Calculating stresses in support and sidewall rocks in stagewise face drivage in long excavations

The issues of calculation of stresses and strains in the elements of support and in rock mass in stagewise drivage of a production face are under discussion. In order to take into account the sequence of mining and support installation, it is required to solve problems on extra stresses due to small cross-section drivage. Geomechanical estimation of support and rocks used the method based on single formation of stiffness matrix to describe rock mass prior to mining start. Sequential drivage of excavations and change of mechanical properties in the calculation system are modeled using initial stress procedure. The author calculates two scenarios of mining with stagewise face drivage under conditions of elastic deformation of rocks and support and analyzes behavior of stress redistribution in elements of support being installed in stages. It is shown that mining sequence considerably influences stresses in the support elements upon the drivage completion. The scenario of mining with initial installation of sideways support elements results in increased tensile stresses in the support as against the scenario when the underroof space is first mined out and supported.