• Journal of the Korean Geotechnical Society
• /
• v.22 no.9
• /
• pp.5-14
• /
• 2006

Generally, the sediments contain significant water, clay, colloidal fraction and contaminants, and can result in soft strata with high initial void, and its potential hazards in subsurface environments exist. Electrokinetic technique has been used in sedimentation for volume reduction of slurry tailing wastes and in remediation for extraction of contaminants from contaminated soils. In this research, the coupled effects of sedimentation and remediation of contaminated sediments are focused using electrokinetic sedimentation and remediation techniques from experimental aspects. A series of laboratory experiments including variable conditions such as initial solid content of the specimen, concentration level of the contaminant, and magnitude of applied voltage are performed with the contaminated sediment specimens mixed with ethylene glycol. Commercially available high specification Kaolin was used to simulate slurried sediment. From the test results, the settlement of specimen increases with increasing of applied voltage and decreasing of solid content and contamination level. The density of specimen increases due to settlement of specimen in the process of electrokinetic sedimentation and decreases due to extraction of organic contaminant in the process of electrokinetic remediation.

• Journal of the Korean Geosynthetics Society
• /
• v.21 no.1
• /
• pp.11-21
• /
• 2022

In this study, the individual vacuum seepage consolidation method, a new soft ground improvement method, was developed to supplement the conventional suction drain method (individual vacuum preloading method) and the geotechnical behavior was predicted through numerical analysis. If the individual vacuum seepage consolidation method applied, the effect of accelerating settlement and increasing the amount of settlement was high when the aquifer was located in the middle or at the bottom of the layer to the target improvement layer. It was found that the pumping amount in the aquifer does not affect the settlement behavior when it exceeds a certain level. Even vacuum pumping wells were installed in various locations, such as inside or outside of the embankment, the difference in settlement and horizontal displacement was insignificant. In addition, it was predicted that the settlement rate was the fastest and the horizontal displacement (inward) was large when both methods were carried out at the same time. Since this method can reach the target settlement amount very quickly, it was confirmed that it is possible to increase the spacing of vertical drain, thereby securing economic feasibility.

• Journal of the Korean Geosynthetics Society
• /
• v.9 no.2
• /
• pp.1-9
• /
• 2010

At present, the sand mat method is actively used for improvement of soft ground. But, there are some problems related with sand mat which has been used as a way to accelerate consolidation settlement. First of all, insufficiency of sand due to imbalances in market supply and demand is the one of the biggest problems, which makes price high of sand and delays a term of total construction work. Moreover, it is necessary to preserve integrity of environment from natural disruption caused by indiscreet quarrying and dredging operation to supply sand for soil improvement construction site. This paper presents the feasibility study to use of Precious Slag Ball instead of sand mat as the replacing material through the basic soil property tests, the medium of discharge capacity test and analysis of settlement property. It is also evaluates the performance of Precious Slag Ball as a sand mat in terms of discharge capacity, ground settlement by the K-Embank program based on field experimental work.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.5
• /
• pp.17-24
• /
• 2020

In order to analyze the effect of applying the bioreactor landfills on the waste landfill for acceleration of waste biocompression, a settlement experiment was performed. The secondary compression indices (C_α) were analyzed, and compared with the results of experimental studies conducted in other countries. Analyses of C_α from the experiment showed that the recirculation method of mixing leachate and FWL could accelerate the waste settlement as much as 2.9 times and 2 times more than the leachate recirculation and the sanitary landfills due to additional biocompression generated by the organic matter in FWL. The C_α in this study was smaller than the C_α of the other studies due to the low organic content of the waste in accordance with domestic waste policies to reduce food waste. The relation between biodegradable waste content and C_α was analyzed. The C_α of the waste was shown to be sensitive to biodegradable waste content, and become higher as the content of the biodegradable waste increases.

