STUDY ON SUPPORT EFFECT OF EARLY CLOSURE METHOD OF MOUNTAIN TUNNEL BASED ON DATA OF CONSTRUCTION WORKS

Abstract

 The early closure tunnel construction method can restrict deformation around tunnel face by inner pressure induced in immediate ring closed supports of tunnel section. In this paper, the characteristics of early closure method on inner support pressure, acting earth pressure, distance of closure and ratio of radius of support to invert are clarified.
 As a result, the support effect of early closure method is heightened by arranging the distance of closure according to ground characteristics, and earth pressure ratio of arch to invert has a correlation. These lead the guide of rationalization of support system.