Pipe-Soil Interaction at Pipe Bend under Seismic Load

Abstract

Owing to large differences in the stiffness of pipelines and soil, their movements cannot be coordinated under vibrational loads. Therefore, pipe-soil interaction is an extremely important factor in studying pipeline failure, and many researchers have performed detailed investigations on pipe-soil interactions in straight pipelines. In this paper, pipe bending tests were performed using unplasticized polyvinyl chloride (PVC-U) pipes on a shaking table and earth pressures at an elbow were obtained under different site conditions. Experimental results were compared with those obtained from particle flow code in two dimensions (PFC2D) simulations and empirical equations, which proved the reliability of the experimentally obtained results. In this paper, the change rule of earth pressure at an elbow was analyzed, relevant regular curves obtained for different soil types were fitted, and the relationship between earth pressure at an elbow and transverse and longitudinal earth pressures for straight pipes were determined. Then five external factors influencing the earth pressure of pipe bending, including pipe buried depth, pipe diameter, bending angle, loading frequency, and loading peak, were investigated. Finally, based on experimental equations of earth pressure for straight pipes, experimental equations were derived for elbow earth pressure calculation, and the reference values for the calculation of the earth pressure of pipe bending were given.