Pipe response in a geocell-reinforced trench and compaction considerations

Heavy traffic loading can produce loss of functionality in pipeline networks, with consequential interference with economic and social impacts in the areas involved in breakage. The consequences of breakage or disconnection of pipelines are technical, economic and social. In the case of a sewer network failure, illness and epidemics might result. In this paper, to protect the buried pipe, use of a three-dimensional geosynthetic (geocell) is investigated to reinforce the trench. Two series of three-dimensional full-scale tests under repeated loadings have been performed. The first test programme compares the performance of buried pipes installed beneath soil that is unreinforced, planar reinforced, or with geocell in a trench. Compaction difficulties necessitated a change in the process of compaction so that a second installation was proposed. In this series of tests, further understanding of the behaviour of geocells with different opening areas and heights above the buried pipes under repeated loads is presented and discussed. It is observed that the effective reinforcement and improvement of the backfill system is achievable if the geocell is installed in the backfill with an appropriate compaction process. The results further indicate the importance of compaction both below and above the level of the geocell installation. As a result of the modified compaction process, the trench reinforced with geocell showed superior performance, delivering a 65% and 35% reduction in soil surface settlement and vertical diametral strain, respectively, compared with the unreinforced soil.