Study on Seismic Response and Vibration Reduction of Shield Tunnel Lining in Coastal Areas

Abstract

The construction of subway tunnels in the coastal section is affected by special soil quality, with complex construction conditions of unstable soil and vulnerability to groundwater corrosion. The design difficulty of subway tunnels is greatly increased, and the safety performance in the event of an earthquake is greatly reduced. To study the changes in shield tunnel lining structure under earthquake and propose damping measures, ANSYS software is used to conduct tunnel soil numerical simulation. Firstly, static analysis and modal analysis are carried out, and it is found that the maximum displacement deformation occurs at 3.8 cm of the arch crown, and the maximum stress occurs at 2.6 × 107 Pa of the left and right wall corners, 8 easily deformed points are obtained at the same time. Input EI_Centro EW forward 19 s seismic wave is used to analyze the displacement, acceleration and stress vibration characteristics of tunnel lining. The upper part of the lining is more vulnerable to earthquake, and the right arch waist is subject to the maximum stress, reaching 1.37 × 10−4 Pa, the maximum displacement deformation point is 3.65 × 10−10 m at the right wall. To reduce the impact of earthquakes on tunnel lining, the damping scheme of adding an isolation layer is adopted. Using foam concrete isolation material can reduce the stress of the arch waist by 74.6%, and rubber isolation material can reduce the stress by 80%. In consideration of groundwater corrosion and subsequent engineering construction, it is recommended to use foam concrete as the material for the isolation layer. This study can provide a theoretical basis for the design of metro tunnels in offshore areas.

Analysis of Different Earthquake Records on the Behaviour of Circular Tunnel in Sandy Soil

“…A study carried out on concrete pipe behavior during seismic shaking showed that, linear elastic and Mohr-Coulomb models had lower bending moments than hardening soil and hardening soil with small strain stiffness models [12]. Results of ANSYS for numerical simulations showed that, arch crown deformation at 3.8 cm and wall corner stress at 2.6 x 10 7 Pa [13]. A study on Delhi metro tunnel behavior under various dynamic loading cases showes that, combined earthquake and train motion cause larger displacements in soil and forces in tunnel liners compared to individual loads [14].…”

“…Fig 13. show the absolute maximum horizontal displacements for monitoring points as the percentage ratio of tunnel diameter (δx/D%) for different soil states under static load and earthquake records.…”

Study on the Seismic Response Characteristics of Shield Tunnels with Different General Segment Assembly Methods and Widths

“…This is of central importance for seismic design in the case of metro systems, considering their significance for life safety and economy and that they are generally more vulnerable in soft-soil ground conditions [9]. With regard to the seismic resistance of shield tunnels in areas with soft soil, researchers have conducted a range of investigations, mainly focusing on the dynamic response of tunnel structures under complex soft-soil ground conditions with different earthquake intensities and site conditions and the corresponding seismic design measures [10][11][12]. However, the tunnel lining structure is simplified to a homogeneous circumferential ring in the above study, only the overall performance of the segment ring is taken into account, and the weak link of the shield tunnel connection is not taken into account, which is somewhat different from the actual structure.…”