Research On Synergistic Support Of Rock Bolt In Deep Coal Mine Roadway

The problem of coal mine safety support has become the primary problem that restricts the development of coal mines.Although the bolt support theory and technology are widely used in roadway support,the anchoring mechanism between bolts and anchors and between anchors and surrounding rocks is lack of effective understanding.Aiming at the scientific problem of bolt support in surrounding rock of deep coal mine roadway,this paper takes the bolt system composed of surrounding rock and bolt as the research object,mainly combines physical model test with numerical simulation method,analyses the variation law and synergistic effect of the internal stress field of anchor under different factors such as pre-tightening force,length,density,drilling angle of bolt and confining pressure.The strength characteristics and deformation characteristics of the anchor under the synergistic effect are studied.Based on the synergetic theory and through on-site monitoring,the effect of roadway anchor should be evaluated and analyzed,and the mechanism of synergistic bolt support in surrounding rock of deep coal mine roadway should be revealed.The results of the dissertation are presented as follow:?1?Based on the theory of synergy,an evolution equation is established to reflect the displacement variation of the surrounding rock stability of the roadway.The order parameter equation can better represent the feedback,coupling mechanism and subsystems in the surrounding rock stability system of the roadway.The nonlinear relationship between the co-evolution and the adiabatic elimination method is used to obtain the stationary and non-stationary solutions.?2?The law of synergistic effect of pre-tightening force and density of bolt on anchor is obtained by physical model test.The results show that the vertical stress in anchor increases with the increase of pre-tightening force,and the non-linear superposition of compressive stress in the middle of the free section of adjacent bolt in the anchor with a certain pre-tightening force produces synergistic effect.The axial compressive strength,modulus of elasticity,cohesion and internal friction angle are improved compared with those without anchor,and mechanical properties are affected by pre-tightening force and density.Although bolt support can improve self-supporting capacity,too many bolts will weaken the bearing capacity and stability of anchor.?3?The anchor model of bolt and rock mass is established by FLAC^3D numerical simulation software,and the influence law of bolt parameter and confining pressure on the stress field inside the bolt is analyzed.When two bolts act together,the stress far away from the bolt in the horizontal direction will"decrease first,then increase",and the effect of excessive pre-tightening force on the synergistic effect is not obvious.There is no stress overlapping area in the limited range,so increasing the length of bolt can effectively enhance the synergistic effect;the density of bolt needs to be reasonable;the density of the bolt is too small to have synergistic effect;the density of the bolt is too large to overlap the stress,which can not give full play to the role of each bolt.Increasing the confining pressure can enhance the synergy rate of stress field in the middle part of the lateral connection of two bolts,but it has a certain weakening effect on the stress value,stress transfer range and stress concentration of the bolt.Confining pressure does not change the distribution pattern of stress field;The stress field of anchor decreases with the increase of drilling angle,and the drilling angle of anchor also affects the synergy rate of stress field of anchor.When the drilling angle is 90 degrees,the synergy effect of anchor is the strongest and the synergy range is the widest.?4?Based on the principle of cooperative anchor control,the supporting mode and parameters of a mine roadway in Guizhou were optimized and improved,which improved the condition of large deformation of surrounding rock,large initial change rate and long deformation duration,improved the construction quality and effectively controlled the deformation of surrounding rock.