Dynamic Behavior of Single Steel-Driven Vertical and Batter Piles under Horizontal Excitations: Field Model Testing

This paper presents the field test results for 3.3-m-long driven steel pipe single vertical piles, $P1(\beta =0°)$, and single batter piles, $P2(\beta =10°)$ and $P3(\beta =20°)$, for four different eccentric moments ($W·e=0.225$, 0,885, 1.454, and $1.944\mathrm{N}·\mathrm{m}$) under the static load ($W_s$) of 12 kN and 14 kN subjected to horizontal excitation acting both in the direction and transverse to the direction of pile batter. The field test results include the frequency-amplitude response, soil-pile separation length, distribution of dynamic bending moment, and dynamic axial load. The observed frequency-amplitude responses displayed nonlinearity in both the horizontal and rocking components of motion for all the piles. It was ascertained that with the increase in the pile batter angle, the resonant frequency increases, and resonant amplitude decreases. The test results also showed that batter piles generate lesser dynamic bending moment and higher dynamic axial load along the pile than the vertical pile. The frequency-amplitude responses from the field tests were compared with the theoretical prediction based on the continuum approach. It was found that the continuum approach with precise boundary zone parameters predicted the dynamic response of all the piles reasonably well in comparison to the dynamic field test results. It has been observed that the batter piles with loading direction in the direction of pile batter generate a substantial increase in the horizontal and rocking stiffness as compared to the batter piles with loading direction transverse to the direction of pile batter. Furthermore, the study highlights the normalized plots on the effect of pile batter angle, loading direction, eccentric moment, and static load on resonant frequency and resonant amplitude based on the theoretical and experimental studies.