EFFECT OF GEOCELL REINFORCEMENT IN THE MITIGATION OF TRAFFIC LOADS TRANSMITTED TO THE FLEXIBLE BURIED PIPES

Abstract

Buried pipeline systems are commonly used to transport water, sewage, natural oil/gas and other materials. They are classified as lifelines since they carry essential materials for the support of human life. Dynamic vertical loads like traffic loads present a severe hazard for these systems. Although there are some standards and instructions for design (e.g. ASTM D 2321-08; BSI, 1980), installation and maintenance of buried pipes, nevertheless backfill material optimization needs to be studied, particularly in the case of geocell-reinforced backfill material. The present study presents the results of laboratory model tests conducted on small diameter PVC (Poly Vinyl Chloride) pipe, buried in geocell reinforced sand beds. The aim of the study is to evaluate the suitability of the geocell reinforcement in protecting the underground utilities and buried pipes from the dynamic traffic load. A PVC pipe with external diameter 110 mm and thickness 1.4 mm was used in the experiments to simulate the buried pipe. The vehicles dynamic load was simulated by applying the load on the top a steel plate placed on the surface of the sandy soil with the help of a manufactured physical model. A series of laboratory model tests has been performed to study the behavior of geocell-reinforced sand under dynamic load. It was found that The optimum burial depth of the geocell (u) beneath the footing and the appropriate width of the reinforcing under dynamic loads were approximately 0.1 and 3.2 times the footing width (B), respectively, (i.e. u/B = 0.1 and b/B = 3.2). In general, reinforcing the sandy soils with geocell leads to a beneficial reduction in dynamic response (surface settlement, displacement amplitude, and transmitted dynamic pressure) for all soil states in different percentages. This is accompanied by an increase in soil strength, as well as, reduces the hazards of traffic load.