Seismic Response of Tunnels in Soft Soil under Various Earthquakes

Hegazey, Ahmed Sayed; Hafez, Kamal Mohamed; El Kamash, Waled H.; Moubarak, Azza Hassan

doi:10.21608/pserj.2025.368225.1399

Seismic Response of Tunnels in Soft Soil under Various Earthquakes

Document Type : Original Article

Authors

¹ Civil Engineering Department, Suez Canal University, Ismailia, Egypt

² Geotechnical, Foundation Engineering Department, Faculty of Engineering, Suez Canal University, Ismailia, Egypt

³ Civil Department, Faculty of Engineering, Suez Canal University, Ismailia, Egypt

10.21608/pserj.2025.368225.1399

Abstract

Earthquakes can cause significant damage to infrastructure or buildings. This study investigates the seismic response of segmented tunnels through numerical analysis under various earthquake conditions. The research examines ring and longitudinal behavior at 10m depth using four distinct loading scenarios: static lining phase and three earthquake events(Petrolia, Elcentro&Geysers). The behavior of a shallow tunnel in soft soil is simulated using PLAXIS 3D. The tunneling study employs a constitutive model based on typical implementations of the hardening soil model (HSM). The settlement effects are as follows: the settlement was more significant for the Petrolia earthquake than the El Centro earthquake. Vertical displacement analysis shows a maximum displacement of 299mm due to Petrolia earthquake loading. The longitudinal analysis demonstrates complex wave propagation effects, with maximum moments occurring at approximately 12m length and significant variations between 20-40m. The results show that high-frequency earthquakes, such as the Petrolia earthquakes, induce considerable alterations of pore water pressure and cause significant settlement of soft soils. In addition, it is determined in the study that, given the same driving force, an earthquake of different magnitudes has different characteristics to initiate the deformation of the tunnel lining, and the deformation of the tunnel's crown is the largest. The results highlight the critical importance of seismic loading characteristics in tunnel design, particularly in soft soil conditions.

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