Experimental Analysis of Vertical Deformation and Bearing Characteristics of Bridge Piles in High and Steep Slopes

Abstract

More and more rigid frame bridges with high piers and large spans are built in the high and steep slope areas of deep valleys in southwest China. The slow deformation of the slope in the geological sense often causes the problems of piles, which in turn causes damage of the upper bridges. The vertical bearing characteristics of bridge piles in slope still need to be conducted because of the peculiarity of slope topography. The vertical deformation and bearing characteristics of piles in the slope area were experimentally studied by considering different influencing factors and the fitting formula for the ultimate bearing capacity of the piles under vertical load is obtained. The results show that the vertical deformation and ultimate bearing capacity (defined by vertical limit settlement deformation of 0.013 times the pile diameter) of the pile are closely related to its position in the slope. The pile in the middle of the slope has the lowest vertical ultimate bearing capacity. Moreover, the side frictional resistance transfer depth of the pile in continuous slope is greater than that of the pile in unilateral slope. Additionally, the slope angle has a significant influence on the vertical bearing performance of piles. The delayed settlement of the pile top decreases approximately 40% at most and the vertical ultimate bearing capacity of the pile increases 48.6% at most as the slope angle decreases by 15°. Meanwhile, the side friction resistance of the pile increases with the decrease of slope angle. The bending moment applied to the pile top reduces the vertical ultimate bearing capacity of the pile and increases the axial force of the pile body. The results can provide data support for pile design and instability judgment with similar geological conditions.