Distribution characteristic of mining-induced horizontal fracture in longwall panel: Field investigation and prediction model

Abstract

Mining-induced overlying strata fractures have always been the research focus in mining and civil engineering. In this study, the distribution characteristic of mining-induced horizontal fracture was systematically investigated by means of field verification and theoretical analyses in four study area. The following results were obtained: Horizontal fractures mainly occur at rock layer interface with larger aperture caused by uneven settlement between adjacent strata. In addition, a few horizontal fractures can occur in rock layer's interior with tiny aperture. The two-layer structure (i.e., upper- strong and lower- weak rock layer) do not necessarily lead to horizontal fractures along layer interfaces under the effect of coal mining. The improved key stratum theory prediction model (IKS) has significant advantage for predicting the location of horizontal fractures along rock layer interface compared with other models (i.e., Palchik's method, key stratum theory, and maximum curvature method).