Full-scale experimental study of the dynamic performance of buried drainage pipes under polymer grouting trenchless rehabilitation

Polymer grouting technology is a cost-effective and trenchless method for repairing leakage and subsidence of drainage pipelines. This paper reports the results of a full-scale experimental approach in the field, where we tested the structural dynamic responses, before and after polymer grouting trenchless repairing, of a reinforced concrete drainage pipeline of 700 mm inner diameter buried in dense soil and subjected to both surface impact loads and driving loads. The dynamic changes of three types of pipeline-the normal pipeline, disengaged pipeline, and polymer-repaired pipeline-is reported in detail in this paper for different soil cover depths, types and magnitudes of loads, and locations. The results show that under the surface load of the soil, the pipe experiences compression at its crown and bottom and tension at its springlines on both sides; moreover, the circumferential stress is greater than its longitudinal stress. An additional impact load or driving load has its greatest influence within 3 m on both sides of its point of action. The bell and spigot joints are the most vulnerable places in the pipeline. There the vertical displacement is discontinuous and relatively large when extra loads are applied. The dynamic response of the pipeline is greater to impact loads than to actual driving loads of comparable magnitude. Uneven pavement also enhances the response of a buried pipeline to the surface traffic load. Pipeline disengagement has a substantial negative effect on the overall mechanical resilience of the pipeline. However, polymer grouting can repair a disengaged pipeline effectively, even restoring its mechanical behavior to that of a normal pipeline.