Physical Model on Deformation Behavior of Super-Large Pile Group

Lizigou long-span Bridge which adopts super-large pile group is one of the main projects on the Neijiang-Kunming railway in China. A physical model of the super-large pile group is developed to gain a better understanding about its mechanical behavior by observing the distribution of internal forces and of its deformation behavior under vertical loads, horizontal loads and their combined loads. Under vertical loads, the middle piles are subjected to the maximum vertical load and the axial force at the lower part of the pile is much smaller than that at the upper; with the load increasing, the lateral friction resistance of a pile body increases gradually from the lower part to the upper part. Under horizontal load, the mechanical behavior at the upper part of a pile is affected significantly by loads and the maximum bending moment occurs at the zone adjacent to the platform, and the value of bending moment is decreased nonlinearly along the pile from top to bottom. The mechanical behavior of the soil along the horizontal load direction has a difference between the front and the back of the pile. The bending moment's variation tendency along the piles and its extremum. values differ from the condition of the applied loads such as the combination of vertical and horizontal loads.