• Geotechnical Engineering
• /
• v.1 no.2
• /
• pp.27-40
• /
• 1985

This study aims at the development of computer Program for the deformation analysis of soft clay layers, and using this computer program, study the constraint effect of deformation- heaving, lateral displacement-of the soft clay layers reinforced with sheet pile at the tip of banking or improvement of soft clay layer up to hard strata, under intact state (natural) and the state of vertical drain respectively. For this study, Biot's consolidation theories and modified Cam-clay theory for constitutive equation for FEMI were selected and coupled governing equation, and christian-Boehmer's technique was applied to solve the coupled relationship. The following results are obtained. 1. Sheet pile or improvement of soft clay layer to the hard strata work well against the settlement of neighboring ground. B. In view of restriction of heaving or lateral displacement, sheet pile is not supposed to be of use. 3. Sheet pile is of effect only when vertical drain is constructed for acceleration of consolidation and load increases gradually. B. The larger the rigidity of improvement of layer to hard strata is, the less settlement occurs.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.4
• /
• pp.147-158
• /
• 2015

In this study, sewer backfill material was developed to prevent sewer damage and ground subsidence. Laboratory test was performed in the field of CA replacement ratio, accelerator type and replacement ratio and W/M. The compression strength of backfill material was 0.55~0.64MPa below in W/M 70% and 0.20MPa over W/B 80%. Ice block was used to simulate the ground cavity and subsidence caused by sewer damage in application study. The existing sand compaction and the new backfill material was comparative estimated in field. The ground settlement of cross section was 23.4cm and that of longitudinal section was 27cm in sand compaction section, but the ground had not sunk in backfill material section.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.6C
• /
• pp.287-294
• /
• 2009

Suction Drain Method is a relatively new technique to improve soft ground using vacuum pressure which can be directly applied to the soft ground through drains that the pore water pressure around them are decreased without changing total stress. This can accelerate volume changes and increase strength of the ground. This paper shows the results of field test of the suction drain method applied at dredged and reclaimed clay. To evaluate the improvement effects of soft ground by the suction drain method, this paper analyzed real-time field measurements to the results of the laboratory tests and numerical analysis. The comparisons of the settlement and shear strength between suction drain method and surcharge preloading method show possibilities for replacement of the preloading methods. The settlements by suction drain method were 2.3 times larger and undrained shear strength were 300%~400% higher than surcharge method. Moreover, the water content is decreased about 30% and the preconsolidation pressure is increased about $0.52kgf/cm^2$.

• Land and Housing Review
• /
• v.2 no.2
• /
• pp.163-170
• /
• 2011

Individual Vacuum Pressure Method (IVPM) is a soft ground improvement technique, in which a vacuum pressure can be directly applied to the vertical drain board to promote consolidation and to strengthen the soft ground. This method does not require surcharge loads, different to embankment or pre-loading method. In this study, the ground improvement efficiency of Individual Vacuum Pressure Method was estimated when suction pressure increases step by step(-20, -40, -60, -80kPa) with different periods. During Individual Vacuum Pressure Method process, surface settlement and pore pressure were monitored, and cone resistance as well as water content were also measured after the completion of Individual Vacuum Pressure Method treatment. From the results, optimum duration of each step of vacuum pressure was determined, and the settlement was calculated using FEM numerical analysis.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.5
• /
• pp.13-24
• /
• 2012

In this study, the in-situ model test has been conducted and used to estimate and analyze consolidation behavior of the ground by using the miniature test that reconstructs economically geotechnical behavior of in-situ full scale structure. To analogize the relation among effective stress, void ratio and coefficient of permeability at the self-weight consolidation stage, the low stress seepage consolidation test has been conducted and the involution function of constitutive equation had been obtained from the result of the curve fitted seepage consolidation test result. As a result of the numerical analysis that had been conducted on the representative section using a constitute equation, final settlement was similar with those of self-weight consolidation of the centrifugal model test. But, it was more or less smaller. It seems that these trends are caused by the difference between estimated values.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.12
• /
• pp.37-45
• /
• 2009

Dredging and reclamation which have been conducted steadily for creation of new coastal area have the demerit of taking a long time. Hence, a lot of researches on acceleration of self-weight consolidation have been proceeding continuously. In this paper, 30 cases of laboratory self-weight consolidation tests were conducted to understand the application of PDF method, one of the self-weight consolidation acceleration methods, to domestic dredged soils. Acceleration effect of self-weight consolidation was confirmed through comparison and analysis of completion times and settlements of self-weight consolidation for none installed case and 4 kinds of common used PBD installed cases. As a result of the tests, installation of PBD before filling is effective for time reduction of self-weight consolidation.