Analysis of Soil Liquefaction: Niigata Earthquake

During the Niigata earthquake of June 16, 1964, extensive damage to engineering structures occurred as a result of liquefaction of the sandy soil on which they were supported. The results of field investigations conducted by Japanese engineers are presented, leading to conclusions concerning the variation of relative density of the sand with depth in regions where liquefaction did and did not occur. An analysis is then proposed, using computations of the time-history of shear stresses likely to be generated in the sand by the earthquake ground motions and the results of cyclic shear tests on saturated samples of sand, which provides results in good agreement with the observed field behavior. The analysis is also used to assess the effects of minor changes in intensity of ground shaking or depth of water table and the provision of surcharge fills on the possibility of soil liquefaction at Niigata. The good agreement between the predicted and observed behavior suggests that the method of analysis might be useful for evaluating the possibility of soil liquefaction in other areas.