Small Section Extra-long Tunnel Construction Technology Research In Inclined Shaft To Main Hole

The paper based on Tianping Railway Liu Panshan Moping inclined shaft andmain hole cross-section tunnel under construction,adopting numerical simulatinganalyses the stability of the inclined shaft to the main hole in cross-sectionconstruction,the main works and research achievements as follows in paper:(1)The inclined shaft to the main hole under construction,excavation the inclinedshaft causes stress and displacement of rock in the range of3times of the diameter ofthe tunnel,and the effect of the acute angle side is bigger than the blunt angle side of thecross-section rock,the stress concentration coefficient between2-3;the vault isinfluenced bigger than the arch waist and the arch foot in the cross-section rock;at theacute angle side of cross-section rock due to following tunnel construction in both freestate,the displacement direction of rock will change.(2)The different tunnel excavation on the stress and displacement of rock willproduce different effects;for the stress of cross-section rock,the CD method is betterthan the full face method and the bench cut method;for the displacement ofcross-section rock,the CD method is less than the full face method and the bench cutmethod in vault settlement quantity of rock,and the bench cut method is less than thefull face method and the CD method in arch waist level convergence of rock.(3)The different rock grade is not a big impact on stress of the cross-section rock;but with worse and worse quality of rock,the rate of change in the displacement of rockis accelerating trend, and Ⅳ grade is Ⅲ3times, Ⅴ is Ⅳ4times.(4)Through the stress and displacement of the cross-section rock field monitoringshows that:the stress and displacement of rock in the excavation initial stage,rate of change and variable quantity are very big,and along with the tunnel face far away,theygradually reduce,and the trend is basically same with calculated value,only the finalvalue has certain discrepancy.This is because the numerical calculation for the model insome assumption,rock parameters in consistent with the actual,therefore,the numericalcalculation is only”quantitative analysis,qualitative application”.