Influence of segmental joints on tunnel lining behavior

Abstract

Underground Construction has to higher standards and regulations for safety designs than others. To reduce construction time and number of supports, tunneling shield could be applied to many underground construction projects especially in soft ground area. Because of limitation of working space, segments lining must be assembled on site by steel bolts. Segmental joints, weak point on lining, will be occurred by this method. Because the lost due to collapse of structure is very high, it is necessary to investigate the capacity and behavior of underground tunnel. However, lining behavior depends on many parameters such as earth pressure, geometry and stiffness of structure. Therefore, this study tries to separately consider individual parameters list like number of segmental joint, diameter of lining, earth pressure and stiffness of segmental joint. In practice, evaluation of the structure capacity should be limited in elastic range to maintain a value of safety factor. In this study is composed of three programs: 1. Numerical method, Finite element, to predict behavior of structure 2. Full-scale testing of two segments which are connected by steel bolts 3. Plastic models are one-fortieth in size of the full-scale structure. The models are composed of full section and half section. Both the full-scale and plastic models are tested by two point load method. The results show stiffness of segmental joint, number of segmental joint, earth pressure and diameter of lining directly effect to rigidity of lining structure. Finally, information is used to develop adaptive design code of underground structure.