PERFORMANCE OF PILE GROUP UNDER INCLINED CYCLIC LOADING IN SANDY SOIL

Abstract

ABSTRACT Many types of foundation exposed to periodic inclined loads resulting from different sources. These forces in turn affect the foundations of the structures. Therefore, there is a need to intensify laboratory and field studies to assess this issue. To study the effect of inclined cyclic loading on pile group, an experimental program with a small scale model can be used. Thus, this study displays assessment via small-scale models of pile groups embedded in sandy soil with Dr 70% to identify the behavior of this model while exposed to inclined load. The testing program involved examining the behavior of three models of pile groups with three configurations 2x2, 2x3, and 3x2 were slenderness ratio L/D of 40 with changing different parameters such as a number of loading cycles (1, 5, 25 ,50, 100), the effect of angles of inclination load i.e. (0o,15o, 30o, and 45o), (CLR) is the rate of cyclic load ratio (20%, 40%, 60%, 80% ), at frequency (0.2) Hz and the ratio of the spacing between piles (S/D) 3, 5, and 7. A new specially devised loading actuator was designed to achieve static and incline cyclic loading. The bending moment along the pile and lateral displacement of pile group head were measured VI It can seem that the piling group's displacement and the bending moment is increased with increasing cycle no.of loading cyclic for all spacing. Additionally, the lateral displacement of the pile group increased significantly when decreased the pile spacing from 7D to 3D. The group 2x2 showed decreasing in lateral resistance about (60%-77%) compared with other groups for all spacing. In addition, the lateral resistance of group 2x3 is less than group 3x2 for all spacing Also for all models, there is an accumulated in lateral displacement increase by increase CLR and for CLR=60% indicates the Critical Cyclic Load in100 cyclic. The inclined load would be divided into two components, i.e. axial and horizontal components, the axial component from the inclined load is working as the vertical load on the pile groups, and causing the increase of the stiffness of the piles group and decreasing the lateral deflection about (37%-75%) in the soil in front of the pile and this would be seen when the angle close to the vertical axis(i.e. 45o). It is significant to mention that the location of maximum bending moments; this position is usually at the upper portion of the embedded length of the piles for each row which equal 1/4L. Similarly, The pile group model (2x3) showed the behavior of bending moment is less than the model (3x2) by approximately (25%, 16%, 23%, 40%) for angles 0o, 15o, 30o, 45o respectively.