Designing, analyzing, and experimentally verifying a uniaxial shear box for investigating the length effect of buried pipelines during soil liquefaction

Abstract

During an earthquake, buried pipelines can be threatened by various factors such as fault movement, ground motion, and soil liquefaction. Among these, fault movement and ground displacement have been identified as the most direct causes of pipeline fracture and rupture, as evidenced by previous earthquake disasters. While numerous studies have focused on the failure modes and mechanisms of pipelines crossing faults, little attention has been given to the dynamic uplift behavior of buried pipelines during soil liquefaction. To address such an issue, this study designed a uniaxial shear box to investigate the dynamic characteristics of buried pipelines during soil liquefaction. The box dimensions are 3600 mm × 1000 mm × 1100 mm and can embed a pipeline specimen of 3000 mm in length for testing. The seismic input motion direction is designed to be consistent with the axial direction of the pipeline to avoid lateral input motion influence. This study used DEEPSOIL analysis software to investigate whether the response of a uniaxial shear box under conditions of dry sand and saturated sand is consistent with theoretical analysis results. In addition, a preliminary test was conducted to ensure compliance with the requirements of subsequent pipeline tests, specifically on the uplift behavior of buried pipelines. The results showed that the soil dynamic responses under both dry sand and saturated sand conditions were consistent with the DEEPSOIL analysis software results. Furthermore, the pipeline test results verified that the input motion did not generate additional forces on the buried pipeline, but did indeed trigger soil liquefaction and cause the pipeline to uplift. These findings demonstrate that the uniaxial shear box designed in this study meets the design requirements and can be used to investigate the dynamic response of buried pipelines subjected to soil liquefaction under the influence of length effects in future studies.