• Journal of the Korean GEO-environmental Society
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• v.13 no.8
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• pp.85-94
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• 2012

Evaluation of the smear effect caused by mandrel penetration into soft ground for a vertical drain installation is very important to predict the consolidation time of soft ground improvement. 30 kinds of laboratory model tests considering in situ conditions were conducted to investigate the formation of a smear zone and the decrease of coefficient of permeability in the disturbed zone. Three types(C(clay):M(silt)=1:1, 0.5:0.5, and 0:1) of reconstituted samples were used for 3 dimensional smear zone test. An experimental study was performed focusing on length of mandrel penetration, mandrel shape and size, earth pressure, and ground condition(unit weight and grain size distributions). Laboratory test results show that the length of mandrel penetration is the most critical factor for the formation of smear zone. As a result, the ratio between diameter of the smear zone($d_s$) and that of mandrel($d_m$) at field using long mandrel becomes larger than conventional $d_s/d_m$. The ratio between $d_s$ and $d_m$ ranges from 1.89 and 2.48 with the sample at C:M=1:0. It was also found that the $d_s/d_m$ value with the round shape of the mandrel is smaller than that of diamond one. The value of $d_s/d_m$ decreased with larger mandrel size, lower unit weight, and higher earth pressure. However, higher silt content led to increase of $d_s/d_m$. The ratio between coefficient of horizontal permeability in the smear zone($k_{hs}$) and that of undisturbed zone($k_{ho}$) ranged from 0.70 to 0.85. The test results imply that factors and values affecting $k_{hs}/k_{ho}$ show similar tendency with $d_s/d_m$.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.47-61
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• 2010

To predict the settlement rate of a ground area that incorporates vertical drains, it is desirable to conduct various kinds of advanced field and laboratory tests for hydraulic properties. However, it is urgently needed to appropriately evaluate the hydraulic properties using the results of conventional soil tests which are extensively used for local practice. To achieve this purpose, a number of CPT dissipation test, laboratory permeability and consolidation tests were performed at five sites in the floodplain of the Nakdong River delta, and the test data were comprehensively analyzed. As a result, it is found that the coefficients of horizontal consolidation ($C_{h,NC}$) and permeability ($k_{h,OC}$) of the clay agreed well with those of the CPT-based methods proposed by Baligh and Levadoux (1986). The values of $C_{h,NC}$ and $k_{h,OC}$ were in the range of $0.4{\sim}3.0\;cm^2/sec$ and $0.40{\sim}2.50\;cm^2/sec$, each of which slightly increases or decreases with depth, respectively. It was also inferred that these trends seem to reflect the depositional environments of the clay.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.485-500
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• 2020

Due to various advantages such as small facilities, ease of construction and so on, the grouting technology which is widely used in construction field has developed remarkably compared with the past. However, the efforts to improve the homogeneity of quality, long-term durability and environmental problems have been continued. In recent years, new grouting method has been developed in order to solve problems such as low strength, durability and leaching phenomenon of liquid glass (sodium silicate) grouting material in Korea. A newly developed method integrates the injection material with the ground by the self-healing material of crystallization growth type. For this reason, it is known that improvement of the durability and water quality of the ground, prevention of leaching, and environment friendliness can be expected. The present study applied a newly developed method to test sites and verified its effect such as injection range, improvement effect, waterproofing performance and so on. Standard penetration test, field permeability test, borehole shear test, pressuremeter test and pH test were conducted, and the results were compared between before and after developed method application. As results of tests, the field applicability and improvement effect of developed method were proved to be excellent.

• Journal of the Korean Geotechnical Society
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• v.26 no.1
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• pp.21-33
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• 2010

In this paper, the consolidation and the permeability characteristics of Songdo were evaluated based on the laboratory and field tests. The test results indicate that silty clay layer above approximately E.L-15 m are consolidation layer, and sand layers embedded in consolidation layers are drainage layers. Consolidation layer was overconsolidated state before the reclamation work; however, it transferred to normalized state after the reclamation work. In addition, the average and the range of consolidation properties and magnitude of anisotropy of coefficient of consolidation were evaluated according to the soil types such as clay, silty, and clayey silt since these properties are sensitive to soil types. These analysis results can be used as preliminary design parameters of consolidation and permeability m Songdo area.

• Journal of the Korean earth science society
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• v.29 no.5
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• pp.396-407
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• 2008

Hydrogeologic properties of a well field around middle mountainous areas in Pyosun, Jeju volcanic island were examined based on water level monitoring, geologic logging and pumping test data. Due to the alternating basaltic layers with varying permeability in the subsurface, it is difficult to analyze the hydraulic responses to artificial pumping and/or natural precipitation. The least permeable layer, detrital materials with clay, is found at a depth of 200 m below surface, but it is not an upper confining bed for lower main aquifer. Nevertheless, this layer may serve as a natural barrier to vertical percolation and to contaminant migration. Water levels of the production wells are dominantly affected by pumping frequently, while those of the remote observation wells are controlled by ambient precipitation. Results of pumping tests revealed a possible existence of horizontal anisotropy of transmissivity. However, some results of this study include inherent limitations enforced by field conditions such as the consistent of groundwater production and the set of time periods for the cessation of the pumping prior to pumping tests.

