1958 年 74 巻 839 号 p. 283-286
This investigation was carried out for the purpose of obtaining materials for the layout of pillar working or of driving close parallel headings. The stress state in an elastic ground with six parallel openings, square in section, was analysed by means of photo-elastic experiments under the initial stress in one direction as well as in two directions. The results are as shown in Fig. 3 and 4. The conclusion to this research will be given in the 2nd report.