Study On Pressurization Test Principle Of Pipelines With Free-surface

In order to maintain the sustainable development of economy, protect the environment and improve the living standard of people, urban drainage systerm is developing fast and becoming complicated. To avoid the pollution of groundwater resource and adjacent environment caused by drainage pipe leakage, current criterion in our country stipulates that there must be a pressurization test before drainage pipes are used. Two commonly used methods of pressurization test of pipelines with free-surface in best common are close water test and close gas test.The method of close water test has been used for a long time, so richer experience has been achieved. However, it not only takes pains and time, but also consumes raw materials during the close water test because of miscellaneous working procedures such as bricklaying in the two ends of pipe, water-repellent layer plastering, maintaining and water offletting, brick-block backouting after the test, especially in the region short of water and some drainage pipe with prop-pipe construction. In order to satisfy the fast development of municipal construction, new detection methods should be developed. One of those new methods is close gas test, which is not perfect yet and needs further developed.In this paper, hydromechanical theories, three-dimensional unsteady turbulent finite volume model and PHEONICS software are adopted to simulate the pressure field and the velocity field of the drainage pipe in allusion to the actuality of the necessary pressurization test before being used. Then analyze the computational results and figure out the variational rules of pressure and velocity with different leakage location while close water test or close gas test is applied. In the simulation of close water test, varied profiles of velocity of flow are obtained at different leakage location along the detected pipe, the variety values of the water level in the check well are acquired with time, consequently the location of the leakage can be judged. In the simulation of close gas test, the location of most possible leakage of pipe is judgedaccording to the changing speed of gas pressure at difference leakage positions.We have further knowledge in the leakage rule according to the numerical simulation on close water test and close gas test of pipes with free-surface ,which will provide useful reference for close water test and close gas test of pipes with free-surface in the future.