Impedance functions of a strip foundation in presence of a trench

• Published in: European journal of environmental and civil engineering Vol. 26; no. 8; pp. 3509 - 3546
• Main Author: Terzi, Vasiliki G.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 11-06-2022
• Subjects: Foundation impedance functions; soil and foundation dynamics; trenches; wave propagation
• ISSN: 1964-8189; 2116-7214
• DOI: 10.1080/19648189.2020.1805023

The influence of a trench in the behaviour of a rigid, strip foundation is numerically investigated under the prism of impedance functions. Both the soil and the foundation are simulated by 2-D plane strain elements. The soil half-space finite element model is truncated using absorbing boundaries. The foundation has three degrees of freedom: vertical and horizontal translation and rotation. Therefore, the foundation is excited by: vertical and horizontal force and moment loading for various frequencies. The corresponding displacements are generated by the finite element code. Finally, a 3 × 3 impedance matrix is calculated in the frequency domain applying FFT (Fast Fourier Transform). The vertical translation is uncoupled, whilst the horizontal translation and rotation are coupled. Various cases of
are examined, where
is distance between the mid-point of the strip foundation and the mid-point of the trench and
is the foundation's half-width. The finite element model is validated for: screening of waves; impedance functions. Parametric analyses are conducted for a three-degree of freedom system. The existence of an open trench significantly affects the behaviour of the foundation. The foundation's response depends on: the superstructure; the foundation's inertia; the distance and type of the trench.