Earthen Architecture in Seismic Zones:Latin America and the Pacific Fire Belt

This paper analyzes the current state of earthen constructions in countries located in the Pacific Ring of Fire.In Latin America,countries such as Colombia,Ecuador,Peru,Bolivia,Chile and Argentina are located in the Pacific Ring of Fire and are subject to strong seismic exposure,making earthen constructions more vulnerable.From an analysis of the housing censuses of each country,it was observed that currently,earthen construc­tion continues to be a construction option,that the percentage of earthen constructions varies from country to country,and that they make up a high percentage of dwellings;namely,in Colombia 5.3%(714.478 houses),Ecuador 8%(383.086),Peru 31%(2.390.625),Bolivia 37%(1.037.473),Chile 2%(121.756)and 1.9%in Argentina(230.185 houses).Peru,despite being one of the countries with the highest seismic risk,is the country with the highest number of earthen dwellings.It was concluded that in all the countries analyzed,earthen architecture prevails,employing different con­struction techniques whose characteristics are deeply rooted in each coun­try’s ancestral culture.This highlights the importance of having regulations in place and skilled workers in order to intervene correctly and repair the structures after a seismic event.

Applying BP neural network to detect conveyor belt fire with multi-sensors

A kind of feed forward neural network with three layers was applied to detect conveyor belt fire faster. And backward propagation (BP) algorithm was used to train the network parameters. The appropriate parameters and architecture of network were ob- tained after training with 81 pair of data. Matlab was used to simulate and the experi- ment result shows training time is least and error reduces most rapidly when ten neu- rons were in hidden layer and momentum coefficient is equal to 0.95. Temperature, rate of temperature change, dense of carbon monoxide and rate of carbon monoxide dense change were considered as four parameters to detect the PVC belt fire in this paper. It is indicated that the network can give alarm as fire takes place about 350 s. The network can effectively detect the fire at the early stage of conveyor belt fire. At the same time, the reliability of alarm can be increased and the anti-interference capability can be en- hanced when using this network.

Numerical simulation and disaster prevention for catastrophic fire airflow of main air-intake belt roadway in coal mine—A case study

Coal mine belt fire develops very rapidly and is difficult to control. If not suppressed quickly, a belt fire could easily lead to airflow disorder and undermine the ventilation system. However, belt fire can be prevented effectively by establishing fire airflow control system. In this work, the 5th belt roadway of Kongzhuang coal mine was taken as the object of investigation, where geometrical models of this roadway were established firstly. Then, based on mathematical model of fire smoke flow, the CO volume fraction, smoke density distribution, air temperature and pollutant velocity vector in the roadway before and after taking airflow control measures were simulated by using Fluent software. It can be known from the simulation that with the normal ventilation status in 5th belt roadway, the countercurrent of smoke does not happen when a fire occurs; the roadway's section is almost filled with CO at 10 m downstream from the fire source, and with air velocity getting stable gradually, the CO concentration reaches about 15 %. After taking airflow control measures, the effect range of temperature field which are harmful to the miners decreases from 69 m to 30 m; and the distance of the roadway fully filled with CO is 5 m farther than that before taking measures. Finally, according to the numerical simulation results and the actual condition of the belt roadway, the warning and automatic remote airflow control system with short-circuit method for the 5th belt roadway was designed to guarantee the safety production.

矿井带式输送机火灾烟流特性及其预警防控综述

为有效防控煤矿井下带式输送机火灾事故,保障煤矿工作人员的生命财产安全,系统分析矿井带式输送机火灾的起火原因、燃烧特性、烟流特性、监测预警技术及防治措施,并基于当前研究现状提出展望。结果表明:引发带式输送机火灾的主要原因是摩擦温升、电气设备故障及明火;研究带式输送机火灾燃烧和烟流特性采用的巷道火灾模型及数值模拟相关参数具有一定局限性,需综合考虑运输巷道实际工况及环境等参数;国内虽有针对带式输送机火灾的监测预警系统,但其尚有不足,需引入5G、大数据及人工智能等新兴技术予以完善,并结合硬件探测及人员管理等方面,健全煤矿带式输送机火灾防治体系,进而全面推动煤矿安全智能化建设。

大型储煤堆场全封闭改造的消防安全评估研究

针对既有储煤堆场因环保需要进行全封闭改造,导致其占地面积过大等问题,运用消防安全评估的方法,参考相关案例,从防火隔离带、安全出口、消防设施等方面进行优化设计,并采用FDS数值模拟软件,着重对不同煤堆间火灾热辐射及钢结构的安全性进行分析验证。结果表明:宽度大于12m的防火隔离带可确保着火煤堆不会引燃相邻煤堆;除部分空间净高较低的火源正上方位置外,其他区域均未达到钢结构失效的临界温度。建议距离煤堆较近,净高较低的钢结构承重构件采取防火保护措施。评估结果可为同类案例提供参考。

