This study analyzed seismic responses of shallow rectangular tunnels within the framework of soil-structure-soil interaction. The idealized soil profile and properties were derived from site-specific investigation reports. Racking curves, typically used in design, were reevaluated to reflect local soil conditions, nonlinear soil behavior, and seismic influences. Results differed significantly from traditional literature findings, emphasizing the importance of localized factors. Finite element methods enabled nonlinear soil parameter modeling and time-history analysis of soil-structure systems. Literature reviews and case studies identified potential damage states with discrete damage levels. The findings quantified probabilities of these damage states and established recurrence relationships for system damages. Fragility curve analyses, widely employed in structural engineering, were used to develop graphical representations of damage probabilities. This study's outcomes provide insights into the seismic behavior of tunnels under localized conditions and enhance reliability in geotechnical and structural engineering designs.

The demand for tunnels in densely populated urban areas is growing rapidly to address mobility challenges. Mechanized tunneling is widely adopted in urban environments due to its high productivity and the relatively small ground deformations it induces. However, urban tunneling is highly complex because of the typically shallow depths and interactions with aboveground structures. Therefore, accurately predicting ground deformations induced by mechanized tunneling at the design stage is crucial for assessing potential building damage. To investigate these deformations, a series of centrifuge tunnel tests have been conducted at academic institutions such as the Universities of Cambridge and Nottingham to study the behavior of shallow mechanized tunnels in cohesionless soil. These tests serve as excellent benchmarks for numerical model calibration. Once calibrated to replicate centrifuge test results, numerical models can efficiently analyze a wide range of scenarios at a fraction of the time and cost. This paper investigates ground deformations induced by shallow tunneling in cohesionless soil using numerical models calibrated against selected centrifuge tunnel tests, which encompass varying tunnel diameters, depths, and sand relative densities. The numerical modeling results presented in this paper provide extensive insights into tunnel behavior, illustrating how tunnels respond to different relative densities and depths under tunnel volume losses of up to 5%, approaching failure conditions. Additionally, a comprehensive analysis of ground deformations caused by shallow tunnels in sandy soils and their potential impact on buildings is presented.

Tunnel construction in urban areas may result in ground deformations that pose a risk to existing buildings and infrastructure; thus, accurate prediction of these induced ground deformations during the design phase is crucial. The paper focuses on the effects of sandy soil relative density on the ground deformations induced by tunnels excavated with Tunnel Boring Machines (TBMs). The study utilizes the Finite Element Method (FEM) and the NorSand model to simulate the behavior of a sandy ground. The validity of the FEM modeling approach is established by comparing predictions with results from six centrifuge tunnel tests from the literature. The centrifuge tests were performed on sand at different relative densities, tunnel diameters, and tunnel depths. The parameters for the NorSand model were determined based on laboratory tests. Only the state parameter was modified to achieve the desired relative density in the numerical simulations. The effects of relative density observed in centrifuge tests (Franza et al., 2019) have been numerically reproduced with no further adjustments of the model parameters. The rich outputs from the numerical models enabled an in-depth investigation of tunnel behavior, yielding new insights into how tunnels respond under varying relative densities, depths, and diameters. A comprehensive analysis of the induced ground deformations caused by shallow tunnels in sandy ground and the potential to damage buildings is included.

The main theoretical principles used in the mathematical modeling of the interaction of the soil mass and the lining of a tunnel of circular cross-section, constructed under the protection of a shield made of pipes in a closed way in close proximity to the earth's surface. A formulation has been made and an analytical solution has been obtained for a plane elasticity theory problem on the equilibrium of a geomechanical system, including a weighty semi-infinite region containing arbitrarily located solid washers and a circular hole supported by a ring, simulating a soil mass, cross-sections of protective shield pipes and the lining of a tunnel. The boundary conditions of the problem reflect the action of gravitational forces in the mass and the presence of full contact at the boundaries of regions with different deformation characteristics. To solve the problem, the theory of functions of a complex variable, the mathematical apparatus of complex Kolosov-Muskhelishvili potentials and Laurent series were used. This solution, which makes it possible to determine the components of the stress tensor at any point in each of the considered areas, is the basis for the method of lining a tunnel constructed using a protective shield made of pipes.