Research On Buried Non-metallic Pipe Detection Technology Based On Sound Wave Propagation Characteristics

The underground space is getting more and more crowded with increasing underground infrastructures such as electric cables and pipelines.Pipeline ageing,ruptures,and manual damage often result in pipe leakages.This leads to further widely application of trenchless buried object detection technology.At present,there are many products for cable and mental pipeline detection on the market and the detection accuracy meets the demand.However,non-metallic pipes are gradually replacing metal pipes because of their corrosion resistance and low cost.The detection technology for such pipes needs to be developed.Analysis of the current situation in China shows that the detection technology of non-metallic pipelines has problems such as single method,high cost and poor detection accuracy which affects the application and development of non-metallic pipeline detection technology.In the view of the shortcomings of non-metallic pipeline detection,the paper presents a theoretical study on an acoustic-based buried pipeline detection method combined with the vibration principle of thin-walled pipe structure and elastic wave dynamics.The main research contents are as follows:(1)Using the wave method to establish the coupled motion equation of buried liquid filled pipeline and then deriving the complex wavenumber expression of low frequency main propagating n=0,s=1(fluid-borne)wave;(2)Think of the soil around the buried pipe as an infinite space,the expression of soil displacement has been derived based on coupled equation of motion purposing to discuss the radiation of elastic wave;(3)Considering the layer characteristics of soil media,the displacement expression of the second layer of soil was derived and the influence of layered media on elastic wave propagation were discussed;(4)The COMSOL Multiphysics finite element analysis package was used to simulate the acoustic-structure coupling finite element analysis of two case which are the fluid-filled pipe in the infinite soil and the layered soil.The amplitude and phase cloud map of the soil displacement were obtained.The results were compared with the theoretical results to verify the accuracy of the finite element model;(5)The three-dimensional simulation model of buried fluid-filled pipeline was established by using COMSOL software to solve the soil displacement of each measurement point on the ground.According to the amplitude and phase of the displacement a detection technique of the buried pipeline was proposed.The research results show that the finite element simulation solution agrees well with the theoretical solution.The shear wave and compressional wave generated by the fluid-borne wave radiation interferes with each other.When the interference is strongest the soil displacement response is shown as a local minimum and the phase has an abrupt shift.The results of layered soil case shows that the stratification makes the frequency of the strongest interference reduce or increase.The spatial unwrapping phase of the ground displacement can detect the direction of the buried water supply pipeline.The amplitude of the ground displacement can detect the incentive source in the underground pipeline.The theoretical model and simulation model established in this paper laid the foundation for further research and played a positive role in the field of domestic buried pipeline detection.Figure [56] Table [3] Reference [54]...