Articles
Publication Date: 2024
International Journal of Structural Stability and Dynamics (2194554)25
Proper modeling of the dynamic behavior of the soil significantly affects the accuracy of the soil-structure interaction analysis results. Using nonlinear constitutive models has the highest accuracy in modeling soil behavior under earthquake loading. However, it is not functional for practical engineering purposes because of the high cost and complexity. The equivalent linear method also has many limitations, such as filtering out the high-frequency components of the input excitation, underestimating surface ground motion over long periods, and considerable error in high soil strain levels. The current study aims to present an accurate, simple, and low-cost method to model the nonlinear behavior of clays. This method does not meet the limitations of the traditional methods and fully considers the effect of the influential parameters. The novel central composite design technique was adopted to evaluate the effect of influential variables on the nonlinear behavior of clay and formulate the proposed method. The introduced method is applicable to various building structures, power planets, etc. Numerical analyses performed on the proposed method and nonlinear modeling confirm the accuracy, efficiency, and generality of the proposed method. © 2025 World Scientific Publishing Company.
Publication Date: 2024
Geomechanics and Engineering (20926219)39(2)pp. 115-129
The present paper aimed to estimate the ground surface settlement induced by excavated circular tunnel in soft soils, taking into account the uncertainties of geometric and geotechnical parameters. To this end, following two-dimensional numerical simulation of the tunnel based on finite difference method in FLAC2D, the ground surface settlement profiles were determined using regression analysis (Gaussian equation). The effect of changes in tunnel geometric parameters (including buried depth C, diameter D and depth distance H of tunnel) and soil geotechnical properties (including modulus of elasticity E, undrained shear strength Su and density γ) based on three dimensionless ratios named depth ratio (C/D), soil strength ratio (γD/Su) and the soil stiffness ratio (E/Su) were studied on the ground surface settlement. The results showed that there is a relationship in the form of Smax/H = f (γD/Su, E/Su, C/D) between the parameters to determine the normalized ground surface settlement induced by tunnel. Therefore, using the gene expression programming (GEP) algorithm and forming a database containing 1000 different simulations in terms of a combination of C/D, γD/Su changes for fixed E/Su ratios (inputs) and Smax/H results (outputs), two powerful empirical equations were proposed as new empirical models to estimate the normalized maximum ground surface settlement. © 2024 Techno-Press, Ltd.
