Study On The Fracture Laws And Controlling Of Thick And Hard Roof

This paper, Based on the behavior law of mine pressure and hard roof control ,with multi-research methods, such as the theoretical analysis, the computer numerical simulation , the simulation of similar materials and field research. mainly to research the rupture regularity of thick and hard roof in fully-mechanized face, characteristics of surrounding rocks, supporter and surrounding rocks, reasonable support pattern, reasonable method and parameters of overhead caving in working face of thick and hard roof.The main study of this paper includes several accepts blow:1. When it was the primary main roof pressure, the bending moment was biggest in the two end of the rock beam. Here the tensile stress was biggest, and it's more than the tensile strength of the rock, the thick and hard roof was broken at the two end of the roof. When it was periodic roof pressure, the bending moment of the cantilever beam was at the end of clamped support, here the tensile stress was biggest, and the thick and hard roof was broken.2. As mining, the soft strata over the thick and hard strata were changed as the rupture of the thick and hard roof. The thick and hard roof and overlying strata were coordinated subsidence. The thick and hard roof plays a key role in controlling the displacement and deformation of overhead strata. So controlling the caving interval is the key to controlling roof weighting in working face of thick and hard roof.3. Different support methods have different effect to the pressure of work face, Enlarging the last pillars' pressure, the biggest tensile stress point of rock roof near the edge in the worked-out section of the last pillars, to make rigid roof more Gloss to the last pillars caving; Enlarging the maximal tensile stress to make rigid direct roof easily broken and reduce the requirement of support strength in working face.4. By the method of preceding loosening blasting in deep hole, it changed the mechanical structure of the thick and hard roof beam, it efficiently decreased the caving interval in the working face of the thick and hard roof, it weakened the ground pressure strength of the thick and hard roof, it decreased the size of rock broken, and it eliminated the phenomenon of dynamic impact when the ruptured of thick and hard roof. By this method, it ensured the coal mining safety in productionIn a word, the results in this paper plays a vital role in controlling of thick and hard roof and safe mining in fully-mechanized coal face.