Abstract A three-dimensional refined finite element model was established, which was used to investigate the me? chanical properties of three-inclined bolts in longitudinal joint of large diameter shield tunnel segment under the effect of different axial pressures. The changes of the distribution of cracks, vertical displacement, joint opening, joint ′s rotation angle, and bending stiffness were revealed. The results show that the cracks including the compressive cracks, through tensile cracks at the inner edge of the hand hole and the bolt hole on the joint surface, and oblique cracks at the side appeared in the segment under the action of positive bending moment. Whereas the cracks including compressive micro cracks and tensile cracks appeared at the bolt hole of the joint surface under the action of negative bending moment. The appearance of two cracks running through the width direction corresponds to the inflection point of the three mechanical characteristics curves, which includes the vertical displacement of joint, the compressive strain of concrete, joint opening, and rotation angle. The curve changed from approximately linear to nonlinear with the increase of bending moment. The joint′ s rotation angle changed to a nonlinear change when the concrete was crushed. The increase of axial force could delay the occurrence of crack penetration. The change of bolt stress could be divided into three stages under the action of the bending moment of joint, i. e., linear growth stage, nonlinear growth stage, and yield stage. The rapid growth rate of bolt stress was affected by the bending moment and axial force. The bending stiffness of joint had no obvious change at first, and then decreased. The increasing axial force made the bending stiffness of joint larger.
Abstract：
A three-dimensional refined finite element model was established, which was used to investigate the me? chanical properties of three-inclined bolts in longitudinal joint of large diameter shield tunnel segment under the effect of different axial pressures. The changes of the distribution of cracks, vertical displacement, joint opening, joint ′s rotation angle, and bending stiffness were revealed. The results show that the cracks including the compressive cracks, through tensile cracks at the inner edge of the hand hole and the bolt hole on the joint surface, and oblique cracks at the side appeared in the segment under the action of positive bending moment. Whereas the cracks including compressive micro cracks and tensile cracks appeared at the bolt hole of the joint surface under the action of negative bending moment. The appearance of two cracks running through the width direction corresponds to the inflection point of the three mechanical characteristics curves, which includes the vertical displacement of joint, the compressive strain of concrete, joint opening, and rotation angle. The curve changed from approximately linear to nonlinear with the increase of bending moment. The joint′ s rotation angle changed to a nonlinear change when the concrete was crushed. The increase of axial force could delay the occurrence of crack penetration. The change of bolt stress could be divided into three stages under the action of the bending moment of joint, i. e., linear growth stage, nonlinear growth stage, and yield stage. The rapid growth rate of bolt stress was affected by the bending moment and axial force. The bending stiffness of joint had no obvious change at first, and then decreased. The increasing axial force made the bending stiffness of joint larger.
CUI Qinglong1 LI Jin1 GAO Binyong2 XIONG Xinyue2
.Mechanical Properties of Three-inclined Bolts in Longitudinal Joint of Large-diameter Shield Tunnel Segment[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(5): 63-71
2022, Vol. 59 