Study on failure mechanism and comprehensive strengthening technology of roadways and chambers group at shaft bottom

In order to solve the problem of repairing roadways and chambers group at sub-shaft bottom in Zhangcun Coal Mine, this paper reveals the cause of deformation and failure of roadways and chambers group through geological sketch and field test. The numerical simulation method is used to study the large-scale chain failure mechanism of roadways and chambers group.Based on the theory of intensive support and reinforcement control of surrounding rock, the comprehensive reinforcement technology of deep and shallow hole double liquid grouting combined with full-length anchoring cable was developed. The results show that:① Unfavourable geological structure and stress environment,unreasonable downhole stratum,insufficient structural design strength and multiple blasting disturbance are the main causes of deformation and destruction of surrounding rock of roadway chamber in Zhangcun Coal Mine.② Under the high concentrated stress and frequent disturbance caused by intensive excavation, the damage scope of roadways and chambers group is much larger than that of single roadway excavation. The interaction between chambers aggravates the degree of destruction, which is the mechanism of deformation and destruction of the chamber of the roadway in Zhangcun Coal Mine.③ Grouting is carried out by means of deep-hole shallow holes crossing each other and inorganic-organic pulp complement each other, double-guarantee grouting effect, fully filling surrounding rock fissures, and full-section strong anchor bolt support.It is equivalent to adding strong boundary conditions to the periphery of the tunnel chamber, so that it has strong resistance to deformation.Grouting is carried out by means of cross-cutting deep and shallow holes and complementary inorganic-organic grouting materials, thus ensuring the grouting effect and fully filling the surrounding rock fissures, while full-section strong bolt and cable support is equivalent to adding strong boundary strips around the roadway chamber. The research findings have certain theoretical guidance and practical reference significance for the reinforcement engineering of underground permanent roadway chamber under similar geological conditions.