Seismic performance of graded energy dissipation damper for shield tunnel with variable mode

Abstract

A modal variable graded energy dissipation damper (GEDD) is proposed to solve the single energy dissipation scale and serious stiffness degradation of shield tunnel lining. The hysteretic model of GEDD is derived and established, presenting the fundamental design principle of GEDD and the subsequent design of parameters for its main energy dissipation unit. A fine 3D solid finite element (FE) model of GEDD, along with the tunnel joint equipped with GEDD, is constructed and subjected to seismic performance assessment. Results show that GEDD can dynamically adapt its damping force using two distinct energy dissipation modes—friction and bending—to effectively address varying levels of seismic activity, thereby accomplishing phased energy dissipation. The comparison between theoretical and numerical solutions for GEDD reveals minimal errors, attesting to the high precision of the FE model. In the bending energy dissipation stage, GEDD excels at achieving substantial stiffness recovery, with the potential to recover up to 398.81 % of the residual stiffness, demonstrating consistently high energy dissipation efficiency throughout. The average viscous damping coefficients for the friction section and the bending energy dissipation section are notably high, reaching 59.17 % and 35.14 %, respectively. Compared with standard joints, tunnel joints equipped with GEDD exhibit a remarkable reduction in maximum internal forces, registering a 71.37 % decrease. Additionally, the maximum damage factor for the concrete joints remains below 0.2. GEDD effectively combines high energy dissipation and stiffness recovery whilst mitigating damage to lining joints. These findings offer valuable insights for designing seismic damage mitigation measures in earthquake-prone areas for shield tunnel projects.