China Safety Science Journal

Study on PSI and PeSI during heat acclimatization training in high-temperature environment

ZENG Pu, ZHU Neng

2017, 27(11): 1-6. doi:10.16265/j.cnki.issn1003-3033.2017.11.001

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To investigate the changes of PSI and PeSI during heat acclimatization training and the relationship between them, heat acclimatization training in high-temperature environment was carried out by using a climate chamber. 16 healthy male college students were taken as testees, they were randomly assigned to test under different conditions consisting of different temperatures and labor intensity,and PSI and PeSI in subjects were calculated. The differences of PSI and PeSI before and after heat acclimatization training were analyzed by paired sample t-tests. The variance analysis method was used to analyze the influences of temperature and labor intensity on the PSI and PeSI. The relationship between PSI and PeSI was studied by correlation analysis and regression analysis. The results demonstrate that heat acclimatization training can reduce the PSI and PeSI of testees and the key factor influencing the PSI and PeSI is the labor intensity at the time of training, that PSI can be predicted by PeSI, but the prediction accuracy varies with the working condition, when the temperature is 36～38 ℃ and the relative humidity is 50%, the prediction accuracy of PSI under heavy labor intensity condition is greater than that obtained under the moderate intensity condition.

Conceptual model for individual safety information force and its action mechanism

HUANG Lang, WU Chao, WANG Bing

2017, 27(11): 7-12. doi:10.16265/j.cnki.issn1003-3033.2017.11.002

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In order to perfect the theoretical system of safety information cognition, this paper was aimed at building a conceptual model of individual safety information force and studying its action mechanism. Firstly, the concepts of individual capacity and individual safety capacity were discriminated, and then, based on engineering psychology and cognitive psychology, by using the inductive approach, a concept of individual safety information force was put forward, its connation and characteristics were analyzed. Secondly, the conceptual model of individual safety information force was built, which consists of safety informationacquisition ability, safety information analysis ability and safety information utilizing ability. Lastly, the relationship between individual safety information force and individual behavior was analyzed, based on this, the action mechanism of individual safety information force was argued from three aspects, which are the size, direction and function point of individualsafety information force. Research results show that the essence of individual safety capacity is individual safety information force, the construction of individual safety information force conceptual model and the analysis of its action mechanism can reflect the essence of individual safety capability.

Research on wireless and composite signal system for high-rise building fire accurate alarm

ZHANG Lining, AN Jing, ZHANG Lihua

2017, 27(11): 13-17. doi:10.16265/j.cnki.issn1003-3033.2017.11.003

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In order to effectively prevent and control the high-rise building fire accidents, a signal system was developed for high-rise building fire accurate alarm on the basis of the latest wireless communication and composite signal technology. In view of the limitation of existing building fire auto-alarm systems, before developing the system, a construction idea was put forward for a wireless and composite signal system. Then the hardware and software problems of system implementation were solved through the study of data acquisition terminal, the sub-station node and the alarm algorithm. On this basis, a fire experiment platform was built to test and experiment the system. The research shows that the system has good reliability, can sound the alarm more timely and accurately than other single signal systems, and in the experiment, it trips the alarm over 2 s earlier than other single signal systems do, and the false alarm rate is less than 2%.

Study on lithium-ion batteries' fire characteristics and trace identification technology

ZHANG Yi, WANG Lifen, LYU Zhong, YANG Shiqun, PENG Bo, ZHAO Changzheng

2017, 27(11): 18-23. doi:10.16265/j.cnki.issn1003-3033.2017.11.004

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In order to investigate the fire characteristics of lithium-ion battery under different fault conditions, puncturing, external heating, and overvoltage charging experiments were carried out on several common lithium-ion batteries of electric vehicles. Melted marks caused by the battery combustion were investigated as well. The results show in the puncturing and external heating experiments, both temperature rise and toxic gas release level of the ternary materials lithium-ion battery are higher than those of any of both the LiCoO₂ lithium-ion battery and the LiFePO₄ lithium-ion battery. In the overvoltage charging experiments, the ternary materials lithium-ion battery is easy to give out heat, and its surface temperature increases quickly, showing an obvious fire risk. The heat produced by the battery combustion can melt the iron shell. And the metallographic structures of the melted mark presents the characteristic of arc trace. That the metallographic structures of metal shell grow, presenting an uneven distribution.

