Study on statistics and classification of uniaxial compressive strength of coal

In order to solve the problem of low utilization rate of the existing uniaxial compressive strength（UCS） test data,the methods of data screening and analysis,mathematical statistics,and cluster analysis are used to distinguish and measure the difference of coal strength effectively,and to quantitatively evaluate and classify the UCS test results.By collecting and sorting 808 sets of coal UCS data from 129 coal mines in major coal-producing provinces such as Shanxi,Shandong,Inner Mongolia,Shaanxi,Xinjiang,etc,the distribution characteristics and law of coal UCS data were analyzed and the test results were evaluated,which provides an important reference for coal body strength classification and related engineering design of coal measure strata.Based on the statistical analysis of the coal strength test data,the coal strength is classified and the coal strength classification and evaluation results are used to provide a reference and predictive evaluation of the support parameters of the coal mine roadway surrounding rock.The results show that the UCS distribution range of the coal body in this paper is 1.37～55.48 MPa,with an average value of 16.11 MPa and a standard deviation of 8.93 MPa,which satisfies the normal distribution.In addition,the UCS of coal classification is determined:Ⅰ（1～10 MPa）,Ⅱ（10～15 MPa）,Ⅲ（15 to 25 MPa）,Ⅳ（25～40 MPa）,Ⅴ（40～60 MPa）.According to the uniaxial compressive strength grading standards,the scores are evaluated: very poor （0～10 points）,relatively poor （11～20 points）,poor （21～40 points）,moderate （41～60 points）,relatively good （61～80 points）,good JP3（81～95 points）,and very good （96～100 points）.The uniaxial compressive strength of the coal mine is scored and evaluated,and different support parameters are classified and divided accordingly.The support parameters can provide a reference for the basic parameters of coal roadway support.