MONITORING ANALYSIS OF SECONDARY LINING STRUCTURE OF CENTRAL PUMP HOUSE IN DEEP COAL MINE

Based on the notion of the new Austrian tunneling method,the field monitoring of secondary lining structure of central pump house in Zhuji Coal Mine is conducted by displacement convergence gauge and steel-string sensors.And the time-dependent variation laws of surface displacement,contact stress between primary support and secondary lining,reinforcement stress and concrete strain are obtained.The monitoring results show as follows:(1) The surface displacement rate is larger at the early stage and the displacement is convergent after about 100 days of secondary lining construction.(2) The contact between primary support and secondary lining is close,which indicates that the secondary lining bears the load of surrounding rock effectively.(3) The reinforcement stress changes enormously at initial several days,then increases and achieves a steady state eventually.(4) The concrete strain is stable after experiencing a transformation from initial compressive strain to tension strain.By analyzing the monitoring data,the conclusions can be drawn as follows:(1) The final values of all monitoring items are within safety limit,which demonstrates the reliability and security of secondary lining structure.(2) The steel string sensors are easily affected by the hydration heat generated in the process of concrete hardening.(3) The mechanical state of secondary lining is disturbed by excavation of adjecent caverns.