Reduction of stresses on buried flexible pipes by using compressible material

The design of structures such as buried pipes and culverts requires an understanding of soil - structures interaction. The loads acting on the buried pipes are measured differently from the load acting due to the soil arching. In flexible pipes, due to the vertical deflection of the pipe, the soil prism on the pipe is more settlement than the soil prism on the sides of the pipe. Therefore, with the positive soil arching that develops, some of the load that will come on the pipe is transferred to the side soil prisms and the load on the pipe decreases. In rigid pipes, the acting loads on the pipes increases with the negative soil arching. Imperfecth trench method has been developed to reduce the loads on rigid pipes. With this method, compressible material is placed on the pipe and artificially positive arching is achieved. By applying the imperfecth trench method in flexible pipes, the existing arching effect is increased. In this thesis study, field experiments carried out within the scope of the Deep Burial Project, which was designed to examine the behavior of large-scale HDPE and PVC pipes under thick filling loads, were modeled in Plaxis 2D program. In these created models, EPS geofoam material was used as a compressible material on the pipes. The thickness, width and density parameters of the EPS material were changed and their effects on pipe behaviors were examined. The use of thicker filling loads, the use of clay material as back filler material and the use of small diameter pipes are other cases examined with EPS geofoam material. In addition, apart from the use of EPS material on the pipe, analyzes were carried out by using it around the pipe. As a result of the performed analyses, the stress values that effected on the pipes and the deformation rates occuring in the pipes were determined. In the case of maximum improvement of pipe behavior by using EPS on pipes under 30 m filling load, 60% improvement in stresses acting on the pipe crown, 70% improvement in stresses acting on the pipe sidewall was achieved.