振動台大型剪力盒試驗砂土液化後沈陷量之研究
Date Issued
2004
Date
2004
Author(s)
程漢瑋
DOI
zh-TW
Abstract
During or after earthquake, the seismically induced excess pore water pressure in saturated sand layer would dissipate with time, and the volume of the sand layer decreases and settlement occurs. In this study, a biaxial laminar shear box on a shaking table at National Central Research of Earthquake Engineering (NCREE) was used to conduct the shaking tests of large-scale physics model. The dimension of the specimen is 1.88 m x 1.88 m x 1.52 m. The shear box is composed of 15 layers of inner and outer frames. For each layer, the frame motion (inner frame and outer frame) is independent from other layers. The soil sample deformed according to the shear waves induced from the shaking table motions.
In this study we used the saturated sand from Vietnam. So far, five series of shaking table tests has been performed. The input motions for the shaking table are uniform sinusoidal wave shaking with acceleration amplitudes from 0.03 g to 0.15 g, frequence of 1 Hz, 2 Hz, and 4 Hz and duration of 5 sec, 10 sec, and 20 sec. One dimensional and two dimensional shaking tests were carried out. The results from these tests showed there are settlements in the saturated sand, being liquefied or not, and the settlement tends to increase with shaking duration. Beside, the settlement in non-liquefied sand layer is much smaller than that in liquefied one. The settlement during liquefaction increases with the acceleration amplitude. For the same acceleration amplitude, the settlement in 2D shaking is larger than that in 1D shaking. It is observed that the volumetric strain of the liquefied sand layer relates to its relative density, but not to either the acceleration or the direction of vibration (1D or 2D shaking). In this study the maximum shear strain in the liquefied sand layer is between 0.5% and 3.5%, and the volumetric strain after liquefaction of the sand layer is similar to prior researches by others.
Subjects
振動台
液化
沈陷量
shaking table
liquefaction
settletment
Type
thesis