Key technology and technique of large diameter rescue boreholedrilling under complicated conditions geological

In order to realize a first domestic construction drilling of a large diameter rescue borehole, the paper researched the major technique and technology of the domestic large diameter drilling borehole and the overseas large diameter rescue borehole. According to the extremely complicated pore forming conditions， such as the continuous collapse leading to bury drill,trough the karst cave aquifer and trough the prone stratum in the goaf of Pingyi Gypsum Mining Area, the ø711 mm large diameter DTH hammer drilling technology, the air reverse circulation process, the borehole deviation prevention and vertical control and other technique and technology were studied and implemented. Meanwhile, accordantly the solutions were provided to the surface ground subsidence and working pipeline deformation and others. The practices showed that the successful construction of the large diameter rescue borehole could provide the experience references to realize the rescue with the domestic large diameter boreholes.