矿用胶带火灾危险性评价研究

为解决目前矿用胶带火灾危险性评价中存在的主观分析和单一指标问题,提出了一种基于熵权法结合灰色关联度法的矿用胶带火灾危险性综合评价方法。利用NBS烟密度测试箱、锥形量热仪分析矿用胶带火灾烟气的光透过率、燃烧热释放速率、生烟速率和CO生成速率等火灾危险性关键影响因素,并建立矿用胶带火灾危险性多层次评价指标体系,综合评价不同热辐射条件下矿用胶带的火灾危险性。结果表明:在50 kW/m^(2)的热辐射强度下,测试箱内的光透过率迅速下降,在70 s时降为0;与热辐射强度25 kW/m^(2)时相比,35 kW/m^(2)下的热释放速率峰值和总热释放量分别增加了29.06%和36.22%,生烟速率峰值和总烟产量分别增加了45.55%和31.54%,到达生烟速率峰值的时间缩短了92.59%;矿用胶带火灾危险性因素的权重排序为:燃烧危险(0.5216)>生烟危险(0.2522)>毒性气体危险(0.2261)。

矿用胶带和电缆燃烧特性试验研究

为了防范矿用胶带和电缆燃烧火灾,文章采用FTT锥形量热仪测试并研究了其燃烧特性,并使用火灾危险性指标进行分析。试验测试胶带、电缆外护套和电缆绝缘层在30、40、50 kW/m^(2)热辐射强度下的燃烧特性,建立了热释放速率经验预测模型。结果表明:热释放速率曲线在上升阶段和下降阶段分别呈现出幂函数和指数函数规律;热辐射强度的增大使材料热分解加快,燃烧反应历程缩短,点燃时间缩短,耐热能力变弱,火灾危险性增大。

西南喀斯特地区生物防火阻隔带建设初探——以贵州省毕节市为例

在现有森林防火建设基础上,毕节市紧紧结合国家政策导向、支持方向、资金投向,实施生物防火阻隔带建设,进一步提升和完善林火阻隔系统,补齐当前森林草原防火重要基础设施存在的突出短板,有效制止林火蔓延,减少森林火灾所造成的影响和损失,对西南喀斯特地区生物阻隔带建设,推进森林防火治理建设和发展具有重要作用。

细水雾抑制巷道胶带火灾蔓延模拟

为探索细水雾对矿井胶带火灾蔓延的抑制效能,利用FDS软件构建矿井胶带火灾模型。研究风速、细水雾粒径、喷头与火源距离等因素对细水雾抑制胶带火灾效果的影响机制,探究不同工况下巷道温度场分布规律与烟气流动规律。结果表明,细水雾可以有效抑制胶带火灾蔓延,一定范围内,火场温度和烟气浓度均随风速增大而减小,风速由1 m/s增加到2.5 m/s,温度下降率增加18.42%;火场温度和烟气浓度随喷雾粒径、喷头与火源距离减小而减小;雾滴粒径由200μm增加到400μm,冷却与阻烟效率降低35.20%、22.85%;喷头距离火源超过14.5 m,细水雾抑制效果明显减弱。通过增大风速、减小水雾粒径、缩小喷头和火源距离,可以提高细水雾降温阻烟效果,为开发巷道火灾细水雾应急处置技术与装备提供理论依据。

钢铁企业焦炉区域封闭通廊消防系统设计

现行规范和标准对封闭通廊的消防系统设计并没有提供合适的解决方法,基于这一现状,论文阐述封闭通廊增设消防系统的必要性及其火灾的成因和特点,结合具体工程中皮带输送机的运行特点及生产要求,分析并探讨针对钢铁企业焦炉区域封闭通廊的消防系统设计。

Analysis of underground fires in Polish hard coal mines

In the period of the first twenty years after World War II the number of fires in Polish hard coal mines reached annually the value of several thousands of cases. About 80% of fires constituted spontaneous fires. Investigations into the development of new methods of fire hazard prediction and implementation of new methods and means of fire prevention as well as the introduction of prohibition concerning the use of products manufactured of combustible organic materials in underground mine workings re-duced considerably the hazard of underground fire rise. The worked out at the Central Mining Institute (GIG) new method of un-derground fire prediction allows the correct selection of fire prevention means. The introduction into common use of fire-resistant conveyor belts, the main factor giving rise to spontaneous fires, and methods of assessment of their fire resistance eliminated prac-tically the fire hazard. These activities contributed in an efficient way to the reduction of the number of underground fires to a sat-isfactory level.

Experimental Study of Kinetic Properties of Pyrolysis for Conveyor Belt in Coal Mine

The combustion of conveyor belt is a leading factor of mine fire. In this paper, the pyrolysis properties of ordinary conveyor belt and fire-resistant belt were studied experimentally with thermo-gravimetric analysis and derivative thermo-gravimetric analysis, and the curves of pyrolysis properties were achieved. On this basis, the activation energy and reaction order of pyrolysis were obtained in combination with theoretical analysis, aiming to provide data for further numerical simulation and simulating experiment of mine fire.

