Abstract At present, non-pillar entry protection in longwall mining is mainly achieved through either the gob-side retaining (GER) procedure or driving (GED) procedure. The GER leads to difficulties maintaining roadway both previous and current panels. A narrow coal pillar about 5–7 m must be left GED procedure; therefore, it causes permanent loss of some coal. pre-backfill (GPD) effectively re...

The purpose of this paper is to report the first stage of the implementation within FLAC of a hydromechanical model using an iterative procedure between two independent hydraulic and mechanical sub-models. The fracture network of the rock mass is considered using the multilaminated medium concept. The implemented model is illustrated through its application to the hydraulic circuit of the Venda...

Based on STL (stereo lithography) format file and with Microsoft Visual C++ 6.0 programming language, a 3D printing slicing software appropriate for the surface strengthening of parts has been developed, which includes three functions: model import, data export. Through grouping triangle facets before slicing, judgment times relationship between cutting planes are reduced, efficiency is improve...

Directional long drilling on the roof is an effective gas control measure in goaf, but there little research stability of surrounding rock. In this study, geological conditions #4 coal seam Tingnan Coal Mine, Shaanxi Province, China taken as application background, and deformation characteristics boreholes under four typical rock were first analyzed based Universal Distinct Element Code (UDEC) ...