Fig. 1

Mine basic conditions: (a) location of the mine, (b) columnar diagram of borehole 31 − 2, and (c) engineering map of the 301 working face. This map is based on the standard map No.GS(2022)4316 downloaded from the standard map service website of National Administration of Surveying, Mapping and Geoinformation of China (http://bzdt.ch.mnr.gov.cn/) with no modification to the base map.