عنوان مقاله [English]
Underground structures and openings are some of the most important parts of the infrastructure of modern urban facilities, and are used for a wide range of applications, including subways and railways, highways, material storage, and sewage and water transport. Historically, underground facilities experience a lower rate of damage than surface structures under severe environmental conditions, such as earthquakes. Nevertheless, some underground structures are in deposits surrounding city grounds and have experienced significant damage during past earthquakes. This study presents a summary of the current state of seismic analysis and design for underground structures. In general, seismic design loads for underground structures are characterized in terms of the deformations and strains imposed on the structure by the surrounding ground, often due to the interaction between the two. In the pseudo-static analysis approach, the ground deformations are imposed as a static load and the soil-structure interaction does not include dynamic or wave propagation effects. In the dynamic analysis approach, a dynamic soil structure interaction is conducted using numerical analysis tools, such as finite element or finite difference methods. Recently, due to considerable improvement in different numerical methods and computer capabilities, the dynamic analysis of soil surrounded structures has been improved dramatically. In this paper, it is intended to evaluate the dynamic plain strain behavior of a two-dimensional tunnel model, via umerical analysis of finite difference by software FLAC 2D (Fast Lagrangian Analysis of Continua). In this research, the depth of the tunnel or the overburden effects on the tunnel lining is considered in the analysis. These lead to increased thrust force, shear force, bending moment, compressive stress, tension stress, and shear stress in the tunnel structure; consequently, increasing levels of structural damage. Numerical analysis results are compared with analytical solutions that include two methods; Wang and Penzien. Finally, according to the results of some analytical models, it shall be deduced that the results of analytical solutions have some discrepancies with the two mentioned methods (Wang and Penzien solutions).