Study on influence of smoke barrier on smoke temperature distribution under ceiling in long channel

WANG Huan, QI Qingjie, ZHOU Xinhua, WU Xian, JIANG Haiyang, ZHAO Youxin

2017, 27(11): 24-30. doi:10.16265/j.cnki.issn1003-3033.2017.11.005

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In order to improve the smoke blocking performance, and reveal the role of smoke barrier in smoke control of long channel, numerical simulations were carried out. The distribution of hot smoke temperature near the ceiling was studied with the distance between smoke barrier and fire source being 4.2, 6, 9 and 12 m, respectively, as well as the height of the smoke barrier varying within the range of 0-0.9 m. A longitudinal temperature distribution predictory formula was obtained for smoke flow in downstream of smoke barrier through the data fitting method. The formula was validated by 1∶5 scale channel fire experiments. Results show that the influences of the smoke barrier on the attenuation of the smoke temperatures in the upstream and downstream are respectively slow attenuation and accelerated attenuation, that with the increase of the barrier height, the temperature rise increases in the upstream region, while decreases in the downstream region, that height of the smoke barrier and the attenuation rate of the downstream temperature has a linear relationship, that the farther away from the fire source, the larger the dangerous range of high temperature smoke will be, and that the formula prediction results conform with the temperature data measured, which demonstrates the effectiveness of the reliability of the simulation model.

Experimental study on domino effect in pool fire in tank farm

CHEN Fuzhen, ZHANG Mingguang, WANG Yan, LIU Fuqi, SONG Jian, ZHENG Feng

2017, 27(11): 31-36. doi:10.16265/j.cnki.issn1003-3033.2017.11.006

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To study the damage of domino effect in pool fire in tank farm to the surrounding personnel and the adjacent tanks, three large scale pool fire tests were done by using 180# fuel oil. The measured temperatures were converted to the thermal radiation values, and a comparison was made between them and the theoretical calculation values. According to the measured mean thermal radiation and the personnel injury curve, the injury of thermal radiation to the surrounding personnel was analyzed. Finally, on the basis of both the experimental results and the theoretical analysis, the damage probabilities of adjacent tanks were obtained. The results show that both the speed and the direction of the wind affect combustion of fire, affecting the propagation of heat radiation accordingly i.e. the greater the wind speed is, the greater the received thermal radiation intensity at the downwind will be, that the more unstable the wind velocity is, the greater the thermal radiation fluctuation will be, that when the thermal radiation intensity is large enough, the personnel may suffer serious injuries in a short exposure period even at a long distance from fire, that pressure tanks are more prone to secondary accidents than atmospheric tanks, and that in order to prevent the occurrence of domino accidents, priority should be given to cooling down the pressure tanks at the downwind.

Predicting research on characteristic parameters of blast-induced vibration based on optimized IGA-ELM model

WEN Tingxin, CHEN Xiaoyu, LIU Tianyu, LIU Xu

2017, 27(11): 37-42. doi:10.16265/j.cnki.issn1003-3033.2017.11.007

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To predict the characteristic parameters for blasting vibration of open-mine effectively, an optimal IGA-ELM model was built on the basis of combination weighting. Before building the model, the parameters of input layer was determined in line with the influence factors of blasting vibration. And that of output layer were confirmed according to the safety regulation criterion for blasting. Then, the subjective and objective weights obtained by fuzzy analytic hierarchy process (FAHP) and entropy weight method respectively were integrated by applying the harmonic mean concept. And the weights of input layer parameters were quantified. In addition, IGA was introduced to select the input layer weights and hidden layer deviations of ELM by optimization. The optimal node number of ELM hidden layer was explored by using the stepwise increase-decrease method.The model was applied to a certain open-mine in China.The research results show that the optimal IGA-ELM model can be used to predict the characteristic parameters for blasting vibration of strip mine more accurately, and that the mean square error, determination coefficient, and simulation error are superior to those obtained by other models.

