Influence of shear effects on the characteristics of axisymmetric wave propagation in a buried fluid-filled pipe

Abstract

The acoustic propagation characteristics of axisymmetric waves have been widely used in leak detection of fluid-filled pipes. The related acoustic methods and equipment are gradually coming to the market, but their theoretical research obviously lags behind the field practice, which seriously restricts the breakthrough and innovation of this technology. Based on the fully three-dimensional effect of the surrounding medium, a coupled motion equation of axisymmetric wave of buried liquid-filled pipes is derived in detail, a contact coefficient is used to express the coupling strength between surrounding medium and pipe, then, a general equation of motion was derived which contain the pipe soil lubrication contact, pipe soil compact contact and pipe in water and air. Finally, the corresponding numerical calculation model is established and solved used numerical method. The shear effects of the surrounding medium and the shear effects at the interface between surrounding medium and pipe are discussed in detail. The output indicates that the surrounding medium is to add mass to the pipe wall, but the shear effect is to add stiffness. With the consideration of the contact strength between the pipe and the medium, the additional mass and the pipe wall will resonate at a specific frequency, resulting in a significant increase in the radiation wave to the surrounding medium. The research contents have great guiding effect on the theory of acoustic wave propagation and the engineering application of leak detection technology in the buried pipe.

Application of the Differential Evolutionary Algorithm to the Estimation of Pipe Embedding Parameters

“…Lu et al [ 14 ] introduced the pipe–soil contact state variable into the fluid-dominated axisymmetric wave equations for the first time, which broke through the assumption of the extreme buried conditions, and the general wave equation of the axisymmetric wave of the buried liquid-filled pipe is obtained as follows:…”

“… represents the contact coefficients to the actual boundary conditions at the pipe–soil interface, among which represents compact contact, and represents lubrication contact. The other parameter details in Equations (1)–(7) are given in reference [ 14 ].…”