在四矿井田F_3与F_6断层所圈定的范围(见图1)内,于1973年3月13日,在井下-24水平施工的大_6孔,刚见大灰岩时,水量微小,当钻入灰岩0.2米时,钻具自动掉落0.1米,钻孔水量大增,水头压力约15.5公斤/厘米~2,使钻具顶住钻窝顶板无法提钻,直至6月30日才提钻, Within the range defined by the F_3 and F_6 faults in the Fourth Mine Field (see Figure 1), on March 13, 1973, a large-6 hole was constructed downhole at a level of -24. Just after the large limestone was found, the amount of water was small. Drilling into the limestone 0.2 meters, the drill automatically drop 0.1 meters, drilling water surge, the head pressure of about 15.5 kg / cm ~ 2, the drill against roof drilling rig roof can not mention drilling until June 30 before Drilling,