Experimental study on secondary explosion of aluminum powder in elbow pipeline and its suppression

LEI Weigang, BI Haipu, WANG Kaiquan

2017, 27(11): 43-48. doi:10.16265/j.cnki.issn1003-3033.2017.11.008

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A laboratory system was used to test and study the key parameters of dust explosion and its suppression, as well as to analyze the effects of elbow pipeline on propagation and consequences of primary and secondary aluminum dust explosions. The secondary dust explosion of the aluminum powder was triggered by the shockwave from propane explosion. The explosion process and its suppression were then tested in the elbow tube accordingly. Results show that the pressure of the secondary dust explosion of aluminum powder blowed by shockwave was obviously higher than that of pure propane explosion, and the maximum pressure appears at the concentration of 500 g/m³. Both the propagation time and flame intensity are reduced significantly by adding anti-explosive agent, and ammonium dihydrogen phosphate is better than calcium carbonate in suppression effect.The explosion pressure decreases with the addition of ammonium dihydrogen phosphate and when the suppressant's mass fraction is 10%, the explosion is suppressed completely.

Thermodynamic study on explosion mechanism of 7-ACA dust

XIE Qihang, ZHANG Jinfeng, LI Yanli, ZHENG Yanmin, WANG Hao, LIU Xiaokai

2017, 27(11): 49-54. doi:10.16265/j.cnki.issn1003-3033.2017.11.009

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7-ACA dust has a risk of explosion in the production process. In order to study the explosion mechanism of 7-ACA dust, experiments were carried out by using TGA method. Heating rates of 10, 20 and 30 ℃/min were used in the experiments. Experiments show that the minimum fire temperature of 7-ACA dust is 220 ℃ at the rate of temperature increase being 10 ℃/min, that the higher the rate of temperature increase is, the higher both the minimum fire temperature and the temperature corresponding to the maximum weight loss rate will be, that for the cracking stage, the activation energy is 7.347 kJ/mol, the pre-exponential factor is 1.4×10⁷ and the reaction is 1.5 a order reaction, that for the combustion stage, the activation energy is 146.99 kJ/mol, the pre-exponential factor is 9.18×10¹¹ and the reaction is a 2 order reaction, and that the values of thermal dynamics parameters are not high for the whole process and 7-ACA dust can be ignited with a small amount of energy and poses a risk of explosion.

Analysis of failure probability of vertical tank under debris flow impact

CHEN Guohua, ZENG Tao, YANG Yunfeng, TIAN Zhen

2017, 27(11): 55-60. doi:10.16265/j.cnki.issn1003-3033.2017.11.010

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In order to assess the risk of Natech accident triggered by debris flow and quantitatively analyze the influence of debris flow impact on vertical storage tank, a simplified mechanical model was built for the tank under the action of debris flow. The failure modes were divided into four categories: bending failure, tank instability, tank floating and tank slipping. Based on this classification, four groups of limit state equations were constructed. On the basis of Bayesian network and the reliability theory, a calculation method of failure probability for tank was worked out. The method was used to analyze and calculate an accident scenario. The results show that the failure probability of the tank is 81.19%, and that increasing filling rate of tank and reducing the aspect ratio of large storage tanks can prevent the accident in areas prone to the debris flow.

