Comparison and Application of Two types of Filling Gel to Prevent Spontaneous Combustion at the Region where Top-Coal Caves above EntryYuhuai Wang, Hang Suo, Yao Shan, Bo Yu, Erxiao Liu and Fei HouMATEC Web Conf., 67 (2016) 07015DOI: https://doi.org/10.1051/matecconf/20166707015