The Machanical Behavior Study For Single Well Ventilation Type Shaft

The ventilation shaft in domestic long highway tunnel gradually increased in number,ventilation shaft application is crucial, but the experience on tunnel ventilation design andconstruction is still not mature, therefore researching for its mechanical behavior has animportant theoretical significance and is valuable in engineering applications. Based on theNO.2ventilation shafts of the world’s deepest Qinling Zhongnanshan extra-long highwaytunnel, this paper analyzed the mechanical properties of shaft clapboard structure by thegeneral software ANSYS, and analyses were mainly as follows:Firstly, based on domestic and abroad literature, this paper investigated and analyzedthe ventilation shafts built in our country on mature experience of the mining sector, and thenit concluded design and construction technologies for tunnel ventilation shafts and stresscharacteristics of reinforced concrete materials under high temperature in fire.Secondly, this paper built shaft clapboard structure finite element model and analyzed itsstress characteristics under normal operating conditions and fire condition. The resultsshowed that the shaft clapboard structure stress was less under normal operation ventilationconditions and it had more safety reserves, its stress was remain less under smaller firecondition and the structure could still meet the normal requirement, and its local tensile stresswas great under extreme fire conditions, but the probability of occurrence is minimal.Therefore the structural design of NO.2shafts was safe and reasonable. Shaft structure mainlybearded the compressive stress. There are tensile stresses in local position of air supplysurface inside shaft lining. Shaft lining was less affected by temperature stress. Centraldiaphragm was affected clearly by temperature stress. Air supply surface mainly bears tensilestress. Air drainage surface mainly bearded compressive stress. Stress concentration is easilyproduced in connecting parts between central diaphragm and shaft. Crack appeared in connecting parts between central diaphragm and shaft of shaft bottom section and well shapeunder extreme fire conditions.At last, this paper compared mechanical behavior of shaft structure in different operatingconditions and then putted forward reasonable safety recommendations for the futurestructure design and construction of shaft central diaphragm.