被引排行
On the urban subway construction safety risk assessment based on the rough set and RBF neural network
CHEN Fan1,XIE Hong-tao2(1 School of Civil Engineering,Hunan University of Science and Technology,Xiangtan 411201,Hunan,China;2 Construction Engineering College,Kunming University of Science and Technology,Kunming 650093,China)The present article is inclined to bring forward an urban subway construction risk assessment based on the rough set and RBF neural network.As is known,it has become urgent to promote the safer and more securable subway construction environment with the current surge of subway construction tide in China.In this article,we would like to propose a subway construction risk assessment model based on the analysis of subway construction safety risk assessment model including indicators,which we have chosen of 33 variables in the light of geological conditions,the construction technology,management and so on.In order to overcome the drawbacks of the traditional artificial neural network,namely,slow convergence,poor fault tolerance and inconsistent results,we prefer to choose the rough set method,intending to reduce the table attribute of the sampling decisions and decrease the amount of irrelevant index inputs of the neural network data.The rough set method also allows us to do training and testing on how the given RBF neural network model can be used together with the rough set method by means of the actual subway construction project data.Practically speaking,we have already gained the above said survey data from the 28 subway construction practice from the field project experience in eight cities,that is,from Wuhan,Changsha,Hangzhou,Kunming,Beijing,Shanghai,Guangzhou and Chongqing.The results of our analysis of the data quoted show that the data input with the RBF neural network can actually be reduced from 33 to 15 by using the rough set method.After reducing the sampling data through the rough set method,the sampling sets can be used as the training sets of the RBF neural network.The RBF neural network structure can be effectively simplified with the training steps and training time decreased,and the network training and learning speed and efficiency can be greatly improved.And,as a result,the convergence speed and the calculation accuracy can be easily made to meet the requirements of the subway construction safety risk assessment through the attribute reduction.Therefore,it can be seen that this present coupling of the rough set method and RBF neural network system can be surely taken as the safety state guaranteeing means along with the relevant safety technology for the urban subway construction.
Study on the risk rank indices of hazardous materials transportation
REN Chang-xing~1,WU Zong-zhi~2(1 College of Environmental Science and Engineer,Nankai University,Tianjin 300071,China;2 China Academy of Safety Sciences and Technology,Beijing 100029,China)As a rule,hazardous material(Hazmat) transportation is regarded as a kind of linear transferring hazard source due to a lot of random and unexpected factors even among the experts.This paper is aimed to present a risk rank index method based on the study of hazmat characteristics and risk factors involved, such as the hazmat risk rating index,impacted factors of route and safety precaution compensated factors.Actually,hazmat risk rating index is based on the hazmat inherent hazard features,including the health-threatening hazard,flammability hazard,reactivity hazard and special hazard,and quantity of hazmat,habitation distance as well as dispersion factor at 5 ranks.The route-impacting factors may consist of road quality,weather condition,traffic condition and population distribution along with the safety precaution compensated factors.The method introduced here can be applied to assess the hazard potential of hazmat transportation quickly and conveniently and therefore can be taken as a supportive safety measure in transportation practice.
Empirical study on the effect of safety atmosphere on the safety performance in the construction enterprises
SUN Jun;YAN Sen;DU Chun-yan;School of Civil Engineering & Mechanics,Huazhong University of Science and Technology;This article is aimed to engage in an empirical study on the effect of safety atmosphere on the safety performance in the construction enterprises. It is a common idea that the behavior and performance of employees is of great importance to an enterprise,so is the safety and stability of the working environment to thequality and efficiency of an enterprise. In order to disclose the working principle and relation between the safety atmosphere and the employees' safety behavior,this paper has chosen such items as the management commitment,the working environment,the safety awareness as three dimensions of the safety atmosphere for our analysis. In doing so,we have established a structural equation model( SEM) by the actual data we have collected and testing it empirically. For our research purpose,we have been to distinguish engineering departments and done investigations through questionnaire,and,then recycled the effective questionnaires,in addition to organizing related data. While analyzing the data,we have adopted softwares named SPSS 19. 0 and AMOS 17. 0. The other related research forms we have mainly undertaken include: the reliability analysis,the validity analysis,the structural equation modeling analysis,and the mediation effect analysis. The analysis results of our investigation indicate that the working environment and safety consciousness have direct and positive influence on the safety behavior. The standard path coefficient of the working environment on the safety behavior proves to be 0. 623,while the standard coefficient of the safety awareness on the safety behavior turns to be 0. 350. What is more,the management commitment also proves to play a vital role in creating the safety atmosphere,and affects the safety behavior positively through the working environment and safety awareness.Thereinto,the working environment accounts for the 63. 93% influence of the management commitment on the safety behavior,whereas the safety awareness accounts for 35. 42% influence of the management commitment on the safety behavior.
