COOPERATIVE RESEARCH ON THE PREDICTION METHODS AND EVALUATION OF DEFORMATION OF EARTHSTRUCTURES FOUNDED ON SOFT FOUNDATIONS DURING EARTHQUAKES

点击翻译按钮获取中文摘要

Case histories and studies of damages caused by ground deformation due to recently hit earthquakes, e.g. Sanriku Haruka-Oki Earthquake, Kushiro-Oki Earthquake and Hyogo-Ken Nanbu Earthquake, are first made in this study. Laboratory tests, such as triaxial compression apparatus, hollow cylinder appartus and ring shear apparatus, are conducted to investigate deformation behavior of sandy soils. It is reported that each type of earth structures possesses a specific mechanism governing the ground deformation, and it is desirable to deduct an appropriate mechanism involved in each case study for analyzing it. Especially, triaxial compression test results on soils containing large grains sampled from the Kobe Port Island which experienced extensive liquefaction are reported. As a result of this study, it is found that deformation characteristics of soils depend on the depositional structures and the pore water pressure suddenly rises upon unloading immediately after the shear strain exceeds 5 %. Shaking table tests are carried out to examine countermeasures against floatation of buried pipes in liqiefied ground and deformation of surrounding ground. it is found that the amount of the pipe floatation depends heavily on the movement of the surrounding soil, and the countermeasures against such soil movement is devised and experimentally verified. A deformation analysis method on lateral ground flow is proposed, based on the energy principle. It is capable of coping with a variety of boundary conditions. In this study, it is applied to solve the deformation mechanism occuring at the river dikes protected by sheet piles subject to earthfill weight. As a result of this study, this analytical method is verified for the ground flow involving a large area.