This paper describes the effects of local deformation, dent, and strain hardening properties on strain capacity in compression of a buried pipe.
There were a few cases that the dents were found on the gas pipeline in Japan. Axial compression buckling experiment was conducted using the dented pipe and produced data such as stress-strain curves. Next, an analysis model that can reproduce the experimental results was established, and conducted various parameter studies. Those studies were the change in the depth of the dent, the internal pressure of the pipeline, earth pressure, and ground spring. The seismic integrity of the buried pipe was described in considering the depth of the dent, internal pressure, earth pressure and ground spring.
It is generally known that with regard to the structures supported by considering large-scale foundations, input loss effect is expected due to the soil-pile interaction. Researchers, including some of the authors, have proposed a method for evaluating the input loss effect using the seismic deformation method that is generally used in design practice, and have shown its applicability to pile foundations with a pile diameter of about 1.5 m or less. On the other hand, when the flexural rigidity of the foundation body is large, such as the caisson foundation, the effective input motion may be amplified at low frequencies. Therefore, we generalize the seismic deformation method, then propose a method for evaluating both the amplification of effective input motion and the input loss effect by extending seismic deformation method. Furthermore, the validity of the proposed method is confirmed by comparing with the dynamic analysis results of the ground-structure integrated type for caisson foundations and rigid frame viaducts.
One of the characteristics of the damage to the expressway embankment damaged by the recent earthquake is that there are many cases of joint openings, sediment outflows, and steps on the culverts. For these damages, we collected information such as embankment conditions, culvert conditions, ground conditions, and seismic motion conditions, and organized and analyzed the relationship with the amount of damage. From the results of macro analysis, “overburden”, “alluvial thickness”, and “earthquake ground motion SI value” were extracted as correlated parameters. From the results, we created a flow to select the points where countermeasures should be considered and a simple estimation formula for the maximum damage amount. This made it possible to determine the primary selection of whether or not countermeasures need to be examined and the priority of countermeasures with a certain degree of accuracy.