Seismic analysis of deep tunnels in near fault conditions: a case study in Southern Italy

Abstract

The importance of underground structures in transportation and utility networks makes their vulnerability to earthquakes a sensitive issue. Underground facilities are usually less vulnerable to earthquakes compared to above-ground structures, but the associated risk may be relevant, since even a low level of damage may affect the serviceability of a wide network. Seismic analysis of tunnels close to seismogenic faults is a complex problem, which is often neglected at the design stage for the lack of specific codes or guidelines for the design of underground structures in seismic conditions and also because, as mentioned above, underground structures are considered less vulnerable to earthquake loading. This paper investigates the seismic response of deep tunnels focusing on the required steps for a proper design under both static and dynamic loading. The study aims at contributing to improve the methods currently used for the seismic analysis of underground structures.\ud At this purpose, the seismic response of a deep tunnel in Southern Italy has been investigated along the transversal direction. The infrastructure is part of the railway switch line connecting Caserta to Foggia in the Southern Apennines which is one of the most active seismic regions in Italy. The seismic response in the transversal direction has been analysed by using the pseudo-static approach as well as through advanced numerical modeling using the spectral element method coupled with a kinematic approach for finite fault simulations.\ud The pseudo-static approach has been implemented using a closed-form analytical solution

Analysis of cylindrical tunnels under combined primary near-fault seismic excitations and subsequent reverse fault rupture

“…Beside these studies, there are some studies on impact of both permanent fault displacement and strong ground motions or each one individually. To mention a couple, Anastasopoulos et al (2008a) and Corigliano et al (2011) studied the behavior of tunnel in near field conditions. In the first research paper, the authors parametrically explored three possible segment lengths with two types of joint for a 70 m deep immersed tunnel.…”

Dynamic behavior of NATM tunnel under harmonic loading

“…Many researchers have been studied the effects of presence of underground structures on the ground settlement and drift responses by using physical and numerical modeling [2][3][4]. Due to the complexity of the soil-structure interaction and effects of the pseudo-static deformation of the ground on the seismic behavior of the under-ground structures, the ground strains (ground displacements) govern the under-ground structures seismic responses [5]; Therefore, using an advanced soil constitutive model such as soil hardening model (HS) is inevitable to simulate the soil-structure interactions correctly. In this study, a series of dynamic analyses were performed on a 2-lane NATM tunnel using soil hardening constitutive model and harmonic loading with different PGA.…”

Reinforcement of Underground Excavation with Expansion Shell Rock Bolt Equipped with Deformable Component

“…Most underground structures are essential to human life and include many utilizations: pipelines for water, sewage, gas, electricity and telecommunication; subways; underground roads. For these reasons it is very important to study how tunnels are damaged during earthquakes to protect human life and the service efficiency [7], [20], [38]. Many deep civil tunnels in Switzerland, China, and Peru have experienced rockbursts to various degrees.…”