Experimental and Numerical Study of Influence of Vertical Load on Laterally Loaded Single and Group Piles in Layered Sand

This paper presents the results of an experimental and numerical study conducted on laterally loaded single and group piles embedded in two-layered sand in the absence and presence of vertical load. This study analyses the changes in lateral displacement and bending moment in pile foundations under combined vertical and lateral load. Pile embedment length was varied to study the effect of pile stiffness. Experimental results were validated with three-dimensional numerical analysis performed using finite element based software Plaxis 3D. Results indicated that lateral capacity of single piles decreases and bending moment increases in the presence of vertical load. Whereas, presence of vertical load resulted in increased lateral capacity and decreased bending moment in group piles. Effect of vertical load was more detrimental for lateral capacity of flexible piles. A generalized equation was developed for pile lateral capacity under combined load in terms of pile capacity under lateral load, normalized lateral displacem ent, pile embedment ratio, number of piles in a group and ratio of sand layer thickness to pile embedment length. Empirical relationships between normalized lateral displacement and ratio of vertical load to lateral load were derived for single and group piles. Lateral displacement equal to 20 % of pile diameter is produced in single pile and pile group when ratio of vertical load to lateral load is 2.3 and 3 respectively. Equations for relationship of normalized lateral displacement with inclination of resultant load were also derived.