Monitoring Measurement And Numerical Simulation On Highway Tunnel Shafts That Inhale And Exhaust Gas Though One Shaft

At present, the number of highway tunnel ventilation shaft construction are very few, and the experience of designs and construction is not yet mature. In this paper, based on ventilation shaft No. 2 in Qinling Zhongnanshan highway tunnel which is the largest and the second longest tunnel in the world, we carry out the research of highway tunnel ventilation shaft structural mechanics-type state ,the main results are as follows:At first, we investigate the documents at home and abroad, and carry out the research of the highway tunnel ventilation shaft that have been completed , and take into account mining industry department's mature experience in building wells, and sum up the related technologies of China's highway tunnel ventilation shaft in the designs and construction.Secondly, we carried out monitoring measurement in the 2nd shaft of Qinling Zhongnanshan highway tunnel to get the force of the second lining structure and the middle mode structure. The second lining structure has evener stress than the middle mode structure. The compressed stress and the tensile stress of steel bar in the second lining structure are generally less than 40MPa and 20MPa, the compressed stress and the tensile stress of concrete in the second lining structure are generally less than 2MPa and 1MPa . The compressed stress and the tensile stress and of steel bar in the middle mode structure are generally less than 50MPa and 30MPa, the compressed stress and the tensile stress of concrete in the middle mode structure are generally less than 2MPa and 1MPa . When the construction plane is 80m from the second lining structure of the monitoring section , is 130m from the middle mode structure of the monitoring section, the second lining structure and the middle mode structure can not be affected, and the stress situation is stable .Finally, we see the force in the condition of the self-stress and thermal stress by finite element analysis method, the results show that the stress of the shaft structure is mainly compressive stress, the compressed stress and the tensile stress of the Shaft wall structure are generally less than 10MPa and 1.5MPa, the compressed stress and the tensile stress of the middle mode structure are generally less than 5MPa and 2MPa . Stress concentration usually exist in the attachment point between of the shaft wall and the middle mode . The influence ofthe middle mode is obvious by thermal stress . The surface of enters and exhaust the gas are affected by tensile stress and compressed stress, the influence caused by thermal stress is smaller in the shaft wall.By contrast, monitoring measurement results and the finite element method calculated results are basically the same. During the construction and post-operational phase,the force of ventilation shaft on the 2nd is smaller, and the safety reserve is enough. The result show that the design is reasonable, and construction program is feasible, and the structure is safe.