Study on Hadoop platform based method for gas outburst prediction and early warning

HAO Tianxuan, ZHANG Chunlin

2017, 27(11): 61-66. doi:10.16265/j.cnki.issn1003-3033.2017.11.011

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In order to prevent coal and gas (methane) outburst accidents, this paper was aimed at working out a method for prediction and early warning of coal and gas outburst based on Hadoop platform. Firstly, the Holt exponential smoothing method was used for preprocessing the gas concentration monitoring data in real time, so as to improve the accuracy and integrity of the monitoring data. Secondly, characteristic parameters of the gas concentration were extracted based on the BP neural network model. A gas outburst prediction and early warning model was built on the basis of both characteristic parameters extracted and the outburst prevention detection data. Finally, field application of the method was made at the Wu9-10-21050 working face of Pingdingshan No.8 mine. The results show that the method can be used for dealing with and analyzing large quantities of gas concentration data, improving the reliability of both the prediction and the early warning.

Research on model for collision risk in process of airspace planning

QU Yuling, HUO Zhiqin, LI Chong, ZHU Xinping, CHEN Yanli, QU Yanwei

2017, 27(11): 67-72. doi:10.16265/j.cnki.issn1003-3033.2017.11.012

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To provide an operational collision risk calculation method to be used in the process of airspace planning, the collision risk per flight hour on flight segment was researched. The existed models were improved based on airspace planning parameters. Firstly, collision risk was analyzed when the angle between two flight segments changes from zero degree to 180 degrees in terminal area airspace and on the air-ways. Secondly, the collision risk on flight segment was expressed by the sum of the collision risk stemming from this flight segment, the other risk stemming from other flight segments,and a collision risk model was built. Finally, when the values of the parameters related to terminal area airspace planning were input into the model, collision risks of two situations were calculated, and changing trends of collision risk with parameters were analyzed. The results show that when other parameter values are given, the collision risk will increase with the increasing Required Navigation Performance value, altitude (decreasing nominal vertical distance) at different initial points of flight segment and nominal longitudinal distance (decreasing nominal vertical distance) at initial points respectively, and the collision risk will decrease with increasing angle between tracks and flight gradient respectively. In conclusion, by using the model the collision risks between aircraft for different airspace planning programs can be calculated and analyzed.

Hidden Markov model for risk estimation of ship carrying liquefiable cargoes

WU Jianjun, LIU Yingxue, HU Shenping, ZHAO Yihao

2017, 27(11): 73-78. doi:10.16265/j.cnki.issn1003-3033.2017.11.013

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In order to forecast risk prospect of ship carrying liquefiable cargoes, the quantification of risk estimation in the process of ship safety operation was studied by HMM. The factors influencing ship transportation risk of liquefiable cargoes were identified, and an estimation structure model was built. The relevance of the variables was described by HMM. The model parameters were determined according to the questionnaire survey data and Baum-Welch algorithm. Voyage information was combined with forward algorithm and risk criterion to describe the risk transient and prospect. The sensitivity test of voyage risk estimation in multi-scene was carried out to verify the effectiveness of the model. The results indicate that liquefiable cargo has a big influence on the navigation risk in the pre-stage of the voyage, whose influence degree is 1.49, and the environmental deterioration has a huge impact on the risk in the post-stage, whose influence degree is as high as 1.65.

Analysis of correspondence between type of traffic accidents and types of violations

LIU Lin, FU Hui, LYU Weitao, HU Gang, WANG Chen, ZHANG Zhe

2017, 27(11): 79-84. doi:10.16265/j.cnki.issn1003-3033.2017.11.014

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Illegal driving usually results in traffic accidents. This paper was aimed at exploring the internal relation between illegal driving and traffic accident by analyzing the drivers' historical behavior. 13 types of illegal driving with relatively high frequencies and abnormal expected values were identified from 184 types of illegal driving by using normalization and threshold method. The correlations between illegal driving and traffic accidents were demonstrated by chi-square test. An influence degree model was built for correspondence between types of traffic accidents and types of illegal driving by the corresponding analysis method. The results show that there is a significant correlation between types of traffic accidents and types of illegal driving, and that for a given driver, a probable traffic accident type can be predicted from his or her driving experience.

