Transportation patterns of drilling cuttings and application using the internal row drilling cuttings method in rockburst mines

This study proposes an internal discharge drilling cuttings method and corresponding drilling tools as a solution to inaccurate collection of drilling cuttings in existing drilling cuttings methods. Its mechanism is to transport drilling cuttings out of the hole tiorough the internal channel of the drilling tool by negative pressure. The drilling cuttings were collected and weighed. Their transportation patterns under negative pressure were analyzed via theoretical analysis.The CFD-DEM coupled numerical simulation was conducted to study how different structures of transportation channels influence the drilling cutting-gas flow. The drilling rod was processed based on the numerical simulation results. Laboratory experiments were conducted to verify the feasibility of drilling cuttings collection by the internal discharge drilling cuttings method. Results indicate that 1) Higher pressure differences lead to faster transportation of drilling cuttings; 2) Under the same negative pressure and drilling speed, the cross-sectional size of the fluid hole at the end of the drilling tool is directly proportional to the efficiency of drilling cuttings transportation under negative pressure; 3) Increasing the number of fluid holes could promote the efficiency of drilling cuttings transportation under negative pressure; 4) When the fluid hole is tilted 30 degrees towards the drill bit, it exhibits the optimal transportation performance of drill cuttings under negative pressure.