Three dimensional finite element modeling for the laterally loaded passive pile behavior

Ekici, Anıl
In this study, some of the factors affecting the slope stabilizing pile response have been investigated by means of three dimensional finite element solution using PLAXIS 3D software. Three full scaled field experiments were modeled for the verification of the proposed 3D models. It was concluded that PLAXIS 3D can successfully predict the measured pile deflection and force distributions. Afterwards, a parametric study was carried out. Two series of analyses (i) studying the effect of the pile embedment depth and (ii) studying the effect of pile spacing were performed. Some of the conclusions of this study are: (1) There is a critical pile embedment depth necessary to provide sufficient pile resistance, and this depth depends on unstable soil properties and strength ratio of stable soil to unstable soil. (2) As piles get closer (smaller s/d), load on each pile decreases and soil arching increases (i.e. less flowing of the soil between the piles). So there is an optimum pile spacing by considering soil arching and group reduction phenomena. (3) For sandy soils, effect of soil arching significantly decreases for pile spacing ratios (s/d) larger than 6. Piles in group start to behave like individual piles approximately at s/d=8. Stronger soil arching develops at pile spacing ratios (s/d) between 2 and 4. (4) Significant group reduction develops when piles are closely spaced. Approximately 30% reduction was observed in lateral loads exerted to piles in group for s/d=2. Therefore, s/d=4 was seen to be more optimum value for an effective pile design.