Thermal hazard analysis for synthesis of tert-butyl peroxybenzoate

CUI Fusheng, JIANG JunCHENG, ZHANG Wenxing, NI Lei, JIANG Jiajia

2017, 27(11): 85-90. doi:10.16265/j.cnki.issn1003-3033.2017.11.015

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For the sake of minimizing the thermal hazard of two step synthesis reaction of TBPB, an RC1e was used to study the effect of reactant amount on the reaction heat (ΔH_m), adiabatic temperature rise (ΔT_ad), and MTSR of the reaction. Gas chromatography was used to detect the yield of TBPB and the conversion rate of tert-butyl hydroperoxide (TBHP). The relationships between them and ΔH_m, ΔT_ad, and MTSR were analyzed. DSC was used to study the thermal decomposition characteristics of the products of the synthesis reaction of TBPB. Moreover, the possibility and severity of thermal decomposition were estimated for the products. Results show that ΔH_m, ΔT_ad, and MTSR of the second step in the synthesis reaction are higher than those in the first step, that increasing in benzoyl chloride can enhance ΔH_m, ΔT_ad, and MTSR, that excess of benzoyl chloride can reduce the yield and increase the thermal hazard of the reaction, and that an increase in benzoyl chloride, can reduce the possibility and severity of thermal decomposition of the products in the second step.

Study on risk identification system and method for hydropower project

LONG Shuang, WANG Yongtan, KONG Fanchen, FANG Guojun, LANG Hongjun, WANG Dongmei

2017, 27(11): 91-96. doi:10.16265/j.cnki.issn1003-3033.2017.11.016

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In order to identify and analyze the risks in hydropower project comprehensively and systematically, to avoid the problems of repetition, crossing and omission, a risk identification system was constructed based on HALL three dimensional model of risk identification. Before constructing the system, the construction project was divided into several professional sections, and then the risks were identified based on the professional sector subsystems. On the basis of point, line, surface, body, operation flow was taken as the main line. Scientific identification methods such as failure mode and effect analysis (FMEA), job hazard analysis (JHA), operation conditions risk analysis (LEC), preliminary hazard analysis (PHA) were applied to equipment facilities, operating processes, personnel positions and environmental atmosphere, four specific management objects, then, a dynamic risk factor database was formed. Finally, the reconstruction project of a hydropower station was taken as an example, to which this risk identification system was applied. The results show that the system can be used to identify risk factors in hydropower project comprehensively.

Prediction of methane productivity of multiple branches horizontally-butted well and parameter optimization

DENG Cunbao, FAN Yongpeng, ZHANG Xun, LI Fengqi

2017, 27(11): 97-102. doi:10.16265/j.cnki.issn1003-3033.2017.11.017

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In order to enhance the effect of multiple branches horizontally-butted well for gas (methane) control and improve gas drainage rate, a model was built for production prediction. With the engineering background in Shaqu coal mine,the effectiveness of the model was authenticated, the distribution of gas inflow per unit length of well bore was studied, the effect of drilling morphology on its productivity was analyzed, The results show that the gas inflow into the main well of multiple branches horizontally-butted well has an u-shaped distribution, the gas inflow at the intersection is concave, the gas inflow into branch wells increases with the distance from the intersection point, that when the footage and the angle are the same, production of well bore with asymmetric structure is higher than that of the well bore with symmetric structure, that the productivity of horizontal wells increases with the increase of the angle between the main and branch well, and that when the total length of branch wells is constant, the productivity decreases with the increase of the number of multilateral wells.

