• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.127-135
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• 2002

The accurate evaluation of settlement is important to every steps in the constructions involving soft soils. Relating with those constructions, especially, it has been emphasized recently that the influnce of secondary settlement is important. The ratio of $C_a/C_c$ and the surcharging tests can be applied collaboratively to predicting and reducing secondary consolidation. A series of incremental loading consolidation test and surcharging tests for undisturbed samples of Kunsan clay were performed in this study. As a result of the tests, the ratio of $C_a/C_c$ for the clay was found to be 0.0329. Also, the relationship between void ratio and $t/t_p$ was shown to be linear. Accordingly, the secondary compression index, $C_a for a long term loading had a constant value regardless of time. When the total surcharge ratio was 0.4 and the dissipation ratio of excessive porewater pressure was in the range from 80% to 100%, secondary settlement was effectively reduced for Kunsan clay.

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.617-625
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• 2001

Peace dam constructed against the water attack had stopped in the first step, linked with Hwacheon dam through bypass tunnels and had an effect of flood surcharging in its pocket on Hwacheon dam downstream. To study the utility of Peace dam, the flood control effects of Peace dam and the restricted water level (RWL) in Hwacheon dam were reviewed and identified with operating Hwacheon dam system. Analysing the results the ideas of expanding the usability of the water resources in Hwacheon dam system were suggested. To do that, the criteria and the model of reservoir operation were established frist and the optimization of the operation have done. Based on the results the performance of the optimization was evaluated as an reference coefficient with relative value of the registered data to the optimized. And examining several alternatives for the RWL in Hwacheon reservoir operation made more feasible RWL suggested. And its economic benefit was also reckoned.

• Journal of the Korean GEO-environmental Society
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• v.7 no.3
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• pp.5-19
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• 2006

The secondary consolidation settlement of soft clay is generally very little compared to the total settlement and occurs very slowly during long-term period. However the secondary consolidation settlement is comparatively large amount in organic and heavily compressed clay and is a very important engineering factor. In order to reduce residual settlements in reclaimed soft ground, the preloading method is often used. In this study, in order to determine reasonable long-term settlements of large reclaimed site, laboratory incremental loading consolidation tests and surcharging consolidation tests are performed. Sampling was done at Incheon area of west coast and Gwangyang area of south coast in Korea. The characteristics of secondary consolidation have obtained through laboratory tests and analyzed systematically to predict long-term settlements. Additionally, the location data and laboratory test results are correlated by using GIS(geographic information system). The secondary consolidation settlement of the site was predicted based on D/B and the operation technique and estimation technique of space of GIS.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.257-258
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• 2005

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.940-950
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• 2010

In case of uneven surcharge like backfill or embankment after constructing caisson applied on the deep soft marine deposits, lateral deformation of soft soils would happen due to plastic deformation of soil particles by increase of excess pore water pressure. Lateral deformation of soil will result in the caisson displacement which affects soft soil-caisson structure safety. Soft soil was improved by soil compaction pile method, and then gravity caisson was installed. Soil deformations were monitored and analyzed with step by step backfill and embankment behind the caisson. Amount and speed of lateral deformation after the installation of caissons were closely related with the time of backfill and embankment. The relationship between maximum lateral displacement($\Delta_y$) in front of caisson and settlement($\Delta_s$) can be expressed as $\Delta_y=(0.0871)\Delta_s+122.95$. Soft soil depth did not affect the lateral displacement of caisson in this study, which can be explained the soft soil improvement under the caisson by S.C.P. method. Substantially the amount and speed of the lateral deformation of caisson were closely related with the uneven surcharging rate behind caisson.

