# Cause Analysis of Coal Mine Gas Accidents in China Based on Association Rules
## 2 Methods
### Data Analysis Method
#### 2.3.2. Association Rule Method
After the frequent item set is obtained, the Apriori algorithm is used to mine association rules. According to the comparison of experience and results, the confidence degree is set as 0.4. One factor in the frequent item set is taken as the front term of association rules, and the other factors are taken as the back term, respectively. Accident Cause Chains Method  
The occurrence of coal mine gas accidents is the result of the interaction and joint action of various factors. According to association rules, a more intuitive cause chain of coal mine gas accidents is constructed, from which three cause chains are extracted for analysis and countermeasures and suggestions are put forward. Results and Discussion  
The Accident Statistics  
Factor Frequency Statistics  
First of all, the analysis of the occurrence frequency of these accident factors can provide a better basis for the production of association rules. The frequency of occurrence of factor keywords is analyzed and the proportion of these factors in accidents is analyzed. The factor names in Figures 3 and 4 correspond to the label in Figure 2.  
The results of statistical analysis for human and equipment factors are as follows:  
It can be seen from Figure 3a that \"Habitual violations\" occurred 121 times in total, accounting for 32.3%, which is also the factor with the most frequency among the four aspects of the factors, followed by \"Missing procedures steps\" in skills errors, which occurred 70 times, accounting for 18.7%. \"Poor personnel safety awareness\" appeared 43 times, which shows that the safety education and training of personnel in most coal mining enterprises, as well as the establishment of personnel safety awareness, are not in place. In Figure 3b, the factors of \"equipment missing/imperfect\" is mainly reflected in the safety monitoring system and ventilation system, 43 times and 38 times respectively, accounting for 30.7% and 27.1% of the machine factors; security monitoring. For example, gas accumulation in the roadway is caused by unreasonable ventilation design or failure to open local ventilators, and abnormal concentration of gas is not detected by safety monitoring equipment, so coal mine gas accidents easily occur [27; 28]. \"Explosion-proof measures not set\" and \"Gas extraction system missing/imperfect\" only accounted for 5.7% of the total equipment factors, which therefor had little reference significance. In addition, \"Normal equipment but not running\" and \"Equipment failure\" occurred 20 times and 31 times, respectively, accounting for 14.3% and 22.1% of the total equipment factors, indicating that compared with equipment missing/imperfect, the factor of \"equipment failure\" is relatively rare. Figure 3: Frequency statistics of personnel and machine factors. The results of statistical analysis for environment and management factors are as follows:  
Figure 4a shows that in terms of environment, which is the main cause of accidents, gas accumulation accounted for 45.5% of the environmental cause factors, followed by coal seems with outburst danger which accounted for 31.8%. In the process of sorting out the  
Figure 4: Frequency statistics of environmental and management factors. accident causes of the accident report, it is also found that most of the coal mines where coal and gas outburst accidents occurred are identified as having outstanding risks. The occurrence of \"Strong spontaneous combustion tendency\", \"Abnormal gas emission\", and \"Soft coal seam\" is less common. It can be seen from Figure 4b that among all factors, management factors appear the most frequently, indicating that management factors are more important in ensuring coal mine production safety.