Experimental study on burst tendency of water-bearing coal and its acoustic emission-charge time frequency domain signal characteristics

XIAO Xiaochun, JIN Chen, WU Di, DING Xin, YU Fei

2017, 27(11): 103-108. doi:10.16265/j.cnki.issn1003-3033.2017.11.018

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In order to predict the rock burst tendency accurately, experiments were carried out on samples of water-bearing coal from Fuxin by using a loading system and signal monitoring systems. The relationships between the rock burst tendency and AE-charge time-frequency domain signals in the failure process were studied. Three conditions, drying 24 hours, natural and the saturated, were considered. The experimental results show that, as the moisture content of coal decreases, the coal rock burst tendency stronger becomes, that change in the signals is regular in the failure process, that in time domain, with coal rock burst tendency becoming stronger, AE waveform and charge are more intensive, and the amplitudes become higher at intensification stage and post-peak stage, and that in frequency domain, a stronger rock bust tendency makes frequency of AE-charge spectrogram shift to low-frequency domain, and the amplitudes of signals in low frequency state greater.

Experimental study on deformation and acoustic emission characteristics of coal samples under cyclic loading

GUO Junjie, CHENG Xiaoyang

2017, 27(11): 109-115. doi:10.16265/j.cnki.issn1003-3033.2017.11.019

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The effect of the axial stress level on fracture evolution during the fatigue failure process of coal samples was studied using a test system consisting of a rock mechanics testing machine and a acoustic emission instrument. The results show that under cyclic loading, the deformation process of coal samples has a deceleration phase, an uniform phase and an acceleration phase, that there is a change of sparse-dense-sparse in the hysteresiscurves, that both the density of the hysteresis loop and the fatigue life are proportional to the stress level, that acoustic emission is characterized byobvious stages, that the higher the stress level is, the more intense the acoustic emission activity in each stage will be, that the fracture evolution process of coal sample is includes an initial damage stage, a stable stage of development of micro cracks and a crack failure stage, and that there is a positive correlation between both the crack initiation and propagation in a single cycle and the stress level.

Experimental study on ground settlement caused by dynamic shield tunneling

ZHU Fengbin, MIAO Linchang, LIN Shuixian

2017, 27(11): 116-120. doi:10.16265/j.cnki.issn1003-3033.2017.11.020

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For the sake of predicting the ground settlement due to dynamic shield tunneling exactly, an independently developed test device was used to simulate the dynamic construction of shield tunnel under different ground loss rates. The results show that with different ground loss rate, shield excavation face passing the monitoring cross section will cause sand ground settlement increase rapidly,no matter what the ground loss rate may be, and its growth will increase with the increasing of ground loss rate, and that when shield excavation face passes the monitoring cross section by about two times of tunnel diameter, sand ground settlement will be stabilized with advancing of shield tunneling, and the stable sand ground settlement groove width decreases with the increasing of ground loss rate.

Research on support difficulty classification for roadways with thick mudstone roof and its application

MA Zhenqian, JIANG Yaodong, WU Guiyi, ZUO Yujun, GAO Lin

2017, 27(11): 121-125. doi:10.16265/j.cnki.issn1003-3033.2017.11.021

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To classify the support difficulty of roadways with thick mudstone roof, CPM, a good mathematical method to solve complicated nonlinear problems was adopted. 12 factors, including the thickness, strength, depth etc. were selected to build CPM evaluation index system. Based on catastrophe theory and fuzzy mathematics theory, roadway support difficulty was classified into four levels, Level Ⅰ easy-supporting type, Level Ⅱ moderate-difficult-support type, Level Ⅲ relative-difficult-support type and Level Ⅳ extreme-difficult-support type. On the basis of the assessment of support difficulty levels, control measures based on bolt-net support technology were presented. This method can be used to determine regions with greater difficulty in support, which provides the basis for optimizing the support mode. The engineering application made in the Huangyanhui coal mine shows that the support difficulty classification is accurate.