On the basic characteristic features and incidental regularity of coal and gas outbursts in China since from 2001 to 2012
LI Bo1,2,WANG Kai1,2,WEI Jian-ping1,TIAN Tao2,LI Peng2(1 State Key Laboratory Cultivation Base for Gas Geology and Gas Control(Henan Polytechnic University),Jiaozuo 454000,Henan,China;2 Faculty of Resources and Safety Engineering China University of Mining and Technology,Beijing 100083,China)This article is aimed at making a research review of the basic characteristic features and incidental regularity of coal and gas outbursts in China since 2001.So far as we know,among the 417 accidents of coal and gas outbursts that have ever taken place in China since 2001 we have statistically analyzed,two basic characteristic features can be summarized of such outburst accidents in the country at the present stage.So far as we have got to know,the causes leading to such outburst accidents can be classified into two basic categories,according to the outburst frequency and according to the death tolls.From the two aspects of the regularity of gas outbursts,the accidents in China after 2001 were directly displayed in a variety of graphical ways,such as in a pie chart,histogram,trends,and rings.The statistical results show that there has been a greater accident frequency in the south than that in the north of China.As a matter of fact,Hunan and Guizhou are the places with the most frequent and serious coal mine accidents in the country,followed by Chongqing,Sichuan,Henan and Yunnan.Among them,large,serious accidents account for 62.11% of the total number.If accounts go on according to the death rolls and number of death,46% of the total death attributes to the greatest cases of casualty,though,the particularly serious coal-mine accidents occur less frequently,only about 2.39% of the total.But the death toll is much greater,accounting for 19.90% of all the casualty.If the comparison goes on between the coal and gas cases,more accidents of the gas outbursts take place of the two,the causes of which are consistent with the first class of basic characteristics.The causes leading to the outbursts in the high gas mines not only are in accordance with the first class of basic characteristics,but also come in line with the second class of basic characteristics in terms of management and exploitation.
CFD NUMERICAL SIMULATION OF GAS DIFFUSION
JIN Ying,ZHOU Wei-guo & RUAN Ying-jun (Department of Thermal Energy Engineering, Tongji University, Shanghai 200092, China)As is known, gas diffusion has been a headache troubling environmental scientists. Though tremendous progress has been gained for centuries in their work, most of research has been done based on Gauss plume model that was done on the normal school hypothesis and thus limited its results. To improve the research of gas diffusion, this paper has reviewed and analyzed a series of equations, such as continuity equations, momentum equations, energy equations and species transport equations. It has been found in the work of the authors that the above equations were dispersed in nature and turbulence model had to be used for their solution. To solve such problems in a new way, they have tried a new method known as CFD Numerical Simulation of Gas Diffusion. After simulating gas diffusion in a small size and the simple condition, the authors analyzed the relation of gas diffusion to air velocity, fume velocity and fume temperature. And then the result of the analysis has also been analyzed and compared with Gauss plume model, which proves the feasibility of the new method. And finally, the authors have brought about some ideas on the insufficiency of the above method and corresponding suggestions on how to improve on it in the future.
