Control principles for roadway roof stabilization in different zones during ascending mining

Abstract：Field measurements, physical simulations, and numerical modeling were used to de- termine the stress and fracture fields in overlying strata during ascending mining. The stability of the surrounding rock was studied and the lateral pressure coefficient, sectional shape, and rock strength were analyzed. Stress distribution and fracture evolution were determined as a function of time. The stability of rock surrounding a coal mine roadway is discussed. The roof strata are divided into regions; five damage zones in the overburden and four fractured regionsl The concepts of ＂equivalent excavation＂ and ＂inefficient reinforcement zone＂ are proposed. The lateral pressure coefficient and the orientation of the principal stress suggest a circle or an el- lipse would be a reasonable cross section for the roadway roof. Hence, increasing the depth of the floor by four to six meters is an effective action. Control principles for roof stability during ascending mining are proposed. Zones II and III are chosen for layout of the roadway. A period of 165 days after mining should be allowed before excavation. The cross section should be optimized and the inefficient reinforcement zone and stability of the support structure should should be decreased. Surrounding rock strength also be improved. These actions will successfully guide engineering practice toward control of zone strength.