• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.10a
• /
• pp.103-108
• /
• 1999

This paper describes development of a new automated real-time system which preforms measurement data reduction and management, geotechnical backanalysis, and feedback design for embankment construction on soft ground. Such a system can be an effective, useful and economical tool for managing a large site development on soft ground. The system consists of data base system to characterize soil properties and identify instrumentation, analysis system for ground behavior and stability coupled with automatic monitoring system, and feedback design system which is a new technique to reflect the analysis of measured ground behavior against original design.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.309-316
• /
• 2000

When highly compressible, clayey soil layers lies at a limited depth and large consolidtion settlements are expected as the result of construction, precompression of soil may be used to minimize postconstruction settlement. In this study, we tried to find the possibility about the effect of ground improvement using flat dilatometer at the Inchon International Airport where preloading was installed. Field and laboratory tests were performed for soft ground before and after preloading in order to check the effectiveness of the soft ground improvement and compared with the test results of dilatometer which obtained before and after preloading at the same location Field tests such as flat dilatometer, vane, CPTu tests were performed before and after preloading and undisturbed samples are obtained to carry out laboratory tests. As comparing results, after preloading, unit weight, effective stress, undrained shear strength were increased and we can also check the decrease of consolidation late caused of decrease of void ratio. Furthermore, it is assumed that the possibility on the effect of ground improvement by using the flat dilatometer

• Journal of the Korean Geotechnical Society
• /
• v.28 no.8
• /
• pp.89-99
• /
• 2012

The expansion of a road on soft ground could induce an additional settlement to the existing road because of the consolidation characteristics of the soft soil layer subjected to additional load by an adjacent banking. In such case, the existing road could be faced with various problems during the stages of the construction and maintenance, such as deterioration of not only the surface smoothness yielding the decrease in automobile performance safety but also the structural stability of the embankment. These kinds of problems are expected to occur more freguently especially for the deep ground level with a fairly thick soft soil layer. Therefore, they should be examined and studied adequately during the design stage. As a reference case study, this paper deals with the project named Namhae Expressway of 2nd Branch with the soft soil layer with the thickness upto about 50m. After a lengthy review of the original design, an improved design is proposed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.701-708
• /
• 2003

Recently, piezocone penetration test is frequently conformed in order to estimate the characteristics of soft ground with standard penetration test, generally used in the past. The soil characteristics, such as cone penetration resistance, friction resistence and excessive pore water pressure, can be evaluated continuously through the piezocone penetration test. In Incheon International Airport 2nd phase site preparation, standard penetration test and piezocone penetration test were used in order to increase the confidence for determination of soft ground depth. And the compressible layer was determined by the comparison between the preconsolidation pressure and the designed increase pressure. As the results, the relation between standard penetration test and piezocone penetration test shows q$_{c}$=(1.09~l.63)N at the soft ground, determined by 5/30 N value. And q$_{c}$=(1.21~l.98)N was shown at the point of compressible layer, evaluated by the preconsolidation pressure. These results were applied to determination for the depth of soft ground and to design the improvement for the soft clay.lay.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.17-24
• /
• 2000

Hardening agent has been the traditional material for surface soil stabilization of soft ground. This study aims at determining optimal mixture ratio of hardening agent in accordance with the required design specifications. Hardening agent is properly mixtured with Fly ash, Gypsum, Slag and Cement for the ettringite hydrates which is effective for early stabilization of unconsolidated soil. The treated soil is the clay which are widely found here and there in Korea. In this study, preliminary tests were performed to get optimal mixture ratio of stabilizer ingredient, and marine clay in Jin-Hae was used to get physical and chemical properties. Laboratory tests of 50 stabilized soil were peformed to get optimal mixture ratio for 16 stabilizer material of 6 type, and stabilizer mixing was determined.

• Journal of the Korean Professional Engineers Association
• /
• v.44 no.6
• /
• pp.45-50
• /
• 2011

As the Deep Cement Mixing Method is composed of drilled natural soft soil structure and injected cement slurry to be mix together in it, the nature of excavated ground is influenced directly to the application of constructability. Also the nature of in situ soil is the main material, the mix design and construction work plan should be established before the investigation of soil which is performed through the whole site confirm the soil parameter before construction. The nature of investigated soil and water level as should be performed accurately.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.475-483
• /
• 2008

It is necessary to develop a national design method for surface reinforcement of very soft ground because most current design works rely on crude empirical correlations. In this paper, the mechanical behavior of very soft ground that is surficially reinforced was investigated with the aid of a sents of numerical analysis. Several material properties of each dredged soft ground, reinforcement and backfill sand mat have been exercised the numerical analysis in order to compare the result of numerical analysis with those of the laboratory model test. Through the matching process between the numerical and experimental result, it is possible to find the appropriate material properties of the dredged soft ground, reinforcements and backfill sand mat. These verified material properties permit to show the effect of the stiffness of reinforcement and the thickness of sand mat on the overall deformation.

• Journal of Ocean Engineering and Technology
• /
• v.20 no.5 s.72
• /
• pp.49-56
• /
• 2006

In this thesis, centrifuge model experiments and numerical analyses were carried out to investigate the behavior of an excavated slope in soft clay ground. Centrifuge model tests were performed with various slopes for the excavated ground, such as 1:1.5 and 1:2. Pore pressuresthe model ground were measured to find their effects on the stability of the excavated slope. These experiments showed that the model with 1:2.5 maintained its stability within a short period of time and failed gradually. Therefore, anexcavated slope of soft soil with this slope might maintain stable conditions within a certain time. The mode1 with a 1:3 slope was observed to maintain a very stable condition, showing insignificant deformation in the ground after being excavated. Numerical analyses with PLAXIS, a commerciallyavailable software implemented with the finite element numerical technique, were performed to find the pore pressure distribution within the ground mass and the deformation of the soil. From the results of numerical analysis, a negative pore pressure was developed after the excavation and thus the stability of the slope was maintained. The safety factor for slope failure was found to decrease with time because of the dissipation of negative pore pressure with time.

• Journal of Industrial Technology
• /
• v.11
• /
• pp.65-72
• /
• 1991

In this paper, a control algorithm is discussed when the quadruped walking robot walks over the unknown soft ground. Firstly, it estimated the relationship between the foot force and the ground sinkage at the leg-placing phase. Secondly, the generated soil property is applied to the leg-supporting phase. If the attitude angle is changed by incorrect ground sinkage compensation, the control algorithm adjusts the attitude angle using simplified orientation orientation matrix.

• Geomechanics and Engineering
• /
• v.6 no.5
• /
• pp.419-436
• /
• 2014

Soil improvement by preloading with PVD in combination with vacuum is helpful when a considerable load is required to meet the desired rate of settlement in a relative short time. To facilitate the vacuum propagation, vertical drains are usually employed in conjunction. This ground improvement method is more and more applied in the Mekong delta of Vietnam to meet the needs of fast infrastructure development. This paper reports on a pilot test that was carried out to investigate the effect of ground improvement by vacuum and PVD on the rate of consolidation at the site of Saigon International Terminals Vietnam (SITV) in Ba Ria-Vung Tau Province, Viet Nam. Three main aspects of the test will be presented, and namely, instrumentation and field monitoring program, calculation of consolidation settlement and back-analysis of soil properties to see the difference before and after ground improvement.