Threats of Design and Implementation of Tunnels Shafts in Passive Defense Point of View

Shaft as a main member of underground structure and tunnel, has a basic role in stability, durability and structure workability according its utilization in critical condition. It is a vertical or inclined structure with different utilities such as air ventilation, installation canal, emergency exit, shortcut way, ore extraction and emergency access in crucial situation. The main usage of shaft in tunnel and each underground structures, is providing of Fresh air inlets for people and equipments and exhausts which designed and constructed according to overburden, kind of project, condition of usage, number of people and equipments in form of vertical or inclined shafts form the basis of tunnel ventilations. Since the seeing the tip of the shaft at ground level, according to overburden, morphology and topography, is the disadvantage of the project and the source of the threat and on the other hand, enemy produces his weapons according to our ability to build safe structures. In this article we tried to analyze the shafts as tunnel vulnerabilities, in order to evaluate the ways of reducing vulnerability, Improve efficiency and increase safety and providing practical solutions and passive defense solution such as good site selection, regard the principles of CCD, Increase the safety factor of the structure span of the shaft, Creating failure, Diversion and construction of damper in vertical and inclined shaft In order to reduce the effect of shock waves to prevent or decrease possible damages.