which shows three key features that include the concavity and convexity characteristics, instability of plume, and the balance feature. Moreover, through their derived five plume shape constraints, we acquire the optimal wind environment. Furthermore, we found that the expected length is 0.12 in optimal condition when the original critical velocity is larger than 0.43, and the other cases are 0.05 for expected length. Meanwhile, the ventilation velocity needs to be increased three to seven times. The study provides new insight into the plume flow under the wind environment and would accelerate the formalization of fire protection design for utility tunnel.     

Horizontal cable tray fire in a well‐confined and mechanically ventilated enclosure using a two‐zone model

Electrical cable trays are used in large quantities in nuclear power plants (NPPs) and are one of the main potential sources of fire. A malfunction of electrical equipment due to thermal stress for instance may lead to the loss of important safety functions of the NPPs. The investigation of such fires in a confined and mechanically ventilated enclosure has been scarce up to now and limited to nuclear industry. In the scope of the OECD PRISME‐2 project, the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) conducted more than a dozen fire tests involving horizontal electrical cable trays burning either in open atmosphere or inside mechanically ventilated compartments to investigate this topic. A semi‐empirical model of horizontal cable tray fires in a well‐confined and mechanically ventilated enclosure was developed. This model is partly based on the approach used in FLASH‐CAT and on experimental findings from IRSN cables fire tests. It was implemented in the two‐zone model SYLVIA. The major features of the compartment fire experiments could then be reproduced with acceptable error, except for combustion of unburned gases. The development of such a semi‐empirical model is a common practice in fire safety engineering concerned with complex solid fuels.     

Fire spread from an open‐doors electrical cabinet to neighboring targets in a confined and mechanically ventilated facility

Electrical cabinet fire is one of the main fire hazards in nuclear power plants. As part of the OECD PRISME‐2 programme, four fire tests were carried out to investigate the fire spread from an open‐doors electrical cabinet to overhead cable trays and adjacent cabinets in a confined and mechanically ventilated facility. These tests, named CFS‐5 to CFS‐7 and CORE‐6, used same both cabinet (fire source) and three overhead cable trays. The trays were filled with a halogenated flame‐retardant cable‐type for CFS‐5 and one halogen‐free for the three other tests. Moreover, fire dampers were used for CFS‐7 test while CORE‐6 test implemented two additional cabinets adjacent to the fire source. Measurements such as flame and gas temperature, gas concentration, mass loss rate, and heat release rate were performed for investigating the fire spread. Cabinet fire spread to the cable trays for CFS‐5 and CFS‐6 tests. Three fast and short cable tray fires were shown for CFS‐5, while a slow and long cable tray fire was highlighted for CFS‐6. In contrast, the fire dampers shutdown for CFS‐7 test prevented ignition of the overhead cables. Furthermore, for CORE‐6 test, cabinet fire spread to the adjacent cabinets, but the upper cables were not ignited.