Deformation and control countermeasure of surrounding rocks for water-dripping roadway below a contiguous seam goaf

Abstract

To solve the technical problem of supporting a water-dripping roadway below contiguous seams at the Tuanbai coal mine, the deformation law of surrounding rocks for the roadway was studied using Fast Lagrangian Analysis of Continua in Three Dimensions (FLAC3D) numerical simulation. Then, a mechanical model of water-dripping rock using a bolt support was established, and further, technical countermeasures to control the deformation of the roadway with a bolt and cable support are proposed. The results show that the erosion of the water dripping on the roadway was substantial and showed notable changes over time during roadway excavation and mining work. These effects caused the road to heave slightly, but it tended to be stable during roadway excavation. Moreover, the erosion of the roof and two ribs increased exponentially, and the floor heave increased with significant displacement oscillation during mining. The anchoring length of bolts and the rock weakening from water dripping had noticeable effects on the surrounding rocks of the roadway. The logical parameters of the bolt spacing and tightening force (the bolt line spacing was 0.7-0.9 m and the tightening force exceeded 40 kN) of the bolt supports were studied and optimized. Finally, a support scheme for water dripping on the roadway at the Tuanbai coal mine is proposed. The observation data regarding the deformation of the surrounding rocks, monitoring of bolt and cable stress, endoscopy results of roof failure, and roof bed separation monitoring were used to verify the reasonableness of the scheme and ensure the requirements for support were met. The study results can serve as a reference regarding the support for water dripping on a roadway under similar conditions.