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Geomechanics and Engineering
  Volume 25, Number 3, May10 2021, pages 221-231

Modified Lysmer's analog model for two dimensional mat settlements under vertically uniform load
Der-Wen Chang, Ming-He Hung and Sang-Seom Jeong

    A two dimensional model of linearly elastic soil spring used for the settlement analysis of the flexible mat foundation is suggested in this study. The spring constants of the soils underneath the foundation were modeled assuming uniformly vertical load applied onto the foundation. The soil spring constants were back calculated using the three-dimensional finite element analysis with Midas GTS NX program. Variation of the soil spring constants was modeled as a two-dimensional polynomial function in terms of the normalized spatial distances between the center of foundation and the analytical points. The Lysmer's analog spring for soils underneath the rigid foundation was adopted and calibrated for the flexible foundation. For validations, the newly proposed soil spring model was incorporated into a two dimensional finite difference analysis for a square mat foundation at the surface of an elastic half-space consisting of soft clays. Comparative study was made for elastic soils where the shear wave velocity is 120~180 m/s and the Poisson's ratio varies at 0.3~0.5. The resulting foundation settlements from the two dimensional finite difference analysis with the proposed soil springs were found in good agreement with those obtained directly from three dimensional finite element analyses. Details of the applications and limitations of the modified Lysmer's analog springs were discussed in this study.
Key Words
    soil stiffness, mat foundation, flexural displacement, modified Lysmer's analog model
Der-Wen Chang and Ming-He Hung: Department of Civil Engineering, Tamkang University, #151 Ying-Chuan Road, Tamsui District, New Taipei City 25137, Taiwan

Sang-Seom Jeong: School of Civil and Environmental Engineering, Yonsei University, 50 Yonsei Ro, Seodaemun Gu,
Seoul 03722, Republic of Korea

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