Study On Choosing Of Initial Support Of New Types In The Loess Road Tunnel

Aiming at the the problems of loess tunnels,such as deformation was large with long duration,insufficience of supporting structure, broken lining,which is cause by the insufficient acknowledge of the loess’ characteristics,such as the large deformation,the process of deformation is long duration.Therefore the research on higher strength and rigidity of initial support form has important practical significance.Considering concrete-filled steel tube has the advantages of high bearing capacity,convenience of construction,efficiency and ecmonics,so researcher makes a replacement between concrete –filled tube frames and section steel frames,and then explore the applicability of the frame in loess tunnel.The three principal conclusion is followed:(1) As a new type of initial support and comparing to section steel frame concrete filled steel tube frames is more adaptable to cater the need of loess high way tunnel of strenghth and rigidity.Through the numerical simulation,concrete filled steel tube frames is more fit for the construction of loess high way tunnel and have better effectiveness.(2) In provided condition,the initial support of the concrete-filled steel tube of specified thickness has greater strenghth and rigidity than section steel frame and it lead to smaller deformation.(3) Comparing to the section steel frame,the cecondary lining under the initial support of the concrete-filled steel tube bear smaller bending moment and axial force,at the same time,the safety factor of specified section has apparent improvement.