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Lack of geological and tectonical knowledge in a region causes hazard in project implementation. There are many examples related to this issue in Iran and the world. Main purpose of this research is to analyze the fractures because of their importance and effect on the implementation of engineering and civil engineering projects such as Khansar-Boien Miyandasht tunnel. For this purpose, the process and density of the fractures and their spatial-geometric position were investigated. Therefore, joints and faults in the Khansar syncline area and the site of Khansar-Boien Miyandasht tunnel were collected, then processed by interpreted in the software such as Stereo32 and Georient. According to the result, a group of joints can be related to pre-tectonics, another one can be related to syn-tectonics(folding and faulting) and some fractures are related to the post-tectonics . Geomechanically, syn-tectonic fractures are extensive in depth and these issues are very important, so it should be considered in implementing the project of Khansar tunnel. Results of the geological engineering study such as, uniaxial strength test, point loading, Schmidt hammer, and ultra-sonic Test were showed high-resistance massive orbitolina limestone , and alternation of shale , limestone , medium-resistance limestone and black slates include low resistance that lead to apply the supports with higher safety factor. Considering the tunnel direction (NNE-SSW), high slope fractures and tunnel tensions, it is possible to create sliding wedges in the left wall and left ceiling of the tunnel. Therefore, tunnel drilling should be performed cautiously by blasting method.

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