Evaluation method for structural stability of large diameter air shaft engineering constructed by raise boring machine
A stability evaluation method for vertical shaft structures considering the characteristics of reverse drilling technology was proposed to address the issue of surrounding rock stability during the expansion of large-diameter raise boring engineering.And it as determined that,the surrounding rock self-stability is the key factor.Based on the strength reduction method,a quantitative evaluation method of the surrounding rock self stability ability of the shaft wall with the surrounding rock stability coefficient as the core was proposed,and the surrounding rock stability coefficient k0 under the extreme self stability state of the surrounding rock is determined by numerical simulation.To solve practical engineering problems,engineering treatment measures was proposed to prevent instability at the empty side.During the drilling stage,temporary support operations while drilling were implemented to achieve rapid closure of the surrounding rock.Finally,taking the return air underground shaft project of Lijiahao Coal Mine as the research object,the local instability risk assessment opinions are put forward,and the accuracy of the assessment is verified based on the engineering practice.The results show that the assessment conclusion is consistent with the actual results.
Raise boringvertical shaftstrength reduction methodventilation shaftsurrounding rock self stabilization
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