Three-dimensional finite element analysis of laterally loaded bridge caisson foundations in gravelly soil
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RESEARCH PAPER
Three-dimensional finite element analysis of laterally loaded bridge caisson foundations in gravelly soil Jiunn-Shyang Chiou1 • Jia-Qi You1 Received: 20 September 2019 / Accepted: 18 April 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this paper, we propose a three-dimensional finite element model that can simulate the caisson foundation behavior in gravelly soil. The soil model adopts a combination of the porous elastic model and the modified Drucker–Prager/Cap model for simulating the gravelly soil. For avoiding problems in laboratory testing on gravel specimens, a practical approach is proposed to determine and calibrate the parameters of the soil model using results of field geotechnical tests, such as a shear wave velocity profile, strength parameters of direct shear tests, and pressure–displacement curves of vertical and horizontal plate loading tests. The proposed finite element model was applied to simulate in situ lateral load tests on bridge caisson foundations in gravelly soil. Using the calibrated soil model, responses of caisson displacement, caisson head rotation, and soil displacement analyzed were observed to be in agreement with the measured responses. Caisson and surrounding soil responses were also investigated in detail. Keywords Caissons Finite element method Gravelly soil In situ tests Lateral loads
1 Introduction Caissons are a type of deep foundations with large cross sections and are commonly used in bridge structures in Taiwan. A deep foundation is generally vulnerable to lateral loading because its lateral resistance is lower than the vertical resistance. There are less studies on in situ fullscale lateral load tests for caisson foundations, especially in gravelly soils. In 2010, the National Center for Research on Earthquake Engineering of Taiwan conducted a series of lateral load tests on the old Niu-Dou Bridge in Ilan County, Taiwan [2, 4]. The bridge was constructed on caissons in gravelly soil. Results of the load tests are valuable for investigating the real performance of caisson foundations under lateral loading and for developing the associated analysis methods. In engineering practice, the Winkler beam model is a popular method for analyzing the lateral response of pile & Jiunn-Shyang Chiou [email protected] 1
Department of Civil Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.C.
foundations [5, 14, 16–19, 22]. When it is applied to caisson foundations, empiricism is sometimes used to determine the spring properties in the caisson spring model because of various types of subgrade reactions. Gerolymos et al. [7, 8] developed a four-component caisson spring model and utilized finite element modeling to create formulas of spring properties for cohesive soil. Moreover, for the aforementioned Niu-Dou Bridge load tests, determining spring properties for gravelly soils was challenging because no appropriate empirical formulas wer
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