Abstract
The three-level shaft of the mixed pit shaft of Yixin Mine, built in 1983, failed continuously due to the influence of geological structure and the effect of water, which formed a collapsed space with a length of 18m,a depth of 12m,and a height of 12m at the level of -255m and to the southwest end. The 54m pit shaft below the -258m elevation of the pit shaft was filled with collapsed rocks forming a large loose body. The comprehensive processing plan for falling grouting and anchoring was proposed according to the geological conditions of the vertical shaft of the mixed pit shaft, adopting three-dimensional numerical simulation software as well as calculating the mechanical state of the vertical pit shaft surrounding rocks and using 3 to 5 parameters of Williams-Warnke failure criterion.