The article investigates how injecting grout can help control mine subsidence by studying how the ground reacts to underground mining. The researchers installed instruments in a coal mine in Australia to measure movements and stress in the ground. They found that as the mining advanced, the ground above it started to separate and form gaps. Stresses in the ground increased significantly before the mining reached certain areas, peaking about 200 meters behind the mining face. Computer models showed that the angle of breakage behind the mining face was around 22-25 degrees from vertical, matching the high stresses observed on the surface.