Behavior of passive single pipe pile in sandy soil

Abstract

This research focuses on studying the effects of soil movement on the behavior of an existing pile driven in sandy soil. A physical model has been manufactured to investigate the effect of construction of an embankment adjacent to free head single pile driven in sand of dry unit weight of 13.5 kN/m3. The model pile of diameter (D) of 10 mm are tested under two conditions of loading: loaded axially and without load. The model piles are instrumented with strain gauges along the embedded length to measure strains resulting from the soil movement. The embankment loads are applied at distances of 2.5, 5, and 10D from the edge of the pile. The results obtained from the model pile are: the lateral and vertical displacements at soil surface, the rotation at soil surface, bending moment profiles, pile deflection profiles, pile rotation profiles and shear force profiles. Some of these results are measured experimentally and others are calculated theoretically based on the measured strains. Based on the results of tests, it was found that the maximum soil reaction increased axially loaded piles by 43, 19, and 43%, when the embankment is at distances 2.5, 5, and 10D, respectively. The flexible pile provides more resistance to soil movement pressure and increasing the distance between the embankment and pile reduces the effects of embankment. The behavior of axially loaded pile is different than that of the pile without axial loading.

Simulation the Behavior of Passive Rigid Pile in Sandy Soil

“…In the soil reaction profiles, the maximum soil reaction with a negative sign is defined as soil movement, while the soil reaction with a positive sign is defined as soil resistance. Rigid piles with a short-embedded length are subject to soil movement more than flexible piles [33]. The increase in soil movement of the rigid piles in comparison to that of the flexible piles was 88%, 25%, and 0% for LP and increased by 329%, 110%, and 20% for UP at distances 2.5, 5, and 10 D, respectively, as shown in Figure 10.…”

“…The maximum shear force of the flexible LP was increased by 175%, 50%, and 33% compared to that of the rigid LP at distances 2.5, 5, and 10 D respectively. Also, the maximum shear force in the flexible UP was larger than that in the rigid UP by 200% and 25% at distances 5 and 10 D for the same reason, while at 2.5 D, the flexible UP moved through the soil due to the high soil movement pressure, which caused a reduction in shear force by 33% compared to that for the rigid UP [33]. The shear force depends on the reduction of the maximum bending moment with increasing distance between the model pile and the embankment, because this reduction comes from the decrease in resistance of the soil behind the pile due to soil movement, which means that the pile is subjected to more soil movement pressure.…”

“…Meanwhile for UP, the point of crossing was at a shallow depth, equal to 110 mm, and a distance of 0.3 mm from the original pile location because the piles were not loaded with any axial load. The rotation profiles show that the maximum rotation of the rigid LP was larger than that of the flexible LP by 177% at distance 2.5 D due to the increase in soil movement pressure, which caused more rotation in the rigid pile, while at 5 and 10 D the rotation of the flexible LP was larger than that of the rigid LP by 22% and 140% respectively due to the pile's flexibility and application of axial load [33]. The maximum rotation of the rigid UP was larger than that of the flexible UP by 725% and 52% at distances 2.5 D and 5 D respectively, while at 10 D the reverse was noticed.…”

“…The rotation at the soil surface of UP was decreased by (28-59) % by increasing the distance from 5 to 10 D because the pile was not restrained by axial load, where the pile moved toward the embankment. The maximum rotation of the rigid pile was more than that of the flexible pile by 156% at 2.5 D, while the maximum rotation at the soil surface of the rigid pile was less than that of the flexible pile by 28% and 88% at 5 and 10 D, respectively [33]. The bending moment profiles of LP are shown in Figure 6.…”

“…The displacement of the rigid unloaded pile was more than the displacement of the flexible pile by 45%, 32%, and 11% at 2.5, 5, and 10 D, respectively. The application of axial load to the head of the pile restrained the rigid pile more than the flexible pile, where the displacement of the loaded rigid pile was less than that of the loaded flexible pile by 6% and 42% at distances 5 and 10 D respectively [33]. The rotations at the soil surface of LP and UP at different distances between the embankment and the edge of the pile are shown in Figure 5.…”