Seismic interaction analysis of deep excavation- piled foundation in soft soils

Abstract

Dynamic interaction analysis of deep excavation-piled foundation in soft soils is studied. In this contribution, deep excavation is considered to be adjacent to the piled foundation. In fact, the interactive influences of a deep cavern and a piled foundation is studied. Loose sands and soft clayey layers are considered. Also, due to the significant effects of the pore water pressure on the soil strength, all sequences of excavations are accompanied with the seep analysis. In order to investigate the seismic effects of the excavation, time history analysis is performed. Therefore, the susceptibility of the loose sand layers to the soil liquefaction is studied. Due to the fact that frequency domain analysis is more acceptable that time domain analysis for transient phenomena, soil liquefaction is controlled in frequency domain analysis. Frequency domain analysis is considered using Fast Fourier Transform. In fact, the frequency domain informations of a saturated loose layers are compared in two different of stages. So, the frequency domain data for seismic ground response, before and after the excavation is shown to predict the soil liquefaction. All results demonstrate the meaningful influences of the excavation on the soil behavior and the structural piles. The results show that the structural beams, might fail due to the additional internal forces which are exerted on the piles during excavation stages.

Keywords

• deep excavation
• cavern-piled foundation interaction
• frequency domain analysis
• soil liquefaction
• fft