Safety risk assessment for the railway gas tunnel construction based on the fuzzy-entropy method
WU Bo ;CHEN Hui-hao ;HUANG Wei ;The aim of this research is to assess the construction risk of the railway gas tunnels, whose construction has been on account of risks in a great variety. For instance, its construction involves lots of complicated influential factors in addition to the uncertainty and unexpected construction liabilities. It is just due to the above mentioned and lots of other unexpected reasons that the given paper intends to devote itself to make a detailed analysis in combination with a case project which involved lots of factors influencing the construction safety. And, then, based on the above said factors, we have managed to build up a safety risk assessment system for the railway gas tunnel construction procedures, with the quantitative range of gas tunnel construction risk assessment indexes carefully given. At the same time, we have also done a careful analysis of the assessment and scoring records for each factor of the safety risk assessment system of the said railway gas tunnel construction offered by the above said esteemed experts. Moreover, the weights of the factors at the various levels have also been reviewed and determined via the entropy method. Besides, the fuzzy mathematic model has also been taken to assess each factor bit-by-bit comprehensively, so as to gain the risk rating of the gas tunnel construction firmly. And, finally, we have managed to establish an assessment set to determine the risk rating spheres of the railway gas tunnel construction. The final conclusions have been made as follows:(1) The fuzzy entropy weight method is capable to solve the problem of the fuzzy assessment of the multiple influential factors through quantitative calculation, whereas the conclusive risk assessment of the railway gas tunnel project is definite, reasonable and qualified enough to guarantee the effective going on for the gas tunnel construction; And,(2), it is necessary for the successful construction safety to demand a strict and qualified supervision and control of key factors, such as the adjacent coal mines and the oil and gas fields, the lithological factors, the tunnel depth, the deadline limit of the coal mine tunnel construction into exploitation, the technical literacy of the operators, the geological exploitation factors and groundwater control, plus the coordination of other secondary affecting factors; And,(3) There exist potential risks of the railway gas tunnel construction accident, which has been assessed as level 3. And, so, the calculation results we have done prove to be in line with the actual project, with the similar projects taken for reference. And, therefore, the fuzzy-entropy method theory has been made adopted effectively and successfully to the risk assessment of the railway gas tunnel construction.
Risk assessment of the deep foundation pit based on the entropy weight and 2-dimensional cloud model
WANG Jing-chun;ZHANG Fa;College of Civil Engineering,Shijiazhuang Tiedao University;The paper is inclined to present a comprehensive risk evaluation method based on the entropy weight method and2-dimensional cloud model for evaluating the risk of the deep foundation pit in the construction of Qingxiushan station of Nanning Metro Line 3. For this purpose,we have,first of all,been trying to identify and determine the risk factors from the 3 closely related factors, that is, the factors in environment,management and construction. In doing so, we have established 12 second level evaluation indicators via refining the first level indicators,and an evaluation index system for the construction risk with the deep foundation pits. Furthermore,we have also built up the effective linkage between the risk grade and the 2-dimensional cloud for evaluating the risk probability and the risk consequence severity through defining the basic variables of the 2-dimensional cloud. The weights of evaluation indexes gained with the entropy weighing method can help to reflect the influential degrees of the respected indexes on the evaluation objectives. Furthermore,the digital features of the risk cloud and the weight cloud gained by the back-sequential cloud generator and the integrated risk cloud matrix derived by the weighing operation can help us to work out the cloud matrix and that of the risk cloud so as to gain a comprehensive risk picture by the normal cloud generator with the aid of the MATLAB software. And,eventually,we have proposed the similarity degree of the risk clouds to determine the risks of the foundation pits. Thus, the aforementioned methods prove to be suitable for assessing the construction risks of the foundation pit of Qingxiushan station of Nanning Metro Line 3,by properly calculating the grades of the entire foundation pit project and evaluation indexes at all levels,which is well in accord with the actual project situation. Hence,the final results show that the risk assessment method based on the entropy weight and the 2-dimension cloud model can effectively solve the fuzziness and randomness of risk evaluation indexs,take into the influence of evaluation index weight on evaluation results,and realize the transformation between qualitative concept and quantitative expression of risk grade,which evaluation result is more intuitive and reliable.
