Study On Rock Structural Analysis And Control Technique For Gob-side Entry Retaining Under Typical Roof Conditions

Gob-side entry retaining is a promising technology with the green mining and scientific mining. But because the long time activity of the roof,high stress concentration and strong dynamic pressure, the roadway deformed and damaged seriously, and maintained difficultly, which cause the applications stagnant. The existing research on the roof structure movement and stress distribution, dynamic evolution of aspects are not gone far enough. The control methods of gob-side entry retaining still cannot control the deformation and damage effectively. Therefore, the technology development and application of gob-side entry retaining is restricted.This dissertation systematically studies the roadside support resistance, the law of roof collapse and deformation characteristics and evolutional rules of surrounding rock stress by adopting the theoretical analysis, three-dimensional numerical simulation and the method of combining physical simulation experiment with industrial test. This dissertation put forward the "trinity" strengthening support technology of gob-side entry retaining, which has been successfully applied in engineering practice, made the following findings:(1) Through utilizing the continuous laminate model and considering the factors of the support effect of the coal side in the roadway, the incentives of roof caving, etc., the calculation formulas of roadside support resistance under three kinds of roof conditions are obtained.(2) According to physical simulation experiment, the law of roof caving and deformation of gob-side entry retaining under the three typical conditions are studied. The experiment result shows that with the decrease of the thickness of direct roof, the position of basic roof breaking is closing to the filling body from the goaf side. The more thickness of immediate roof decrease, the more the basic roof rotary angle and the roof caving angle increase.(3) Through applying the combining study method of three-dimensional numerical simulation, plane strain physical simulation experiment and field measurement, the surrounding rock stress dynamic development and evolution of the tunnel excavation, mining, stable process under three typical roof conditions are studied systematically. Meanwhile, the effect of roof bearing capacity of filling areas to the surrounding rock stress distribution is analyzed.(4) Based on the stage of stress distribution and failure characteristic in the gob-side entry retaining, it put forward the idea of roadway retained surrounding rock controlling of dynamic release-pressure and whole strengthen in the adjustment stage of mine-induced stress, formed the"trinity"hardening support technology system of bolting enhanced for roadway, filling body enhanced and assistant enhanced of self-moving roof-control support.The above results are applied successfully in two pilots of the Guqiao coal mine and the Wolonghu coal mine under three typical roof conditions.