The use of TBM for excavation and construction of tunnels such as subways, roads, and railroads, etc. in urban areas and access tunnels in underground mining are rapidly increasing. Yet, design of segmental tunnel liners are based on empirical and analytical methods. These methods ignore the influence of type of inter-segmental joints and variations of stress distributions in cross-sectional areas of the segmental liners, and hence, they cannot predict realistic structural behavior of the support systems. This paper deals with three-dimensional finite element analyses of the segmental tunnel lining for two conditions; segmental lining models with bolted-joints; and with non-bolted. For construction of the required model, ABAQUS Finite Element software was used in which the surrounded ground is represented by radial linear-elastic springs. The final results of the analyses illustrated that the displacement decreases whilst stress increases in bolted-joint condition compared with the non-bolted one. Though, this stress increase does not cause the lining failure under static loading condition.
Shield tunneling has become a well-established tunnel construction method in various ground conditions. The shield tunnel is lined by reinforced concrete segments through the use of connecting bolts [1]. The contact plane between each two adjacent circumferential segments, in a single ring is indicated as an inter-segmental joint. Due to the radial and tangential deformation of the segmental lining, employing flexible joint is strongly recommended. To prevent the concrete and gasket damage, the load in segmental joint must be small [2]. The inter-segmental joint controls the greater part of the global lining behavior. Proper understanding of the joint behavior helps to an improved understanding of the realistic tunnel lining behavior which is essential for tunnel engineers to design a tunnel structure in a more accurate and safe approach. Most of the previous numerical modeling dealing with this type of problem has been based on two-dimensional models which lead to problems of reduced complexity [3], [4]. For example Muir Wood[5] investigated the segmental lining behavior as a homogeneous ring, Mansour[6], Abu-Krisha[7] and Ding et al.[8] studied the influence of different parameters such as face pressure, grouting pressure, material characteristics of the soil and depth of cover of the tunnel, Hefny et al.[9] considered the behavior of jointed tunnel lining and Teachavorasinskun[10] studied the effect of joint on moment of lining. Also Zhang & Koizumi[1] investigated the load bearing capacity of key-segment based on experimental test results. Former researchers seldom dealt with the 3D modeling of segmental lining like Klappers et al [11], Chen&Mo [12], [13]. Different theoretical models were developed to describe the joint behavior with the aim of getting realistic analytical and numerical lining models. For example, a simple theoretical model for describing the moment-rotation behavior of the inter segmental joints was developed by Gladwell and later by Janssen[2]. The moment-rotation behavior in the segmental joint derived by Janssen takes into account only linear-elastic material behavior [14]. Using this idea the inter-segmental joint will collapse after having reached the maximum linear-elastic capacity [2].
