Composite Strength Of Cure-in-place Sewer Pipe

Cure-in-Place Pipe(CIPP) is a pipe rehabilitation method without excavation. In this technology, the new liner is turned into the old pipe with pressure and combined with old pipe by resin. Therefore, it will form a composite pipeline which has relatively high strength. The new liner can reduce the friction resistance of inner surface of pipe, improve the delivery capacity and cover the dirt. For the strength calculation of this composite pipe, it includes the remained strength of old pipe, the strength of liner and the strength composite pipe. Currently, researchers had the study of first two parts. However, it was lack of the theory of the strength calculation of composite pipeline.This dissertation is based on the combined thick walled tube theory, and develops the calculation method of CIPP. The conclusions achieved in this paper show in following:1) Itanalyzeddamage form of the concrete pipelines.2) In this paper, it summarized four methods of remained strength of old concrete pipeline. These methods include criterion method, D-M method, method of elastic-plastic mechanics and semi-empirical method of fracture mechanics. The paper discussed the remained strength calculation methods of old concrete pipe with axial and circumferential flaw.3) The main destruction forms of the lining after in-situ repaired concrete pipelines are stability and strength destruction. Based on the strength theory of axial and circumferential model, it built liner failure strength theory. Moreover, based on the buckling theory, it developed the capacity theory of stability.4) Through the strength analysis of composite pipeline, the strength calculation of the composite pipeline after in-situ repaired can be obtained by the different destruction forms of lining and old concrete pipelines.The theory above can be used to calculate the carried capacity of the double-layer or multi-layer composite pipelines.