1996 年 38 巻 4 号 p. 269-278
When ground-water is seasonally pumped up for the purposes of melting the snow on roads or of irrigation, the land subsidence of soft ground is caused by the periodical variation in ground-water level, even though the average level is almost constant. This paper introduces the land subsidence in Saga plain and Muikamachi of Niigata, where groud-water levels go down in summer or winter periodically. The investigation of observed data in both districts indicates that the subsidence is mainly caused by excess withdrawal of the ground-water. The subsidence is considered as cyclic one-dimensional consolidation with a large piriod of one cycle per year. A cyclic consolidation model is proposed to predict the settlement of ground caused by the seasonal variation in ground-water level. The analytical settlement of ground, including both settlements of the soft Ariake clay layer and the thick sand/gravel layer depositing until 84m in depth, shows a good agreement with observed value in Saga plain during 1976-1996. An analytical investigation is also performed to clarify the effects of pattern of ground-water level variations on land subsidence.