Abstract:

In order to solve the nonlinear problem of dynamic loss of soil around the pipe during the collapse development process of the buried pipeline, first, a numerical analysis method was used to construct a nonlinear coupling model of pipe-soil that passes through the collapse zone. Then, the model was verified based on experimental measured data and specifications. Finally, a study on the damage mechanism of buried pipelines subjected to soil collapse was carried out, and the dynamic evolution process and mechanical characteristics of buried pipeline collapse were discussed. The results show that the axial stress is the control stress, the mid-span pipe bottom is the control point, the mid-span section is the dangerous section, and excessive tensile stress is the main reason for failure of buried pipelines. It is confirmed that "pipe-soil separation" phenomenon exists. When the collapse depth reaches 48 mm, "pipe and soil separate", as the collapse process progresses, the entire process of pipe-soil structure from the beginning of deformation to the tensile failure of buried pipeline can be divided into three stages: the top pressure stage, the transition stage and in the bottom tension stage, the collapse depth of 80 and 160 mm is the dividing point. When the collapse depth reaches 59 mm, the pipe top stress changes from valley to peak at mid-span position. When collapse depth reaches 80 mm, friction stress appears.

Key words: cell life and death, buried pipeline, soil collapse, pipe-soil separation, soil loss