Chaidul Haque Chaudhuri

Failure of pipelines below road pavement results to the disruption of both the traffic movement and the consumers of the pipelines. Intermediate safeguard layer can be used to protect the pipeline from heavy traffic loads. The present study proposed analytical solutions to obtain the dynamic response of buried pipe below road pavement with and without considering safeguard based on the concept of triple and double beam system respectively. Pavement layer, safeguard and the pipeline are considered as Euler Bernoulli’s beam. Advanced soil model is used (viscoelastic foundation with shear interaction between springs) to model the surrounding soil. Self-weight of soil is also considered in the present study. The obtained governing coupled differential equations are solved adopting finite sine Fourier transform, Laplace transform and their inverse transformation. The proposed formulation is initially verified with the past numerical and analytical studies and then validated with the three-dimensional finite element based numerical analysis. From parametric study it is perceived that the stability of the pipe can be significantly increased by providing intermediate barrier. Further, pipe deformation is increases with increasing traffic loads. At very high-speed range (> 60 m s⁻¹), pipe deformation is significantly rises with increasing traffic speed. The present study can be useful in preliminary design stage before performing rigorous and expensive numerical or experimental study.

The present study proposes a closed-form analytical solution for investigating the behaviour of buried adjacent pipeline subjected to ground heave induced from static pipe bursting underneath. The governing differential equation of the adjacent pipe is derived based on the concept of a beam (both Euler–Bernoulli's and Timoshenko's beam) resting on a Pasternak foundation. A Fourier series is used to solve the governing differential equation. The proposed solution is validated with the results obtained from earlier full-scale experimental works and finite-element-based numerical study. Further, a parametric study is conducted to investigate the influence of relative pipe–soil stiffness and pipe–pipe intersection angles on the adjacent pipe response during the pipe bursting process. It is perceived that normalised maximum pipe deformation reduces and normalised maximum pipe bending moment increases as the value of the relative pipe–soil stiffness increases. Further, for the present case, the maximum pipe curvature is obtained at a 35° intersection angle. Hence, it is understood that a 90° intersection angle is not always the critical criterion. The study will be useful in the preliminary design stage for obtaining quick and relevant results without performing rigorous numerical or experimental study.

The current study derives a closed-form analytical solution of buried pipeline subjected to underground blast load. The solution is derived considering Euler Bernoulli’s beam resting on viscoelastic foundation. In viscoelastic foundation, shear interactions between individual Winkler springs are considered. Soil pressure on the pipeline resulting from the self-weight of the soil above the buried pipeline is also incorporated in the present analysis. The finite sine–Fourier transform is employed to obtain the solution for the governing differential equation. The proposed formulation is validated with the results obtained from the past centrifuge model test, finite-element-based three-dimensional (3D) numerical analysis and simplified analytical study. Further, a parametric study is performed to obtain the impact of trinitrotoluene (TNT) charge weight, standoff distance, damping ratio, and flexural rigidity of the pipe-on-pipe response. From the results of the parametric study, it is noticed that peak pipe deformation increases with increasing the TNT charge weight and decreases with increasing the magnitude of standoff distance, damping ratio, and flexural rigidity of the pipe. The proposed formulation can be adopted in the initial design stage for rapid estimation of buried pipe responses subjected to underground blast load.

For buried pipelines, it is not always possible to avoid active zones where there is a possibility of ground deformation either due to earthquake or topographical reasons, and hence it is necessary to understand the impact of ground deformation on buried pipelines. The present study derives a semianalytical solution for the case of a buried pipeline subjected to spatially distributed horizontal transverse ground deformation (HTGD). Governing differential equations are developed considering the pipe as a Timoshenko beam and surrounding soil as a two-parameter foundation. Firstly, the proposed semianalytical solution is validated with prior studies on the influence of HTGD on buried pipelines, and then a comprehensive parametric variation with various influential parameters such as peak ground deformation, pipe diameter, wall thickness of pipe, burial depth, backfill soil, width of HTGD zone, and type of HTGD pattern is studied to understand the effect on the behavior of buried pipelines. It is observed that the pipe stability increases with increasing the width of the HTGD zone and with decreasing peak ground deformation. Pipe responses significantly vary with the pattern of HTGD. Further, pipe failure against HTGD can be reduced by reducing pipe diameter or by increasing the pipe wall thickness and by providing loose backfill material. The present methodology will help to evaluate the displacement patterns of pipes and the qualitative behavior of an overall soil–pipe system subjected to spatially distributed HTGD without performing numerical analysis.