In-Situ Fracturing Induced Caving of a Hard Orebody and Its Application

In-situ fracturing induced caving is proposed as a solution to the problem that it is difficult to form the cutting slot required by conventional mining to achieve sublevel caving stoping in a broken orebody affected by high-stress fracturing. This method involves the creation of a limited blasting compensation space through the construction of roadways, and then the formation of an in situ fractured area with the use of fan-shaped beam hole enhanced blasting technology, thus improving ore cavability. When the undercut area at the bottom satisfies the conditions of continuous caving, induced caving mining of a high-stress hard orebody can be achieved. This method adopts super-extrusion blasting technology in a limited blasting compensation space to fragment the ore through the combination of stress and blasting, changing the characteristic parameters of endogenic joints and fissures, and utilizes fan-shaped beam hole enhanced blasting technology to guide the design of the blasting parameters. The method also establishes a multichannel ground pressure monitoring system based on acoustic emission technology to monitor changes in ground pressure in real time during in situ fracturing induced caving mining and to guarantee mine safety. The corresponding key technologies have been applied successfully for caving mining area II of orebody no. 92 in Tongkeng mine, which provides useful theoretical and technical references for efficient blasting and mass mining at other locations where there is limited space.