• Geomechanics and Engineering
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• v.7 no.3
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• pp.279-295
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• 2014

A series of one-dimensional consolidation tests and triaxial creep tests were performed on Nansha clays, which are interactive marine and terrestrial deposits, to investigate their time-dependent behaviour. Based on experimental observations of oedometer tests, normally consolidated soils exhibit larger secondary compression than overconsolidated soils; the secondary consolidation coefficient ($C_{\alpha}$) generally gets the maximum value as load approaches the preconsolidation pressure. The postsurcharge secondary consolidation coefficient ($C_{\alpha}$') is significantly less than $C_{\alpha}$. The observed secondary compression behaviour is consistent with the $C_{\alpha}/C_c$ concept, regardless of surcharging. The $C_{\alpha}/C_c$ ratio is a constant that is applicable to the recompression and compression ranges. Compared with the stage-loading test, the single-loading oedometer test can evaluate the entire process of secondary compression; $C_{\alpha}$ varies significantly with time and is larger than the $C_{\alpha}$ obtained from the stage-loading test. Based on experimental observations of triaxial creep tests, the creep for the drained state differs from the creep for the undrained state. The behaviour can be predicted by a characteristic relationship among axial strain rate, deviator stress level and time.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.442-451
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• 2008

The evaluation of field degree of consolidation on soft clays has been an important problem in geotechnical areas. Monitoring either settlements or pore water pressures has been widely applied in the filed, but occasionally they have some problems. This study addresses the suggestion and application of another method for evaluating the degree of consolidation using shear wave velocities. A research site where soft clay layers were consolidated by surcharging loads was chosen. Laboratory tests were performed to determine the relation between shear wave velocity and effective stress. Field seismic tests were conducted several times during the consolidation of the clay layers. The tests results show that the shear wave velocity increased significantly as clays consolidated. The shear wave velocities at each field stress states were derived from the laboratory results and the degree of consolidation was evaluated by comparing the shear wave velocities obtained by laboratory and field seismic methods. In most stress states, the degree of consolidation evaluated using the shear wave velocity matched well with that obtained from field settlement record, showing the potential of applying the method using shear waves in the evaluation of field degree of consolidation on soft clay deposits.

• Journal of the Korean Institute of Rural Architecture
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• v.2 no.2
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• pp.115-126
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• 2000

Retaining walls are used to prevent excessive movement of retained soils. Typical retaining walls include gravity, reinforced concrete, reinforced earth and tie-back. However, from a practical viewpoint there are still drawbacks among these often constructed retaining walls. New types of retaining walls constructed with precast concrete blocks are proposed. This type of retaining wall is incorporates each blocks interconnected with adjacent block by connecting unit to build up a flexible retaining-wall system. This paper focus to behavior characteristics includes deformation and distribution of lateral earth pressure by loading tests and FEM analysis. For model tests, a 1/10 scale reduce models are manufactured include unevenness part, drainage hole and connecting unit and steel wire used to connect each blocks with adjacent block. To simulate the real retaining walls closely, uneven parts are interconnected each other and the construction type of blocks and wall front inclination are varied to investigate the relative displacement of individual block and the location of maximum deformation of wall as increasing surcharging. Additionally, PENTAGON3D, which solve the geotechnical and other problem, used for verifying and comparing with model tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.854-862
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• 2018

The Government R&D budget for 2019 exceeded 20 trillion won in order to develop future growth market such as basic research investment and creation of growth engine. As such, the importance of R&D investment is increasing, and various schemes for enforcing efficient and transparent business expenses are being expanded. However, research expenses (Charge ratio) such as fraudulent execution of funds are continuously being generated, and a system of imposition of sanctions is being introduced. In this paper, the legal grounds of sanctions, comparative review of laws and regulations between the ministries, and the criteria of imposition (imputation) were analyzed. In addition, since the amendment of the standard for imposing the intergovernmental surcharges, a single standard has been applied, and the transition process of the surcharging system has been reviewed. As a result of the data analysis, it was found that they focused on micro - utility activities and suggested new policy measures corresponding to them. The Korea Academia-Industrial cooperation Society. The Korea Academia-Industrial cooperation Society.