| Co-Investigator(Kenkyū-buntansha) |
西山 竜朗 岡山大学, 大学院・自然科学研究科, 助手 (30294440)
MURAKAMI Akira Okayama University, Graduate School Science and Technology, Professor, 大学院・自然科学研究科, 教授 (80157742)
NISHIMURA Shin-ichi Okayama University, Graduate School Science and Technology, Graduate School Associate Professor (30198501)
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| Research Abstract |
Anisotropy generally exists in the permeability of natural clay deposits. It is an important factor for the consolidation behavior of soft grounds that are improved by vertical drains. In this research, the anisotropy of permeability was considered. Two types of consolidation tests, namely, vertical drainage and radial drainage tests, were conducted. Then, the coefficients of consolidation for the horizontal and the vertical directions were compared. Several kinds of remolded and undisturbed clays were tested. In the consolidation tests under different drainage conditions, the required time far the primary consolidation was different in each test. A comparison of the consolidation parameters in the two tests was difficult, since the effect of the secondary consolidation was different in each test. The inverse analysis method was applied to identify the consolidation parameters considering the secondary. consolidation. According to the test results, the difference between the vertical a
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nd the horizontal coefficients of consolidation was obtained more clearly with the proposed method than with the conventional t^n method. In conclusion, the difference was not so great, since the consolidation of the horizontal coefficients was 1-2 times that of the vertical ones.
Finally, the in-situ observation data, settlement and pore pressure in an actual soft ground were analyzed using the proposed inverse analysis method. The horizontal coefficients of consolidation identified from the in-situ observation data were compared wish the vertical coefficients determined from test results of undisturbed soil samples.
Soil parameters have great variability and the modeling of such statistical characteristics is often necessary for several kinds of analyses. In this study, a consolidation analysis is carried out considering the spatial variability of parameters, the coefficients of volume compressibility m_v and permeability k. The consolidation parameters are not constant throughout the consolidation process, and the non-Linearity is an important factor in soil behavior. The stochastic nonlinear consolidation model (SNCM), in which both factors, spatial variability and non-linearity are simultaneously considered, was proposed. According to the analytical results, the obtained prediction from relatively short observation period was satisfactory for the settlement and the pore water pressure behavior. In the identification results, the prior information gained through conducted soil tests was maintained relatively well for the coefficient of volume compressibility m_v, while the coefficient of permeability k was improved greatly. Less
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