• Journal of the Korean Geotechnical Society
• /
• v.37 no.8
• /
• pp.5-13
• /
• 2021

Liquefaction behaviors of two natural silty samples containing fines including clay of 50% or more (Sample No.1 was silt 44.1% and clay 8.8%, sample No.2 was silt 57.2% and clay 12.4%) were examined by a cyclic triaxial test. According to the results on samples containing 50% or more of fine particles, an increase in the fine content decreases the liquefaction resistance of the sample. In other words, when the fine content increases, the liquefaction state of sample is reached with a small number of cyclic loads. In the relationship between the excess pore water pressure ratio and the number of cycles, the slope of the excess pore water pressure ratio increases more steeply as the fine content increases. As a result of analyzing the liquefaction behavior of the two silts with the content of clay contained in the fines, liquefaction occurred more easily in the No.2 silt with high clay content. This result shows that the clay contained in the fines affects the liquefaction behavior of the silt.

• Geomechanics and Engineering
• /
• v.13 no.1
• /
• pp.79-97
• /
• 2017

Natural clays exhibit features such as structural and anisotropy. In this work, a constitutive model that is able to replicate these two salient features of natural clays is presented. The proposed model is based on the classical S-CLAY1 model, where the anisotropy of the soil is captured through the initial inclination and rotation of the yield surface. To account for the structural of the soil, the compression curve of the reconstituted soil is taken as the reference. All parameters of the proposed constitutive model have clear physical meanings and can be conveniently determined from conventional triaxial tests. This proposed model has been used to simulate the behavior of soft soil in the undrained triaxial tests and the performance of Murro embankment in terms of settlement and horizontal displacements during embankment construction and consolidation stage. Results of numerical simulations using proposed model have been compared with the field measurement data. The comparisons show that the two features significantly influence the prediction results.

• Geomechanics and Engineering
• /
• v.18 no.3
• /
• pp.299-313
• /
• 2019

This research investigated the nonlinear compressibility, permeability, the yielding due to structural degradation and their effects on consolidation behavior of structured soft soils. Based on oedometer and hydraulic conductivity test results of natural and reconstituted soft clays, linear log (1+e) ~ $log\;{\sigma}^{\prime}$ and log (1+e) ~ $log\;k_v$ relationships were developed to capture the variations in compressibility and permeability, and the yield stress ratio (YSR) was introduced to characterize the soil structure of natural soft clay. Semi-analytical solutions for one-dimensional consolidation of soft clay under time-dependent loading incorporating the effects of soil nonlinearity and soil structure were proposed. The semi-analytical solutions were verified against field measurements of a well-documented test embankment and they can give better accuracy in prediction of excess pore pressure compared to the predictions using the existing analytical solutions. Additionally, parametric studies were conducted to analyze the effects of YSR, compression index (${\lambda}_r$ and ${\lambda}_c$), and permeability index (${\eta}_k$) on the consolidation behavior of structured soft clays. The magnitude of the difference between degree of consolidation based on excess pore pressure ($U_p$) and that based on strain ($U_s$) depends on YSR. The parameter ${\lambda}_c/{\eta}_k$ plays a significant role in predicting consolidation behavior.

• Journal of the Korean Chemical Society
• /
• v.50 no.4
• /
• pp.321-327
• /
• 2006

red 1 and acid blue 92, anionic dyes, were removed from synthetic wastewater by the surfactant-modified clay minerals. Two different clays, such as Korean clay(M78) and Japanese clay(KJ) were treated with three different sulfactants, CTMA, DSDMA and TMSA. The surfactant-modified clay minerals such as M-1(CTMA), M-3(TMSA), KJ-1(CTMA) and KJ-3(TMSA), showed high removal efficiencies with dyes, while M-2(DSDMA) and KJ-2(DSDMA) could adsorb both dyes with relatively low efficiencies. Furthermore, almost 100% absorption of both dyes onto M-1(CTMA) and KJ-3(TMSA) revealed the possibility that these materials can be used for the removal of hazardous organic dyes from wastewater.

• Geomechanics and Engineering
• /
• v.34 no.5
• /
• pp.473-480
• /
• 2023

Acid rain of soils has a significant impact on mechanical properties. An X-ray diffraction test, scanning electron microscope (SEM) test, laser particle size analysis test, and triaxial unconsolidated undrained (UU) test were carried out in red clay soils with different compaction degrees under the effect of different concentrations of acid. The experiments demonstrated that: the dissolution effect of acid rain on colluvium weakened with the increase in the compacting degree under the condition of certain pH values, i.e., the damage to the structure of red clay soil was relatively light, where the number of newly increased pores in the soil decreased and the agglomeration of soil particles increased; for the same compacting degree, the structural gap decreased, and the agglomeration increased with the increase in the pH value (acidity decreases) of the acid rain; the dissolution rate of Si, Al, Fe, and other elemental minerals and cement in red clay soil was found to be higher under the effect of acid rain, in turn destroying the original structure of the soil body and producing a large number of pores. This is macroscopically expressed as the decrease of the soil cohesion and internal friction angle, thereby reducing the shear strength of the soil body.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.26 no.3
• /
• pp.59-67
• /
• 1984

