1989 Fiscal Year Final Research Report Summary
Estimation method for pore water pressure under shearing deformation
| Project/Area Number |
62550364
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
基礎・土質工学
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| Research Institution | Hakodate National College of Technology |
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Principal Investigator |
SANO Yoshifusa Hakodate National College of Technology, Associate Professor, 土木工学科, 助教授 (90041897)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Triaxial Compression Test / Clay / Pore Water Pressure / Plastic Pore Water Pressure / Consolidated and Undrained Shear / vertical axial strain |
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| Research Abstract |
Many behaviors in subsoil can be explained by effective stress, but not by total stress. Effective stress is conceptual value, which is assumed to be acted on soil skeletons. The stress is not directly measured, but estimated in calculation of total stress minus pore pressure. In practical problems, total stress is easily estimated, while no ways for estimation of pore pressure under shear are established. Pore pressure induced in shear can be divided into elastic and plastic components. As plastic pore pressure is irrecoverable, it must be deeply concerned with axial strain. To clear it in experiments, some undrained triaxial test according with some sorts of total stress path have been carried out.Excess pore pressure heavily depends on total stress path, but using plastic pore pressure can weaken those effects. However, its accuracy is insufficient,and isotropy in a specimen is questionable.Elastic pore pressure is assumed to be equal to increase in mean principal stress.
Although triaxial test is called an element test, ends of a specimen are prevented from free deformation because of friction and restriction.On the other hand, center portion of the specimen is considered to be free from restriction. Therefore, pore pressure is to be unequal in a specimen,whereas pore pressure is generally measured at end of a specimen from the technical view point. So, resultant value is obtained of pore pressures at center and end. A miniature pore pressuremeter is put at midheight of a specimen to measure pore pressure at center. Two pore pressures at mid-height and at end are nearly equal in slow tests but not in quick tests. Even in slow tests,adequate pore pressure in shear zone is not obtained if the meter is outside from failure zone in case with distinct shear failure. Specimens must be in uniform deformation as element tests.
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Research Products
(10 results)
