Development of sensor for monitoring seismic liquefaction

Abstract

Recent studies have revealed that damage to gas pipelines buried underground is mainly caused by liquefaction of the surrounding soil mass. Therefore, if the occurrence of liquefaction in underground soil where gas pipelines are buried can be detected immediately after an earthquake, a more efficient and quick measure can be implemented to prevent the expansion of damage. With this in mind, a "liquefaction sensor" which is based on the measurement of water level within a hollow pipe inserted underground is developed, instead of the conventional pore water pressure meter which is less durable. Several experiments, ranging from laboratory boiling tests and shaking table experiments to field flow and vibration tests, were carried out to examine the adaptability of the sensor. From these tests, it was observed that the water level inside the pipe increases as the excess pore water pressure in the adjacent ground is increased, and the two variables have a nearly proportional relation to each other. Therefore, the occurrence of liquefaction can be detected by measuring the water level within the pipe of the liquefaction sensor.