Research On Stress-Relief Under Control And Creep Control Of Soft Rock Roadway In High Stress

Along with mining depth's increase, the high stress soft rock tunnel's support and the maintenance question appear to be more and more prominent, exploring the correct soft rock distortion mechanism and the surrounding rock control theory becomes an urgent question to be solved. For this reason, according to the domestic and foreign research existing state and the geological condition of Gu Hanshan colliery in Jiaozuo mining area, based on analysis of stress-relief and soft rock creep mechanism, do research on stress-relief support for one time under control and secondary creep control technology in high stress soft rock tunnel, confirm the parameter of stress-relief support for one time under control and secondary creep control technology, and apply the research results to the project practice successfully.In view of the traditional support have helpless predicament to the high stress soft rock tunnel, from the angle of controlling deformation of surrounding rocks, proposed once loosening and stress-relief of gangue dropping technology. On basis of this technology, considered that the advantages and disadvantages of stress-relief to maintain the tunnel, proposed once stress-relief support under control, through the control of stress-relief degree, may display the superiority of stress-relief, reduces the disadvantages to high stress tunnel support.Take advantage of radial stress at the boundary of surrounding rocks has difference between after and before gangue dropping, established the mechanical model of once stress-relief support under control, fluctuating law of plastic zone as well as stress shift along with stress-relief frequency is consistent with energy of deformation release rule, confirmed the theoretical model's reliability of once stress-relief support under control; According to this model and based on the strain softening condition and the Kastner formula's computation supposition, have inferred the plastic deformation pressure formula, proposed the concept of"limit plastic zone radius"based on the inflection point in distortion pressure curve, the reasonable stress-relief degree is the plastic zone radius should next to the"limit plastic area radius", which has provided the theory basis of how to get the reasonable"degree"for stress-relief under control.Used the strain softening model in FLAC numerical calculus software to analyze intensity attenuated function in surrounding rocks by release of pressure, explained the distortion mechanism in surrounding rocks of stress-relief under control reasonably, and combined the theory and the numerical analysis to confirm reasonable parameter of once stress-relief under control. By analyzing the creep mechanism of soft rock, proposed the essence and goal of creep control in high stress soft rock tunnel, and based on this, have established the elastic-viscoplasty mechanical model of creep control. By using this model made elastic-viscoplasty analysis on secondary masonry-lining support and secondary anchor rod and grouting reinforcement, and confirmed reasonable support style as well as parameter of creep control.Support parameter which obtained from the theory and numerical analysis, used once stress-relief under control (the totally enclosed I iron circular support + full face stress-relief of gangue dropping) + secondary creep control support technology (secondary anchor rod and grouting reinforcement) to carry on the engineering test in the west main tunnel of Gu Hanshan colliery, controlled the fierce distortion and continued creep of this tunnel effectively, and this support plan is simple, convenient, had the high promotion and application value.