| Both in China and the United States(US), gas explosion coal mine accidents account for a considerable proportion, causing a large number of casualties and huge economic losses. Although the total number of accidents has been significantly reduced in our country in the last few years, the number of fatalities are still large compared to the United States and the major and considerable gas explosion accidents still happen frequently in China. In the US, the gas explosion accidents have been controlled effectively after 1969 when the ‘Federal Health and Safety Act 1969(Act) of coal mine is released and Behavior safety management applied to coal mines. Therefore, analyzing the unsafe action reasons in our country’s gas explosion accidents and comparing with those in the US, can provide useful information for preventing gas explosion accidents in China.77 gas explosion accidents between 2005 and 2009 in China and 46 accidents since 1950 in the US are selected and the unsafe acts are analyzed on the basis of the behavior-based accident causation “2-4” model. First, the general regularity of the gas explosion accidents, that is, the accident time, work place, and ignition source, is analyzed. Second, the unsafe acts in 77 China gas explosion accidents and 46 US gas explosion accidents are analyzed, respectively. Finally, the occurrence rules of unsafe acts and violation in the gas explosion in both China and US are compared, based on which corrections are proposed.Theory analysis, case analysis and comparative analysis on unsafe acts are conducted. First, feasibility and advantage of behavior-based accident causation “2-4” model is theoretically analyzed. Secondly, based on the case analysis, the unsafe acts in the past accidents are identified and classified into two classes: with and without violation of regulations. The acts that violate the rules are considerate as unsafe actions, while for those do not violate the rules, whether or not they are unsafe actions are determined by cross reference and experience. At last, by comparing the unsafe actions and violation in the gas explosion accidents between China and US, we can conclude that:(1)The commonalities and differences of the general regularity of gas explosion accidents between China and the US are compared. Comparative results indicate that in both China and in the US, the peak period for accidents occurred before and after the respective country’s holidays. Within a coal mine, the most frequent locations where gas explosion accidents occur are: the coal face, the heading face and the haulage roadway. In China, the gob area is another frequent accident location. Among 15 possible causes for ignition sources resulting in gas explosions, China and the US share 10, and ‘Blasting’ is the top cause of gas explosion in both countries. In China, the five major causes of gas explosion not present in the US are ‘Use of coal electric drill with loss of explosion protection’, ‘Dismantling the caplamp’, ‘Using non-explosion proof electric equipment’, ‘Spontaneous combustion’ and ‘Open fire in the gob area’.(2)Based on the analysis, there are 376 unsafe acts in the 77 gas explosion accidents in China. Among of them, there are 286 unsafe acts relevant with ignition sources that can be classified as 25 categories, and 108 unsafe act associated with gas accumulation can be classified as 27 categories. Furthermore, the most frequent unsafe act related with ignition sources is ‘illegal blasting’ and followed by ‘illegal mining’、 ‘gas detection’、‘personnel evacuation’ and ‘use of the coal electric drill with loss of explosion protection’. And the first five places in the unsafe acts relevant to gas accumulation are ‘not installed ventilation device’、‘recirculating air of auxiliary fan’、‘limited ventilation’ 、 ‘removing ventilation controls’ and ‘unqualified ventilation device’.(3)In the 46 gas explosion accidents in the US, 102 of 162 unsafe acts relevant with ignition sources are classified as 20 categories, and the rest 60 unsafe acts associated with gas accumulation are classified as 18 classes. Among of them, the most frequent unsafe act related with ignition sources is ‘illegal blasting’ and followed by ‘gas detection’、‘operating mechanical equipment’、‘ not taking dust control measures’ and ‘smoking’. And the top five unsafe acts relevant to gas accumulation are ‘removing ventilation controls’ 、‘ illegal construction’、‘unqualified ventilation device’、‘not use of bleeder system in worked-out areas’ 、and ‘not installed ventilation device’.(4) The similarities and differences in unsafe acts of gas explosion accidents between China and the US are analyzed. There are 25 kinds of unsafe acts associated with igniton source in China and 20 kinds in the United States. Among of them, there are 16 unsafe acts in these two countries are the same. There are four kinds of unsafe acts only happened in US, and nine kinds of unsafe acts only happened in China. Moreover, in both two countries, ‘illegal shooting’ is the most frequency unsafe act. And the top five kinds of unsafe acts in the two countries accounts for more than 50% of accidents. For the gas accumulation related unsafe acts, there are 27 kinds in China and 18 in the United States. Although 16 unsafe acts are the same in both countries, the frequency of these unsafe acts is different in two countries. There are two kinds of unsafe acts only occurred in the United States, while 11 kinds only happened in China.(5)The commonalities and differences of regulations of unsafe acts caused gas explosion are summarized. Among the ignition related unsafe acts, 6 kinds are similar in regulations, while the rest are different. For the gas accumulation related unsafe acts, only 6 kinds are similar too. By comparing these regulations, we find some regulations are specified in the US while not in China. For example, the diameter of a water stemming bag, weight of explosives, multiple-shot blasting, safety distance of blasting, safe distance of explosive, the horizontal distance between the bolts, removing the ignition source before the arear sealed, what need to be checked before and in the shifts, the dosage of rock dust, escape route map posted requirements, the distance, links methods and use limitation of temporary cable connection, the distance of cutout switches of trolley wires, position and distance of self-rescuer, building materials and strengths of seal, distance from line brattice to the work face, maximum distance between two air doors.(6)On the basis of our analysis, some measures for the modification of unsafe acts have been suggested in order to reduce the unsafe acts. First, to reduce the ignition related unsafe acts, much more attention to "illegal shooting", "illegal mining" and "gas detection" is necessary because the occurrence frequency of these three types of unsafe acts accounted for 62% of the total frequency of unsafe acts. To reduce the occurrence of gas accumulation, unsafe acts such as "not installed ventilation devices" and " recirculating air of auxiliary fan" need to be effectively controlled. The frequency of these two types of unsafe acts is higher than all other unsafe acts related to gas accumulation. In addition, the modification of unsafe acts associated with ventilation devices installation and use and maintenance should be strengthened too. The frequency of unsafe acts related to ventilation devices accounts for 65.74% of the total, in China and 55% in the United States. Furthermore, regulations of unsafe acts in China need to be specified otherwise lacking of operability. |
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