Soil-structure interaction of buried pipes under cyclic loading conditions

The safety of lifelines, as the most important urban facilities, under different conditions highly depends on the safe design and performance of these buried structures. This cannot be achieved unless their actual behaviors are well realized and considered at the designing stage. To study the behavior of buried pipes under different loading conditions, a new physical model was developed in Amirkabir University of Technology. The model is capable of simulating and monitoring flexible pipes under different conditions. The depth and the position of the buried pipes as well as the type and density of the surrounding soil can be changed and controlled. The cyclic loads with different amplitudes, and cycles as well as the monotonic loads can be generated and applied on the soil surface. The generated load can be applied on the pipe centrally or eccentrically. The radial deformations of the tested pipes as well as the shear and normal stresses on the boundaries of the soil trench were measured by a special probe and data acquisition system developed for this model. A series of different tests were carried out to study the soil-pipe interaction. The main factors affecting the behavior of these buried structures were studied and described in the paper. Among them the soil density and the pipe depth proved to be the most important factors affect the soil-pipe interaction. The influence of the impact at the first cycle was also found one of the main factors affecting the pipe behavior. There are also many other results the descriptions and discussion about which are given in the next sections.