Study on rapid determination of imbibition height of remolded coal by water sensitive indicator

YUE Jiwei, WANG Zhaofeng, CHEN Jinsheng, LI Haowei

2017, 27(11): 126-131. doi:10.16265/j.cnki.issn1003-3033.2017.11.022

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In order to accurately and rapidly determine the imbibition height of added water in porous media, guide hole arrangement distance of coal seam infusion and reduce the gas content in coal seam, a water sensitive indicator, consisting of titanium dioxide, calcium carbonate, titanium dioxide and so on, was developed.Using the water sensitive indicator to test imbibition heights of the remolded coals that consist of different ratio of particles and pressing loads, then compared and analyzed the imbibition height obtained by water sensitive indicator and slice method test sudden change of water content.The results show that mixing titanium dioxide, calcium carbonate, titanium dioxide, cobaltous sulfate, cobalt thiocyanate and water according to the mass proportion of 1∶2∶5∶6∶13∶32 can produce a water sensitive indicator, and that imbibition heights obtained by water sensitive indicator test agree well with those obtained by using the slice method, and the relative errors are less than 7%.

Influence of coal permeability anisotropy on in-seam borehole gas extraction

FAN Chaojun, LI Sheng, LAN Tianwei, YANG Zhenhua, LUO Mingkun, TAO Mei

2017, 27(11): 132-137. doi:10.16265/j.cnki.issn1003-3033.2017.11.023

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In order to reveal the influence of permeability anisotropy on coal seam gas extraction, an anisotropic permeability equation was derived after assuming that the coal seam is an elastic continuous medium with pore-fracture structure and a hydraulic-mechanical coupling model considering two-phase flow was built for gas extraction, on the basis of the multiple-field coupling theory. Based on the permeability in different directions of coal seam measured by experiment, both the reasonable drilling spacing and the arrangement direction of coal seam gas extraction were determined by numerical simulations. The results show that a pressure reduction zone with elliptical shape is formed near the borehole due to the permeability anisotropy, and then the pressure reduction zone becomes drum shape with the limitation of coal seam thickness, that when taking 120 days as the deadline for gas extraction, the rational space is 2.346-2.598 m under the condition of simulated working face, that the gas extraction volume increases with the rising of the angle between borehole direction and maximum permeability direction, and that for the sake of increasing the gas extraction, the direction of drilling arrangement should keep a larger angle with the maximum permeability direction of coal seam.

Study on safety of military and civil aviation in military multi-aircraft training airspace

LI Han, YAO Dengkai, ZHAO Guhao

2017, 27(11): 138-143. doi:10.16265/j.cnki.issn1003-3033.2017.11.024

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In order to avoid flight collision effectively, Event model was used to make the delimitation more scientific and credible. By simulating military craft's path, building a collision probability model and calculating frequency of side spacing loss under the influence of the navigation error, military pilot error and lateral wind, risk of collision between a military craft and a civil craft was studied. Training in "clip-on attack" was taken as an example and the safety redundancy conforming to safety target rank of International Civil Aviation Organization(ICAO) was obtained by using the collision probability model. The results show that for the given military craft and the given civil craft in the training airspace, adding safety redundancy of 8 kilometers to the nominal path width, can satisfy the requirement of ICAO safety guidelines.

Study on overburden failure models and height of water flowing fractured zone in fully mechanized caving mining

ZHAO Gaobo, GUO Wenbing, YANG Daming, LOU Gaozhong, ZHENG Dongjie

2017, 27(11): 144-149. doi:10.16265/j.cnki.issn1003-3033.2017.11.025

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The paper was aimed at working out a new method for predicting height of water flowing fractured zone in order to ensure the safety of coal mining under water body. Mechanical models were built for overhanging integrity strata, cantilevered rock failure and fracture blocks. Mechanisms were analyzed for roof breaking down at first, cantilevered rock fracture and blocks structure instability. Furthermore, the theoretic calculation method of the height of water flowing fractured zone was worked out for fully mechanized caving mining. The theoretic calculation method was used to predict the height of water flowing fractured zone for a fully mechanized caving face in the Shaping mine. A predicted height comparison was done between the method and other two methods. The result shows that the theoretical prediction height is consistent with the regression analysis and the numerical simulation height.

