Study on the substantial increase in the seismic stability of reinforced soil structures by preloading and prestressing

点击翻译按钮获取中文摘要

The basic mechanism of substantial increasing the seismic stability of reinforced soil structures by preloading and prestressing was studied by performing static cyclic loading tests and shaking table tests on small-scaled models of pier structures. Based on the proposal of the researchers, a prototype bridge pier for a railway bridge of geotextile-reinforced gravel has already been constructed near the Hakata station in Kyushu three years ago. The gravel backfill of the structure that was reinforced with a number of horizontal geotextile layers was preloaded in the vertical direction before having been fixed to prestressed conditions. The model test results showed that reinforced structures become very strong under seismic loading conditions as far as a sufficiently large prestress was maintained. When the input seismic load was a long period of uniform sinusoidal waves with an amplitude of 700 gals at a frequency that was nearly the same with the natural frequency of the structure, the nearly-resonance response at the top of the structure was as high as 2,000 gals. Even in that case, the structure exhibited only a limited amount of cyclic lateral displacement with some residual vertical compression. A method for maintaining prestress when the structure is exhibiting settlement was examined and found effective and practical. Geotechnical analysis of the test results was made for developing the design method.