Abstract: n order to analyze the sensitivity of influence factors on interlayer separation of complex roof，size of construction surface and interlayer separation was simulated by orthogonal experiment which had six factors with each factor having five levels that was original rock stress，rock properties of complex roof，tunnel width，rock thickness of complex roof，cohesion and internal frication angle of construction surface．The results showed that tunnel width and rock thickness of complex roof had obvious influence on interlayer separation and construction surface separation，with the increase of tunnel width and decrease of rock thickness of complex roof，the size of interlayer separation and construction surface separation linear increased．Rock properties in certain range had some influence on interlayer separation and more influence on construction surface separation．Internal frication angle and cohesion of construction surface had little influence on interlayer separation and construction surface separation．

Key words:  , interlayer separation；construction surface separation；orthogonal experiment；sensitivity analysis  , interlayer separation；construction surface separation；orthogonal experiment；sensitivity analysis