• Geomechanics and Engineering
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• v.8 no.5
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• pp.707-726
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• 2015

This paper investigates the time dependent behaviour of Haarajoki test embankment on soft structured clay deposit. Half of the embankment is constructed on an area improved with prefabricated vertical drains, while the other half is constructed on the natural deposit without any ground improvement. To analyse the PVD-improved subsoil, axisymmetric vertical drains were converted into equivalent plane strain conditions using three different approaches. The construction and consolidation of the embankment are analysed with the finite element method using a recently developed anisotropic model for time-dependent behaviour of soft clays. The constitutive model, namely ACM-S accounts for combined effects of plastic anisotropy, interparticle bonding and degradation of bonds and creep. For comparison, the problem is also analysed with isotropic Soft Soil Creep and Modified Cam Clay models. The results of the numerical analyses are compared with the field measurements. The results show that neglecting effects of anisotropy, destructuration and creep may lead to inaccurate predictions of soft clay response. Additionally, the numerical results show that the matching methods accurately predict the consolidation behaviour of the embankment on PVD improved soft clays and provide a useful tool for engineering practice.

• Korean Journal of Community Nutrition
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• v.17 no.1
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• pp.109-118
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• 2012

This study was conducted to characterize changes in the meal structure of Korean children in terms of temporal and spatial dimensions. The data of 1,891 and 1,627 school-aged children and adolescents extracted respectively from the 1998 and 2009 Korea National Health and Nutrition Examination Surveys were analyzed by gender, age group, and residential area. From 1998 to 2009, the total eating events increased from 4.3 to 4.6 (p = 0.001); the average number of meal intake decreased from 2.8 to 2.7 (p < 0.001) while that of snack intake increased from 1.5 to 1.9 (p < 0.001). The prevalence of "3 meals a day" pattern tended to decrease while that of "2 meals a day" pattern increased over the years. Especially, the "2 meals a day" pattern with "lunch + dinner" increased from 13% in 1998 to 20% in 2009. The percentage of eating breakfast or dinner at home decreased over the years. These results indicate that over the last decade, "destructuration" occurred in Korean children's meal structure in terms of temporal and spatial dimensions. Especially, such alteration was more distinctive in male than female and in the high school-aged group than the elementary or middle school-aged groups. Overall, the difference of meal structure between genders and residential areas became smaller while the difference among age groups became larger over the years.

• Geomechanics and Engineering
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• v.10 no.6
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• pp.827-836
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• 2016

The rate of softening is an important factor to determine whether the failure occurs along localized shear band or in a more diffused manner. In this paper, strength loss and softening rate effect depending on sensitivity are investigated for weakly cemented clays, for both artificially cemented high plasticity San Francisco Bay Mud and low plasticity Yolo Loam. Destructuration and softening behavior for weakly cemented sensitive clays are demonstrated and discussed through multiple vane shear tests. Artificial sensitive clays are prepared in the laboratory for physical modeling or constitutive modeling using a small amount of cement (2 to 5%) with controlled initial water content and curing period. Through test results, shear band thickness is theoretically computed and the rate of softening is represented as a newly introduced parameter, ${\omega}_{80%}$. Consequently, it is found that the softening rate increases with sensitivity for weakly cemented sensitive clays. Increased softening rate represents faster strength loss to residual state and faster minimizing of shear band thickness. Uncemented clay has very low softening rate to 80% strength drop. Also, it is found that higher brittleness index ($I_b$) relatively shows faster softening rate. The result would be beneficial to study of physical modeling for sensitive clays in that artificially constructed high sensitivity (up to $S_t=23$) clay exhibits faster strain softening, which results in localized shear band failure once it is remolded.