Characteristics and sources of PM2.5 in typical atmospheric pollution episodes in Beijing
WANG Zhi-juan1,HAN Li-hui1,CHEN Xu-feng2,CHENG Shui-yuan1,LI Yue1,TIAN Chuan1,XIE Hui1(1 College of Environmental & Energy Engineering,Beijing University of Technology,Beijing 100124,China;2 Tangshan Environmental Monitoring Station,Tangshan 063000,Hebei,China)To study the characteristics and sources of PM2.5 in typical atmospheric pollution episodes during winter and spring in Beijing,the samples of PM2.5 were collected at the air quality monitoring site during winter and spring from 12/2010 to 03/2011.The periods are typical seasons for two types of heavy air pollution,i.e.haze and dust to happen often.Concentration of PM2.5,elements,water soluble ions and organic and elemental carbons of PM2.5 were analyzed for typical haze,dust,unpolluted weather during winter and spring.The results indicated that daily concentrations of PM2.5 during haze and dust days were up to 301.8 μg/m3 and 284.8 μg/m3,that were 8.62 and 8.14 times of the daily standard of EPA.Enrichment factor method was used to analyze the natural sources or anthropogenic sources of different elements during non heavy air pollution periods.Polluting elements S,Cu,Zn,As,Se,Cd,Sb,Pb were mainly released from coal combustion,motor vehicle exhaust and waste burnt;while Na,Mg,Al,Ca,Fe were main crustal elements.NH+4,NO-3,SO2-4 were found to be the dominant ionic species of PM2.5.The value of OC/EC(4.085) exceeded 2 suggesting that the OC of Beijing during haze belongs to secondary pollution source.Concentrations of anthropogenic source elements S,Cu,Zn,As,Se,Cd,Sb,Pb in PM2.5during haze were higher than that of unpolluted weather and dust.The concentrations of secondary inorganic particles NH+4,NO-3,SO2-4 and secondary organic carbons of PM2.5 during haze were higher than that of another two types of weather.Concentrations of crustal elements Na,Mg,Al,Ca,Fe during dust days were higher than that of unpolluted weather and haze.PM2.5 were mainly released from coal combustion and industry,secondary reaction,soil,motor vehicle and waste burnt during winter and spring.Contribution of secondary reaction was higher than other sources during haze,while contribution of soil was higher than others during dust.
On route-choice analysis of hazardous materials transportation
REN Chang-xing1, WU Zong-zhi2 (1 Urban Public Safety Research Center, Nankai University, Tianjin 300071, China; 2 China Academy of Safety Science and Technology, Beijing 100029,China)This paper intends to introduce the author's analysis on the general framework of hazardous materials (hazmat) risk during the road transportation that may be caused by the route choice, the vehicle or traveling risk source and the impact area. It has mainly discussed the route-independent and route-dependent factors, including the factors correlated to intrinsic road characteristics, meteorological conditions, traffic characteristics and the population density. As is known, the risk analysis is of the premise to the hazmat optimal routing, which is of utmost importance both to the decision-making of government and the carrier itself. The present paper has also discussed the importance of the bi-level routing management model while giving a detailed analysis on the possibilities to minimize the accident probabilities and population exposure models. And, in final analysis, the hazmat routing problem can be resolved with impedance-adjusting node-labeling shortest path-selection algorithm and link-labeling shortest path-selection algorithm. Moreover, a detailed study on the population exposure zone has also been done, taking full account into the error terms of the overlaps between adjacent links, which is also worthy of careful calculation.
Research review on acceptable risk level for dam safety assessment
XIAO Yi, GUO Sheng-lian, XIONG Li-hua, LUO Zheng(State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China)This paper aims to present the author's study on the acceptable risk level for dam safety assessment. As is known, it is of primary importance to guarantee the safety of dams because it involves public safety, social welfare and its sustainable prosperity. The so-called acceptable risk level refers to the threshold for the safety level based on the risk analysis and assessment. To make our study and approach as feasible as possible, the present authors have made a systematic revision of the literature and materials available both at home and abroad in this connection. As a result, it has been found that measures to be taken to prevent the risk of dams are to be built on the basis of the risk evaluation. In terms of the consequence of the failure, such risks can be categorized into a few types, to which risk measures are to be taken respectively. For this purpose, the paper mainly defines the acceptable risk levels for the corresponding risk-prevention measures, including failure probability and the consequences of measure failure, such as human casualty (individual and societal risk) and economic loss, etc. In addition, the acceptable risk rates of the dam are also briefly described in the paper. In more detailed way, the paper has discussed the methods to use ALARP (As Low As Reasonable Practicable) principle and F-N (relationship between the annual probability of an event causing N or more fatalities, and the number of fatalities N) curve so as to determine the acceptable risk and their applications in the area of dam safety assessment. Of course, it is necessary to decide acceptable risk levels and then choose the reasonable risk measures according to the risk analysis of the dam safety. However, it remains a controversial issue to make accurate assessment of the acceptable risk level in the actual situations, which is still left be solved through the joint efforts of the governmental departments, engineers, scholars and the public concerned.