Research on the fracture mechanics model of deep hole pre-splitting for forced caving

The pre-splitting for forced caving is an important technology to ensure the safe production of coal mines. In response to determine the reasonable parameters of deep hole pre-splitting for forced caving during the initial mining period, based on the characteristics of rock strata of main roof and the theory of fracture mechanics, the mechanics model of forced roof caving of deep hole pre-splitting was presented, and the sensitivity of model parameters was analyzed. The expression of the initial weighting distance of the main roof and support working resistance was deduced. The results show that the initial weighting distance of the main roof decreases with the increase of inclination or vertical depth ratio of pre-crack, increase with increase of support working resistance. The inclination of pre-crack increased from 10°to 90°, the maximum damped initial weighting distance is 83.16%. The vertical depth ratio of pre-crack increased from 0.1 to 0.9, the maximum damped initial weighting distance is 65.84%. The support working resistance increased from 3MN to 18MN, the maximum amplified initial weighting distance is 1.4 times. The theoretical calculation is compared with the actual field measurement, which indicated the reliability of the model. The research results can provide guidance for the design and construction of deep hole pre-splitting, have important theoretical significance and engineering value.