Hydrodynamic Pressure Generated in Irrigation Pipelines during Earthquakes

Abstract

Earthquake ground motion is known to generate hydrodynamic pressure in irrigation pipelines. However, there are a few recorded observations of this phenomenon, so such hydrodynamic pressure is not well understood. We made continuous observations of earthquake acceleration and hydraulic pressure at irrigation pipelines in operation, and measured hydrodynamic pressure during 17 earthquakes with seismic intensities ranging from 2 to 4 on Japanese scale. This study reports on analyses based on the data obtained. (1) The maximum velocity of earthquake ground motion and the maximum hydrodynamic pressure during the earthquake have a linear relationship whose correlation coefficient exceeds 0.9. (2) The hydrodynamic pressure increases as a result of overlaps in the hydrodynamic pressures generated at several locations along the pipeline. (3) The maximum hydrodynamic pressure during an earthquake can be estimated using a theoretical equation analytically derived from the basic formula for hydrodynamic pressure, assuming sine waves as the input earthquake ground motion.