Volumetric Strain of Large Specimen in Shaking Table Test
Date Issued
2005
Date
2005
Author(s)
Wu, Ji-Wei
DOI
zh-TW
Abstract
Volumetric Strain of Large Specimen in Shaking Table Test
ABSTRACT
The shaking due to earthquakes or vibrations will generate excess pore water pressure in saturated sand. After shaking, the excess pore water pressure in the saturated sand layer dissipates with time, and the volume of the sand layer decreases and settlement occurs. In 1999, Chi-Chi Earthquake caused liquefaction in many areas with sandy soil layer in mid-Taiwan, for example, Taichung Seaport, Yuanlin, Wufeng and Nantou area. This experience alarms us that there is necessity to study further the liquefaction problem of sandy soil in Taiwan. 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 a large-scale physics model. The dimension of the specimen is 1.88 m × 1.88 m × 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.
Ueng et al.（2002）used the saturated sand from Vietnam. So far, eight series of shaking table tests has been performed. The test results showed that if liquefaction did not occur, there is no obvious relation between the average volumetric strain of the sand and the acceleration of vibration, frequency of vibration, duration of vibration, or mode of vibration. When liquefaction occurred, for the same duration of vibration, volumetric strain is only related to relative density, but not acceleration of vibration, frequency of vibration or direction of vibration. Volumetric strain decreases with increase of relative density, and increases with increasing shaking duration. These relations can help us to calculate the quantity of settlement due to liquefaction. This research has been verified by the shaking tests with the recorded earthquake motions and the field settlement data.
Key words: liquefaction,laminar box,shaking table,settlement,volumetric
strain,sand,earthquake.
Subjects
液化、大型剪力盒
振動台
體積應變
沉陷
地震
砂
liquefaction
laminar box
shaking table
settlement
Type
thesis
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