Abstract:Lizigou large-span bridge which adopts super-large pile group is one of the main projects on the Neijiang—Kunming railway. A model for super-large pile group is developed to study the mechanical action,the distribution feature of internal force and deformation behavior of pile group under horizontal load. Through the model test,some dependence and magnitude of cross section bending moment of piles and horizontal displacement are obtained under different load levels. It is shown that the upper part of pile is affected significantly by the load,the maximum bending moment occurs in the vicinage of cross-connecting of pile and bearing platform,and the value of maximum bending is decreased progressively alone the pile from top to bottom. The mechanical action of the front and rear earth of pile group is different alone the direction of load.