Analysis of multithermo-sources superimposed effect on ventilation dedusting in coal preparation plant

CHEN Xi, GE ShaoCHENG, ZHANG Xinghua, ZHANG Zhongwen, GE Fei

2017, 27(11): 150-156. doi:10.16265/j.cnki.issn1003-3033.2017.11.026

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In order to explore the influence of multithermo-sources superimposed on dust particles transient diffusion, based on the coupled thermo-hydro-mechanical model, the distribution of space temperature and the dispersion law of dust particles were studied by using Fluent software. Related experimental study was conducted in Anjialing coal preparation plant. The simulation and experimental results indicated that temperature gradient was formed quickly in the high-temperature area under the influence of thermal radiation of internal heat sources. At the same time, the thermophoresis force played a dominant role in dust particles diffusion which resulted in dust accumulation on the surfaces of equipment and ground. The dust concentration was 394 mg/m³. Through comparison of temperature from simulation results and measuring data in the postern, the modeling results have been proven to be reliable. The interrelationship and interreaction of multi-physical coupled fields, which was composed of heating dissipation, airflow field and particles dynamic field in the enclosure space, were verified by the coupled thermo-hydro-mechanical method. The research findings further revealed the dust dispersion characteristics in preparation plant and had important scientific significance in improving the efficiency of dust removal.

Research on safety manager leadership style constructs and influence on safety performance

WANG Dan, GONG Jingjing

2017, 27(11): 157-162. doi:10.16265/j.cnki.issn1003-3033.2017.11.027

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In order to improve the employees＇ safety performance, using the method of empirical research, the leader ship style's constructs and connotation of safety management in high-risk industry were identified by analyzing the 397 valid copies of questionnaire in 3 stages. The influence of leadership style on safety performance was verified by the measurement scale. The results show that the leadership style is a five-factor structure including autocratic, abusive, benevolent, transactional and laissez-faire, that the dimensions of leadership style have a significant impact on the safety performance, autocratic and abusive leadership have a positive effect on safety compliance, a negative effect on safety participation, benevolent leadership and transactional leadership have a significant positive effect on the safety compliance and the safety participation, and that laissez-faire leadership has a negative effect on the safety compliance and a positive effect on the safety participation.

Studying relationship between safety inputs and safety performance of construction by agent-based model

FENG Lingxiang, LIN Xinchao, GU Yifan, WANG Xinli

2017, 27(11): 163-168. doi:10.16265/j.cnki.issn1003-3033.2017.11.028

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Based on the statistics from the field study of construction programs in Tianjin city and Zhejiang Province, the ABM was used to explore the approach to optimization of safety input scheme. In the Netlogo software environment, it ran with the Monte Carlo method for the sensibility ranking and finding the variation tendency of safety performance. The results show that when safety inputs and especially inputs of safety precaution increase, the majority of safety performance has a significant rise with a distinct marginal diminishing effect, that inputs of safety precaution obviously have synergy effects with safety equipment inputs and safety supervisors' salaries, that accident fatalities impose upper limits on the effect of safety equipment inputs, which indicates the existence of Pelzman effect, and that in most cases, there is an optimal value in total expense can reach an optimal value as the safety inputs increase.

Study on damage alarming for a pile plate retailing wall

XU Qian, YANG Chao

2017, 27(11): 169-174. doi:10.16265/j.cnki.issn1003-3033.2017.11.029

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To prevent collapse of retaining walls, a wavelet packet frequency band energy spectrum analysis was performed for the virtual impulse response function of a retaining wall under the effects of excitation based on the wavelet packet frequency band energy spectrum theory. A damage feature vector spectrum and a damage alarming index were created. On the basis of both the spectrum and the index, a three-level damage alarming method was worked out for retailing wall structures. To verify the feasibility and effectiveness of this alarming method, vibration tests on a pile plate retaining wall were performed. Results show that damage state of the retaining wall can be alarmed via the damage feature vector spectrum, partial damage location of the wall can be alarmed via the alarming index trend surface, and damage intensity of the wall can also be alarmed via the quantitative relationship between the damage intensity and the alarming index.

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