|
Abstract Experiments are carried out to study the hard sandstone under uniaxial compression and different confining pressures with triaxial compression by the rock mechanics testing machine RMT–150B in deep coal mine，and basic mechanical properties of sandstone are measured. According to the rock stress-strain curves，strength properties and deformation characteristics of deep-seated rock are analyzed. The results show that rock compression strength increases by 40.3% with confining pressure from 10 to 15 MPa. The deformation and failure pattern of sandstone are closely related to confining pressure. The slope of main stress difference-strain curves are steep significantly with the increasing of the confining pressure. Based on the mechanical properties of rock，the 42 mm in diameter drill bit is adopted for the cutting holes and the 32 mm in diameter drill bit is used for the surrounding holes in order to save the drilling time. The different steps of millisecond inclined cutting with medium-length hole are proposed，and the depths of 2.2–2.5 m for blasting hole are reasonable which are beneficial to the footage. The surrounding hole with small diameter is beneficial to the roadway forming.
|
|
Received: 27 July 2009
|
|
|
|
