NUMERICAL STRUCTURAL PARAMETRIC ANALYSIS OF LONG-TERM STABILITY OF ANCIENT BELL-SHAPE CAVERNS

According to the long-term mining experience, the ancient quarrymen quarry rocks to form the bell-shape caverns without any pillar. Because the north-south and southwest-northeast gradients are different, the caverns have different cross-sections. So the bottom of caverns is approximately oval. This paper explores the scientific rules of structural features of the bell-shape caverns of Huaxuan caverns and Huaju caverns in Changyu, Wenlin, Zhejiang province, and the scientific rules of structural features. It examines the characteristics of the structure parameters of bell-shape caverns for further analysis of the influence factors of the large cavern group. The topographic slope, the span-high radio and the buried depth and height ratio of cavern are analyzed with the FLAC for analyzing the structure parameter character of the bell-shape caverns. Analysis of the stress and plastic zone shows the following results. For the gentle slope surface, the span-high radio is less than 1.44 and the height ratio is less than 1.8. For the steep slope surfacedirection, the span-high radio is less than 1.28 and the height ratio is less than 1.8. About 67.7% of the 24 caverns can meet these rules. So, the reasonable structure character of the bell-shape cavern has resulted them to have been stability for one thousand years.