A method for determining the overburden failure height of coal mining based on the change of drilling speed and the leakage of sectional water injection in underground upward bolehole

Abstract

A coal mine in Xinjiang was taken as research site in this paper, it is proposed to determine the overburden failure height based on both the drilling speed of upward bolehole and sectional water injection methods. The results show that the overburden failure height of borehole CH01 is 44.80m based on the drilling speed and 44.32m based on the sectional water injection method respectively, with the difference 0.48m; also the results of borehole CH02 is 42.58m and 40.59m respectively, with the difference 1.99m.The overburden failure height determined based on the drilling speed is basically the same as the results aquired by the sectional water injection method. The latter validates the former's accuracy. So the overburden failure height of mining based on the drilling speed in underground upward borehole has good accuracy, also the height of caving zone can be aquired by this method. Both of the methods verified each other, and provides a new way for field measurement of overburden failure height in coal mines.