Evaluation of geocomposite compressible layers as induced trench method applied to shallow buried pipelines

Abstract

Abstract This paper suggests as a rather simple and innovative alternative of the induced trench method with the use of geocomposite replacing EPS geofoam for protection of shallow buried pipes. Laboratory model tests and the numerical studies have been conducted on induced trenches constructed with relatively thin drainage geocomposite, as compressible layers, placed into sand. A parametric study using numerical modelling was conducted considering different arrangements of compressible layers in order to optimize the use of these geosynthetics in rehabilitation and maintenance of shallow buried pipes. It was concluded that geocomposites have compressibility enough to replace EPS using diminished area, which favor the applicability for shallow pipelines protection. Reduction on vertical soil pressures over the crown of the pipe reached values of 90%. The stress reduction at the crown was found to be significant affected by the width of the geocomposite and its distance from the crown of the pipe. The use of a more compressible condition of sand backfill provide more efficiency as far the geocomposite is from the crown of the pipe. Results from numerical modelling also indicate that using more than two geocomposite layers led to negligible stress reductions compared to one layer solution.