EXPERIMENTAL STUDY ON PIPE-SOIL INTERACTION USING FIBER OPTIC SENSING AND DIGITAL IMAGE ANALYSIS

In the process of urbanization and industrialization in China, the dependence and demand for underground pipelines are increasing, but a series of catastrophic accidents of underground pipeline have occurred in recent years. Therefore, it is urgent to emphasize the study on pipe-soil interaction and failure mechanism. In this paper, based on the quasi-distributed fiber Bragg grating(FBG)technology, a series of plane-strain model tests are conducted in laboratory. The fiber optic strain sensors are employed to investigate stress and deformation characteristics of buried pipes under the action of surface loading. A calculation method of earth pressures around the pipe is proposed based on fiber optic strain measurements. Meanwhile, the particle image velocimetry(PIV)technique is used to obtain the soil deformation around the pipe. Such deformation results are compared to the fiber optic monitoring results. The test results show that the FBG technology can effectively capture the distribution of earth pressure acting on the buried pipe and the evolution of soil strains. The deformation and failure patterns of soil are quite different for pipes with various burial depths. With the increase of burial depth, the soil arching effect becomes more significant. The conclusions drawn in this paper provide useful reference for evaluating underground pipeline hazards and improving monitoring and early warning levels.