This study was carried out to find physical and mechanical properties of soil in Yongsan project area to support basic data for tidalland reclamation. The main results are as follows. 1. Most of the soils in this area consist of clay and silt, and inorganic materials. 2. Natural moisture contents are ranged from 42.2% to 92.9% initial void ratio, from 1.4 to 2.3 Therefore it takes a longtime in Settlement of considerable depth. 3. Wet unit weights decrease with increasing of the nataral moistare contents as rt=2. 005-0. 0065wn.4. The relationships between compression index. and liquid limit, initial void ratio and natural moisture contents are found as follows respectively. Cc =0. 046+0. O12LL Cc=-0. 068+0.367eo Cc =0. 056+0. OO8Wn 5. Natural moisture content, plastic limit, plastic index, initial void ratio and liquid :limit are directly proportional to clay content ratio. The relationships are found as Wn=26. 083+0. 797Cy PL=14. 223+0. 128Cy P1=0. 457+0. 492Cy eo=0. 757+0. O2Ocy LL=14. 695+0. 620Cy. 6. Initial void ratio and liquid limit are directly proportional to natural moisture con-tent as follows. eo=0. 310+0.022wn LL=6. 275+0.592wn

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.1174-1179
• /
• 2006

This study aims to reduce the pollutant emission for improving the IAQ by finishing with natural materials. To investigate the concentration of pollutants such as Vocs, HCHO, both the chamber experiment and field measurement were conducted. The results of the study can be summarized as flows. (1) According to the chamber experiment of pollutant-emitting porwer of diatomite materials showed that VOCs and formaldehyde emission rates were lower and satisfied to the most on the HB Grade. (2) The field measurement of pollutant-emitting concentration of clay materials were lower 35% than other materials. (3) The Vocs and formaldehyde were most emitted from furnitures and the emission rate were found to be proportional to indoor air temperature. To control the emitted pollutants efficiently, the reasonable selection of finishing with natural materials are required.

• Korean Journal of Environmental Agriculture
• /
• v.18 no.4
• /
• pp.366-371
• /
• 1999

This study was conducted to examine the change of nitrogen in soils treated by cow manure originated from the clay mineral feeding. Bentonite, zeolite, and porphyry were feeded. CEC of the porphyry showed the lowest value, 12.02 cmol/㎏, among three kinds of clay mineral. The manure treated soils were incubated at 14, 18, 22, $25^{\circ}C$. CEC of the manure after bentonite, zeolite, porphyry feeding were 147.5, 137.0, and 114.0 cmol(+)/㎏, respectively. These values were higher than that of non-mineral treated manure, 107.5 cmol(+)/㎏. After 8 weeks incubation, there were no significant difference in the content of $NH_4-N$, but the content of $NO_3-N$ in soils were in order of zeolite treated > bentonite treated > porphyry treated > non-nimeral treated. These results suggested that the clay mineral adsorbed $NH_4\;^+-N$ and prevent the loss of nitrogen from soils.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.47 no.3
• /
• pp.12-21
• /
• 2019

In order to investigate the effect of various pavement materials (artificial grass, natural grass, and clay sand) on the human thermal environment, the microclimate data in early autumn (air temperature, humidity, wind speed, and shortwave and longwave radiation) were measured and compared on each surface. The mean air temperature, humidity and wind speed of the pavement materials did not differ significantly and showed the greatest difference in the mean radiant temperature. Natural grass, which has the highest albedo, has the highest amount of shortwave radiation. The artificial turf had the highest surface temperature and the highest amount of longwave radiation. In the human thermal environment index PET, artificial grass > clay sand > natural grass. Natural grass had a maximum 2/3 level lower and a mean 1/2 level lower in PET as compared to artificial grass. The clay sand pavement had a maximum 2/3 level lower and a mean 1/3 level lower than the artificial grass. Natural grass had a maximum 1/3 level lower than the clay sand pavement. Their UTCIs showed smaller differences than the PETs. Therefore, it is necessary to carefully choose materials from the planning stage when designing outdoor spaces, including playgrounds.

• Korean Chemical Engineering Research
• /
• v.55 no.5
• /
• pp.685-689
• /
• 2017

We studied the removal of zinc ions from synthetic brackish water by an adsorption method using natural Algerian Bentonite (NAB). The effect of the main physico chemical parameters-contact time, pH, temperature, ionic strength, clay weight and initial metal ion concentrations on the removal of $Zn^{+2}$-were investigated. The results showed that equilibrium was attained within 10 min of stirring time. The retention capacity of $Zn^{+2}$ increased with the increase of pH, the adsorbent dose and ionic strength. A modelization study showed that the adsorption follows Langmuir isotherm, while its kinetics was pseudo-second-order. Based on the results, it was concluded that NAB, which is natural and available, could be used as an alternative for the removal of zinc from saline aqueous solutions.