Pore Water Pressure Generation with High Fines Content Specimens in Dynamic Triaxial Tests
Date Issued
2005
Date
2005
Author(s)
Yeh, Chun-Lin
DOI
zh-TW
Abstract
Pore Water Pressure Generation with High Fines Content Specimens in Dynamic Triaxial Tests
Abstract
In the typical CKC cyclic triaxial tests, the researchers often use small and stiff tubes to connect the cap and bottom of the specimens to the pore water pressure sensors. They assume that there is no change in the volume of specimens and measure systems in undrained tests.
In fact, the volume change exists in the triaxial measurement systems when water pressure changes. Therefore, when the pore water pressure changes in certain location of the sample, the soil in other location or at another end of the water pressure measurement of the pipeline can experience the pressure change only when water flow occurs. Flowing can occur and reflect the pore water pressure change rapidly for sand of high permeability, but there is lower permeability in the sand of a high fines content. The pore water pressure measurement cannot reflect the pore water pressure changes within the specimen immediately.
This research pointed out the major factors of pore water pressure measurements for high fines content soil in dynamic triaxial tests as follow:
(1)Permeability: There are different permeabilities for soils of different fines contents. The higher fines content the lower permeability of the soil, so it cannot reflect true pore water pressure situation within specimen immediately in the pore water pressure measurements.
(2)Frequency of cyclic loading: There is a longer duration of loading during tests of lower frequency, and pore water pressure measurement can obtain better pore water pressure within the samples.
(3)Cyclic stress ratio, CSR: Higher pore water pressure changes usually occur in the triaxial tests with larger CSR, and result in more volume change in the pipeline section.
Subjects
砂
細粒料含量
液化
三軸動力試驗
孔隙水壓
反覆剪應力比
sand
fine content
liquefaction
dynamic triaxial test
pore water pressure
cyclic stress ratio
Type
thesis
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