Theoretical analysis of drilling cuttings considering stress zoning of surrounding rock and its application in stress detection

Drilling cuttings method is a commonly used method to detect the risk of rockburst, which has been widely recognized and applied in coal mines. However, in the current theoretical research on the relationship between drilling cuttings method and coal stress, it is generally considered that the mechanical parameters of coal at different positions of roadway are unchanged, and the influence of surrounding rock plastic zone and elastic zone is not considered. Therefore, according to the secondary distribution characteristics of roadway side stress, the theoretical calculation formula of drilling cuttings in the plastic zone and elastic zone of the roadway side is established in this paper. The example shows that the distribution of cuttings on the roadway side is obviously consistent with the abutment pressure. The cuttings in the plastic zone and the elastic zone are in linear and power function with the coal stress, respectively, and the cuttings in the plastic zone are greater than those in the elastic zone. With the increase of the hole diameter, the slope of the relationship curve between the drill-cutting weight and stress gradually increases, and the response of the drill-cutting weight with a large hole diameter to the change of coal stress is more obvious. The numerical simulation results show that the error of the theoretical calculation formula of the drilling cuttings method is less than 9%, which can meet the engineering application needs of estimating the drill-cutting weight in coal and the stress of coal. Using the theoretical formula, the stress field in the leading area of the working face is measured, and the leading influence range and the accurate position of the high stress concentration area are determined, which provides more comprehensive stress information for the early warning of impact danger and pressure relief.