Strength Calculations of Block Elements of Room-and-Pillar Mining under the Permafrost Conditions

The paper covers results of rheological properties of gypsum under natural conditions of permafrost and stress-and-strain conditions of room’s roof rocks in gypsum quarries depending upon the ceiling thickness. The recommendations concerning room and pillar parameters are given

Substantiation of chamber parameters under combined open-cast and underground mining of graphite ore deposits

The move from open-cast to combined mining method of developing Zavalyevsky deposit of graphite is considered in the paper. The selection of chamber dimension satisfying conditions of long-term stability is one of the questions for scientific substantiation of the move to combined mining method of deposit development. With this purpose physical and mechanical properties of graphite and enclosing rocks are determined. Stress and strain condition of rocks around the chambers using the method of finite elements is studied

Analysis of and Strain Condition of Rock Massif Around the Special Purpose Rooms Using Numerical Method

ABSTRACT: the investigation concerning selection and substantiation of special purpose room dimension designed for locating underground dressing mills in condition of magnetite quartzite deposits. Special purpose rooms are the rooms of great dimension designed for locating underground dressing mills, large underground grinders, plants, oil storage tanks, etc. As stopping chambers and special purpose rooms have three dimensions and numerically slightly differ from each other under ore mining, stress condition of rock massif was studied in extensional position. While studying stress and strain condition of rocks around the workings, potential and finite-element methods were used taking into account the versatility and simplicity of their solution. Boundaries of influencing edge room on stresses in mid plane surface of the rooms were determined. Conclusions are made about the fact that if the length of the working is three panels, the further increase of the length doesn’t influence on stress and strain condition of mid plane surface. Solution in condition of plane problem and solution in extensional position were compared Stresses while solving extensional and plane problems are similar as removing from the working. Replacing extensional condition by the plane one for rooms of limited length gives the error of about 20%. The choice of room configuration of underground dressing mill meeting condition of long-term strength was made. Parallelepiped and cylindrical rooms were studied. The analysis of given results showed that the way of stresses distribution for selected room configuration is similar and numerical values of stress component have 10% difference in some points. The strength of stopping chambers within sloping bed in extensional position was determined. The results of solution were compared with solution for horizontal seam with the rooms in the same conditions. It was stated that stresses in the centre of room panels of horizontal and sloping beds are slightly different. Recommendations concerning selection of room configuration for locating there underground dressing mill in condition of magnetite quartzite deposits are given