On Wellbore Support Structure Stability Under Freezing Condition
When the upper section of the main inclined shaft of No.1 well in Chagannaoer Coal Mine in Inner Mongolia Autonomous Region is constructed by freezing method,the surrounding rock forms high expansive surrounding rock pressure after encountering thaw water,which leads to the deformation and serious damage of the straight wall semi-circular arch support structure.In order to solve the problem of insufficient support force in the original support scheme,FLAC3D is used to model the original support scheme,and the deformation mechanism of the original support scheme is analyzed.Based on this,a double-layer shaft wall support scheme with horseshoe-shaped section is proposed,and the ultimate bearing capacity of the new scheme is calculated.The displacement of the roof and floor,the displacement of the two sides and the stress value of the original scheme and the new scheme are compared and analyzed.Results show that the double-layer shaft lining support form of horseshoe-like section can achieve the effect of resisting high expansive surrounding rock pressure and inhibiting bottom heave.
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