煤矿运输胶带热解动力学参数研究

为构建矿井胶带火灾早期预警体系,防控巷道外因火灾事故,利用热重—傅里叶红外光谱联用实验,结合热解动力学,研究5、10、15、20 K/min 4种升温速率下胶带的热解历程。结果表明:不同升温速率下的热重(TG/DTG)曲线、气体产物等具有相似规律和趋势,随升温速率增加各参量特征值向高温方向滞后;胶带热解经历2个明显失重阶段,第一失重阶段发生交联缩聚热解反应,活化能E在105~107 kJ/mol,指前因子为15.92 min^(-1),第二失重阶段发生脱链解聚热解吸热反应和挥发分氧化放热反应,活化能E在130~220 kJ/mol,指前因子为37.13 min^(-1),高于第一失重阶段,两阶段热解过程可用Avrami-Erofeev方程表征。

逊克县森林防火可燃物管理和阻隔系统建设技术研究

加强林火阻隔系统建设可以起到防火、阻火作用,降低森林火灾发生率和有效阻隔林火大范围蔓延,发挥绿色防火手段的长效性和多效性。通过对逊克县林区基本概况分析,合理区划林火阻隔网格,提出改造防火通道、改培防火林带,提出森林可燃物和使用机械设备处理森林可燃物的具体森林可燃物管理与林火阻隔系统技术措施,变被动防火为主动防火、变消费型防火为生产效益型防火,为改培生物防火林带系统建设的展开全面提供借鉴和参考意见。

木荷防火林带研究进展

简述了木荷防火林带在森林防火中应用历史背景、发展历程和重要意义。通过长期调查、监测木荷防火林带林分因子,分析防火林带经济效益和局限性,提出建设多功能防火林带的思路,为新时期森林防火工作提供决策参考。

防火隔离带在轨道交通换乘枢纽中的应用探究——以深圳市岗厦北综合交通枢纽为例

随着轨道交通发展,轨交线路成为城市空间网络的主要动脉,也由单一站点向多线交织甚至多种交通方式换乘的趋势发展。这种大型枢纽公共空间如何在保证枢纽公共空间连续、通透的前提下,将防火分区划分为若干防火单元,降低火灾危险性成为大家关注的重难点之一。通过实例论证提出用防火隔离带划分防火单元的方法,并提出防火隔离带设置的相关建议。

海南霸王岭生物防火林带物种多样性调查研究

为探究海南热带雨林国家公园生物防火林带群落结构和生物多样性特征,以公园内霸王岭生物防火林带为调查对象,分析生物防火林带群落径级和高度级分布特征,以树种重要值、物种丰富度指数(D)、Simpson优势度指数(H)、Shannon-Wiener多样性指数(H′)、Pielou均匀度指数(J_(sw))综合评价生物防火林带群落优势树种和物种多样性。结果显示:(1)生物防火林带植物种类有27科34属35种;(2)群落结构在径级和高度级方向分布均为连续;(3)造林树种大叶相思重要值偏低,群落优势度不突出;(4)乔木层和灌木层物种多样性较高,物种分布较均匀,乔木类树种物种多样性明显高于灌木类、藤本、草本植物。霸王岭生物防火林带生物多样性较高,物种分布较均匀,群落层次结构明显,群落更新状态良好,但防火树种优势度不突出。

带式输送机火灾预警及自动灭火系统的设计及应用

针对华阳一矿北翼第一部带式输送机运煤路线较长,带式输送机存在安全隐患的问题,设计了一套带式输送机火灾预警及自动灭火系统,根据该条带式输送机的具体情况,对于不同区域进行针对性处理。介绍了火灾预警及自动灭火系统的主要组成,对具体实现形式进行了分析研究,并对现场施工进行了设计。实践表明,北翼第一部带式输送机火灾预警及自动灭火系统可以有效监控带式输送机各机构的温度,实现快速定位火情并自动灭火,应用效果良好。

隧道洞口大跨度全封闭声屏障自然排烟效率研究

为明确大跨度全封闭声屏障侧部排烟的可行性,得到易熔采光带开口率对设置侧部自然排烟口声屏障排烟效率的影响规律,采用缩尺寸模型实验和数值模拟方法研究了最不利排烟车道(F车道)、常年环境风(3m/s)和易熔采光带开口率等场景下声屏障自然排烟效率。结果表明:侧部自然排烟口能保证烟气的有效排出;常年环境风和易熔采光带开口率对声屏障总排烟效率无太大影响;易熔采光带排烟效率与其开口率呈现负一次方关系,推荐易熔采光带开口率为10%左右。