A study of angle of draw in mining subsidence using numerical modeling techniques

Mining subsidence is a well recognized problem in many countries. Particularly in the recent years with increasing demand for energy and resources, mining activities have been extended to a limit where previously being regarded as no-mining zones. It is important to understand the mechanism involved in the substratum movement induced by underground mining. One of the key parameters in subsidence analysis and prediction has been the angle of draw which defines the limit of the subsidence affecting the surface. Most of the traditional empirical subsidence models are reliant on the value of angle of draw. In this paper numerical modeling techniques were used to study the mechanism of substratum movements and the associated subsidence limit at ground surface. Particular emphasis is placed on the effects of overburden stiffness and the extraction seam dip angle on the values of angle of draw. The analytical results are discussed in the context of observational data worldwide.