• Magazine of the Korean Society of Agricultural Engineers
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• v.25 no.4
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• pp.69-79
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• 1983

The objective of this study is to analyze the present situation of compaction equipment used in the earth fill dam construction, and the compaction effects of varions types of equipment on core and pervious zones of the fill dam. The results obtained are summarized as follows; 1. Banking materials mostly used for the core zone were soils classified as CL, SC and ML, while those classified as SM, ML and SC were predominant for the pervious zone. 2. Equipments used practically in the real fields were considerably different from those specified in the designs. 3. It was found that the relationship between optimum water content and maximum dry density for both core and pervious materials showed to be linear, ranging from 10% to 25% water content. That is, ${\gamma}$dmax (core) = 2.2555-0.0284 Wopt ${\gamma}$dmax(pervious) =2.239-0.028 Wopt 4. The generalized compaction guides for all kinds of equipment and soil types consi- dered in this study may be recommended as N=8-10 T=2Ocm, N=10-12 T=3Ocm for core zone(98%) and N=6-8 T=2Ocm, N=8-10 T=3Ocm for pervious zone (95%). 5. The coefficient of permeability in the field tests showed abont 10 times as high as the laboratory test value. This large deviation, however, was due to the horizontal permeation and considered not to be significant in the light of the satisfactory compaction ratio in the field compac- tion.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.43-71
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• 1999

This research is an experimental work of developing a construction material using municipal wastewater sludge as liner and cover materials for waste disposal landfill. Weathered granite soil and flyash, produced as a by-product in the power plant, were used as the primary additives to improve geotechnical engineering properties of sludge. For secondary additives, bentonite and cement were mixed with sludge to decrease the permeability and to increase the shear strength, respectively. Various laboratory test required to evaluate the design criteria for liner and cover materials, were carried out by changing the mixing ratio of sludge with the additives. Basic soil properties such as specific gravity, grain size distribution, liquid and plastic limits were measured to analyze their effects on permeability, compaction, compressibility and shear strength properties of mixtures. Laboratory compaction tests were conducted to find the maximum dry densities and the optimum moisture contents of mixtures, and their effectiveness of compaction in field was consequently evaluated. Permeability tests of variable heads with compacted samples, and the stress-controlled consolidation tests with measuring permeabilities of samples during consolidation process were performed to obtain permeability, and to find the compressibility as well as consolidational coefficients of mixtures, respectively. To evaluate the long term stability of sludges, creep tests were also conducted in parallel with permeability tests of variable heads. On the other hand, for the compacted sludge decomposed for a month, permeability tests were carried out to investigate the effect of decomposition of organic matters in sludges on its permeability. Direct shear tests were performed to evaluate the shear strength parameters of mixed sludge with weathered granite, flyash and bentonite. For the mixture of sludge with cement, unconfined compression tests were carried out to find their strength with varying mixing ratio and curing time. On the other hand, CBR tests for compacted specimen were also conducted to evaluate the trafficability of mixtures. Various test results with mixtures were assessed to evaluate whether their properties meet the requirements as liner and cover materials in waste disposal landfill.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.33-39
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• 2012

The functional evaluation of constructed permeable pavements was conducted in terms of water permeable performance and noise reduction measurements in Seoul city. The field measurements of noise was based on two methods such as pass-by and novel close proximity(NCPX). The pass-by test and NCPX method are related to noise propagation and tire/pavement interaction noise measurement, respectively. For the water permeable tests, five sections were chosen; furthermore, the measurements were conducted for both of wheel path and non-wheel path area. For the pass-by measurement, three sections were chosen; furthermore, two different locations, which were near measurement point to traffic noise and far measurement point inside park or hosing complex, were selected for each section. Finally, tire/pavement interaction noise measurements were carried out at four locations. The results show that the functional performance of water permeability and noise reduction was well remained within 2 or 3 years after permeable pavement construction.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.653-657
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• 2005

This study applied the NDS method to the creek levee and the foundation of a building, for the purpose of ground improvement and cut-off. The conclusions are shown in the following. (1) The results of the field tests in the creek levee are as follows; the N value of the standard penetration test is $2{\sim}3$ before NDS grout and $9{\sim}21$ after NDS grout; in the alluvial layer, $7{\sim}11$ before NDS grout and $14{\sim}23$ after NDS grout. This confirms increasing ground strength with consistency ranging from stiff to very stiff. (2) The result of the permeability test in the creek levee shows that the ground had a great hydraulic conductivity with complete leakage before ground improvement but that the hydraulic conductivity has significantly increased to $3.17{\times}10^{-5}{\sim}4.65{\times}10^{-5}cm/sec$ after ground improvement by the NDS method. (3) The result from the field test of the foundation of the building confirms great reinforcing effects, showing that the allowable bearing capacity has increased from Pa = 5.0 $t/m^2$ before reinforcement to Pa = 25.0 $t/m^2$ after reinforcement.

• Journal of Oriental Neuropsychiatry
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• v.31 no.3
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• pp.149-156
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• 2020

Objectives: The purpose of this study was to experimentally assess the effects of Chengsimyeonjatanggagam extracts in the animal model regarding ADHD related symptoms and indicators. Methods: The experimental group was classified into the normal group (WKY rat) in 7, the control group (SHR rat) in 7, the low-concentration group of herbal medicines (SHR rat) in 7, and the high-concentration group of herbal medicines (SHR rat) in 7 by random sampling. The open field test was conducted three times on the 7th, 14th, and 21st days during the oral medication. After that, Y-maze test, intestinal permeability verification (L/M ratio), and Western blotting (CDK expression in the cerebral cortex) were performed in sequence. Results: The Chengsimyeonjatang-gagam extracts reduced the activity distance in the SHR rat at 21 days in the low and high concentration groups by the open field test. It also reduced the cross-action rate in the low and high concentration groups by the Y-maze test. And the low concentration group showed 52.3% decrease in the L/M ratio compared to the SHR group. Finally, the CDK5 protein significantly increased in the low and high concentration groups. Conclusions: This study suggests that the Chengsimyeonjatang-gagam extracts have potential to be used for the treatment of ADHD.