An equivalent-boundary method for the shell analysis of buried pipelines under fault movement

Abstract

A new shell finite element method (FEM) model with an equivalent boundary is presented for estimating the response of a buried pipeline under large fault movement. The length of affected pipeline under fault movement is usually too long for a shell-mode calculation because of the limitation of memory and time of computers. In this study, only the pipeline segment near fault is modeled with plastic shell elements to study the local buckling and the large section deformation in pipe. The material property of pipe segment far away from the fault is considered as elastic, and nonlinear spring elements at equivalent boundaries are obtained and applied to two ends of shell model. Compared with the fixed-boundary shell model, the shell model with an equivalent boundary proposed by the study can remarkably reduce the needed memory and calculating time.

Local Buckling Behavior and Plastic Deformation Capacity of High-Strength Pipe at Strike-Slip Fault Crossing

“…The equivalent boundary model was used to reduce the element numbers in numerical calculation by using few nonlinear springs simulating the axial constraints on pipe induced by the adjacent pipes, as show in Figure 4. Liu et al, developed the constitutive model of the equivalent boundary [54], which represents the relationship of the axial force F and the pipe extension at Point B ∆L (Equation (7)). …”

A new finite element model of buried steel pipelines crossing strike-slip faults considering equivalent boundary springs

“…Takada et al [9] used the shell model to simulate the pipeline behavior subjecting to the large fault movement. Liu et al [10,11] developed a shell finite element model to evaluate the mechanical response of pipelines crossing the active fault. Kokavessis and Anagnostidis [12] conducted a finite element analysis of the buried pipeline crossing the strike-slip fault, where the contact element was used to simulate the interaction of the pipeline-soil.…”

“…In such case, the fixed constraint is not fully accurate, because it neglects the interaction of the pipeline-soil beyond the model. To overcome the shortcoming, Liu et al [10] proposed an equivalent-boundary method to examine the mechan- ical response of pipelines under the fault displacement. However, a shortcoming can be still found in the equivalent-boundary method from Liu et al [10], i.e., the equivalent-boundary spring cannot be applied the segment where the pipeline yielding occurs.…”

“…In this paper, a new equivalent boundary spring is developed to overcome the shortcoming in Liu et al [10], and to simulate the interaction of the pipeline-soil beyond the model more actually. Correspondingly, a closed-form solution is derived to obtain the stiffness coefficient of springs.…”

Numerically Based Analysis of Buried GRP Pipelines under Earthquake Wave Propagation and Landslide Effects

“…Liu et al [19] presented an equivalent spring to model the boundary conditions of the pipe using the shell model in a fault. The work of Liu et al was to decrease the length of the pipe and replace the removed parts with equivalent springs.…”