• Title/Summary/Keyword: sand column

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Numerical analysis of an innovative expanding pile under static and dynamic loading

  • Abdullah Cheraghi;Amir K. Ghorbani-Tanha
    • Geomechanics and Engineering
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    • v.32 no.4
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    • pp.453-462
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    • 2023
  • Designing pile foundations subjected to the uplift forces such as buildings, oil platforms, and anchors is becoming increasingly concerned. In this paper, the conceptual design of a new type of driven piles called expanding pile is presented and assessed. Some grooves have been created in the shaft of the novel pile, and some moveable arms have been designed at the pile tip. At first, static analyses using the finite element method were performed to evaluate the effectiveness of the innovative pile on the axial bearing capacity. Then its effect on seismic behavior of moment frame is considered. Results show that the expanding arms were provided an ideal anchorage system because of the soil's noticeable locking-up effect increasing uplift bearing capacity. For example at the end of the static tensile loading procedure, displacement decrement up to 55 percent is observed. In addition, comparing the uplift bearing capacity of the usual and new pile with different lengths in sand and clay layers shows noticeable effect and sharp increase up to about two times especially in longer piles. Besides, a sensible reduction in the seismic response and the stresses in the beam-column connection between 23-36 percent are achieved that ensures better seismic behavior of the structures.

Investigating the combination of natural and crushed gravel on the fresh and hardened properties of self-compacting concrete

  • Moosa Mazloom;Mohammad Ebrahim Charmsazi;Mohammad Hosein Parhizkari
    • Structural Monitoring and Maintenance
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    • v.11 no.1
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    • pp.1-18
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    • 2024
  • Self-compacting concrete is widely used around the globe today due to its special and unique properties. This study examines the effect of natural and crushed gravel combinations in different percentages in short-and long-term properties of concrete. The best utilized sand had a fineness modulus of 2.7. In the mentioned mix designs, silica fume was used with 0 and 7% of the weight of the cement. In order to check the properties of fresh and hardened concrete, 9 and 5 test types were performed, respectively. The carried out tests were slump flow, V-funnel, J-ring, L-box, U-box and column segregation for fresh concrete, and compressive, tensile and flexural strengths for hardened concrete. A mix with only 100% natural gravel was considered as the control mix. According to the results, the control mix design and the one containing 100% crushed gravel with silica fume were the best in fresh and hardened concrete tests, respectively. Finally, using the optimization method, a mix design with 25% natural gravel, 75% crushed gravel and silica fume was introduced as the best mix in terms of the results of both fresh and hardened concrete tests.

Effects of Capillary Rise Interruption Layer on Salt Accumulation and Kentucky Bluegrass (Poapratensis L.) Growth in Sand Growing Media Established Over the Reclaimed Saline Soil (임해 간척지에서 모래상토 층에 모세관수 차단 층의 도입이 염류 집적과 켄터키블루그래스 생육에 미치는 영향)

  • Rahayu, Rahayu;Yang, Geun-Mo;Choi, Joon-Soo
    • Proceedings of the Turfgrass Society of Korea Conference
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    • 2011.02a
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    • pp.5-8
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    • 2011
  • This research was conducted to determine the effect of capillary rise interruption layer on the sand based growing media when growing Kentucky bluegrass under soil reclamation and saline water irrigation. Rootzone profile consists of three layers as top soil of 30 cm, 20 cm of capillary interruption layer and 10 cm of reclaimed paddy soil. Rootzone profile was packed in column pots. The top soil was a mixture of sand dredged up from Lake Bhunam Tae Ahn, Korea and peat at the ratio of 95:5 by volume. Bottom part of column was covered with plastic net and the pots were soaked into 5 cm depth saline water reservoir with salinity $3-5dsm^{-1}$. Kentucky bluegrass was installed by sod and irrigated using $2dSm^{-1}$ saline water(5.7mm $day^{-1}$)in 3days interval. The results showed that the largest accumulation of salt in the spring with ECe of $5.4dSm^{-1}$ and SAR34.0 in rootzone with out capillary rise interruption layer and ECe of $4.6dSm^{-1}$ and SAR8.24 at rootzone using gravel as capillary rise interruption layer material. Kentucky bluegrass grown in growing media with gravel as capillary rise interruption layer resulted in the average visual quality rate of 8.1and clipping dry weight of $24.8gm^{-2}$, while Kentucky bluegrass grown in the growing media with out capillary rise interruption layer showed the visual quality rate of 7.9 and clipping dry weight of $34g.m^{-2}$. Capillary rise interruption layer of gravel and coarses and enhanced the visual quality by 4.1and 4.0%, root length by 50 and 38%, and root dryweight by 35and 17% of Kentucky bluegrass, and reduced the accumulation of Na by 16% and 25%, ECe by 7% and 13% in the rootzone.

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Degradation of TPHs, TCE, PCE, and BTEX Compounds for NAPLs Contaminated Marine Sediments Using In-Situ Air Sparging Combined with Vapor Extraction (증기추출법과 결합된 공기주입법을 이용한 비수용성액체 해양퇴적물의 TPHs, TCE, PCE 및 BTEX 정화)

