2007 Fiscal Year Final Research Report Summary
FUNDAMENTAL STUDY ON THE MITIGATION OF LIQUEFACTION INDUCED DISASTER BY INJECTING AIR BUBLLES IN THE GROUND
| Project/Area Number |
18560490
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geotechnical engineering
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| Research Institution | Chiba Institute of Technology |
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Principal Investigator |
HATANAKA Munenori Chiba Institute of Technology, FACULTY OF ENGINEERING, PROFESSOR (60333019)
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| Project Period (FY) |
2006 – 2007
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| Keywords | sandy soils / countermeasure to liquefaction / degree of saturation / relative density / P-wave velocity / liquefaction strength / roundness / air bublle |
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| Research Abstract |
A series of laboratory tests were performed in order to investigate the effects of the size and the roundness of soil particles, relative density, and air bubbles involved in the pore water of sandy soils on the relationship between the degree of saturation (Sr) and the P-wave velocity (V_p). The effect of degree of saturation on the liquefaction strength of sand was studied both on the undisturbed and reconstituted samples. The methods to generate air bubble and to insert the air bubble into the ground were also studied using model sand ground.
Following were concluded : (1) Unlike the effect of the size of soil particles of sand on the B-value-V_p relationship, its effect on the Sr-V_p relationship is small. The P-wave velocity increases rapidly with increasing degree of saturation from 90 % to 100 % for all sands tested ; (2) The effects of relative density on the Sr-V_p relationship are negligible ; (3) The effects of air bubbles involved in pore water both on B-value-V_p relationship and Sr-V_p relationship are significant ; (4) By comparing the liquefaction strengths obtained in the undrained cyclic triaxial tests on Futtsu sand, the method to decrease the degree of saturation by injecting the air bubbles into the sandy ground is expected to be a useful method to decrease the disasters induced by the sand liquefaction. (5) A simple method to unsaturate sand ground was successfully performed based on model ground test by inserting air bubble dissolved water into the ground under some water head.
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Research Products
(14 results)