  • Lee, Jun-Ho;Han, Sun-Hyang;Park, Kap-Song
    • Economic and Environmental Geology
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    • v.46 no.5
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    • pp.425-444
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    • 2013
  • This study was carried out in order to determine the remediation of total petroleum hydrocarbons (TPHs), trichloroethylene (TCE), perchloroethylene (PCE), benzene, toluene, ethylbenzene and xylenes (BTEX) compounds for non-aqueous phase liquids (NAPLs) using in-situ air sparging (IAS) / vapor extraction (VE) with the marine sediments of Mandol, Hajeon, Sangam and Busan, South Korea. Surface sediment of Mandol area had sand characteristics (average particle size, 1.789 ${\Phi}$), and sandy silt characteristics (average particle size, 5.503 ${\Phi}$), respectively. Sangam surface sediment had silt characteristics (average particle size, 5.835 ${\Phi}$). Sediment characteristics before experiment in the Busan area showed clay characteristics (average particle size, 8.528 ${\Phi}$). TPHs level in the B1 column of Mandol, Hajeon, Sangam, and Busan sediments were 2,459, 6,712, 4,348, and 14,279 ppm. B2 (3 L/min) to B5 (5 L/min) columns reduced 99.5% to 100.0% of TCE and 93.2% to 100.0% of PCE. Removal rates of TCE, PCE, and BTEX are closely correlated (0.90-0.99) with particle sizes and organic carbon concentrations. However, TPHs (0.76) and benzene (0.71) showed the poorer but moderate correlations with the same parameters.

A Study on Transport Characteristics of CMC-modified Zero Valent Iron (ZVI) Nanoparticles in Porous Media (다공성 매질내에서 CMC로 표면개질된 영가철 나노입자의 이동 특성에 관한 연구)

  • Cho, Yun-Chul;Choi, Sang-Il
    • Journal of Soil and Groundwater Environment
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    • v.14 no.6
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    • pp.101-107
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    • 2009
  • Carboxymethyl cellulose (CMC) as stabilizer is expected to facilitate in-situ delivery of zero-valent iron (ZVI) nanoparticles in a contaminated aquifer because it increases dispersity of ZVI nanoparticles. This work investigated the transport of CMC-stabilized ZVI nanoparticles (CMC-Fe) using column breakthrough experiments. The ZVI nanoparticles (100 mg/L Fe) were transportable through sand porous media. In contrast, non-stabilized ZVI nanoparticles rapidly agglomerate in solution and are stopped in sand porous media. At pH 7 of solution approximately 80% CMC-Fe were eluted. When the pH of solution is below 5, 100% CMC-Fe were eluted. These results suggest that the mobility of CMCFe was increased as pH decreases. In the mobility test under different ionic strengths using $Na^+$ and $Ca^{2+}$ ions, there was no signigficant difference in the mobility of CMC-Fe. Also, in the experiments of effect of clay and natural organic mater (NOM) on the mobility of ZVI, there was no significant difference in the mobility of CMC-Fe not only between 1 and 5% clay, but 100 and 1000 mg/L NOM. The results from this work suggests that the CMC-Fe nanoparticles could be easily delivered into the subsurface over a broad range of ionic strength, clay and NOM.

Feasibility Evaluation for Remediation of Groundwater Contaminated with Heavy Metal using Calcium Polysulfide in Homogeneous media (균질한 매질 내 Calcium polysulfide 주입에 따른 고농도 중금속 오염 지하수 정화 타당성 검토)

  • Hyeon Woo Go;Jin Chul Joo;Kyoungphile Nam;Hee Sun Moon;Sung Hee Yoon;Dong Hwi Lee;So Ye Jang
    • Journal of Soil and Groundwater Environment
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    • v.28 no.1
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    • pp.1-14
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    • 2023
  • In this study, column tests using relatively uniform Jumunjin sand media were conducted to evaluate the feasibility of calcium polysulfide (CaSx, CPS) in removing high concentration of Zn2+ in groundwater. The injected CPS solution reacted rapidly with Zn2+ in artificial groundwater and effectively reduced Zn2+ by more than 99% through metal sulfide precipitation. Since the density (d = 1.27 g/cm3 ) of CPS solution was greater than that of water, CPS solution settled down rapidly while capturing Zn2+ and formed stable CPS layer similar to dense nonaqueous phase liquid. Mass balance analysis on Zn2+ in CPS solution suggested that CPS solution effectively reacted with Zn2+ to form metal sulfide precipitates except for high groundwater seepage velocity of 400 cm/d. With greater groundwater seepage velocity, injected CPS did not completely dissolve at the CPS-water interface, but a partially-misible CPS layer continuously moved and reacted with Zn2++ in the direction of groundwater flow. Since hydraulic conductivity (Kh) decreased slightly due to the generated metal precipitates in the inter-pores of media, injection of CPS solution should be optimized to prevent clogging. As evidenced by both XRF and SEM/EDS results, ZnS precipitates were clearly observed through the reaction between the CPS solution and Zn2+. Further study is warranted to evaluate the feasibility of CPS to remove high-concentration heavy metalcontaminated groundwater in complex and heterogeneous media.

Consolidation Characteristics of Soft Ground with Artesian Pressure (피압에 따른 연약지반의 압밀 거동)

  • Yun, Daeho;Kim, Jaehong;Kim, Yuntae
    • Journal of the Korean GEO-environmental Society
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    • v.17 no.2
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    • pp.31-39
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    • 2016
  • Vertical drain has usually been used to accelerate the consolidation of soft clay deposits with high moisture content. Busan thick clay deposits are subjected to artesian pressure from an aquifer in sand and gravel layers. However, effect of artesian pressure existing in drainage-installed soft ground on consolidation behaviors is not well known. This paper investigates the consolidation behavior of drainage-installed soft ground at the Nakdong river estuary with artesian pressure and without artesian pressure. A series of one-dimensional large size column test was carried out to find out the consolidation characteristics of clay. Test results indicated that total settlement of clay with artesian pressure was higher than that without artesian pressure because effective stress decreased due to upward flow. Dissipation rate of excess pore water pressure delayed and excess pore water pressure did not fully dissipate in clay layer with artesian pressure. Undrained shear strength of clay ground with artesian pressure was lower than that without artesian pressure.

An Experimental Study on Surfactant Enhanced LNAPL Removal Behavior in Saturated Zone (계면활성제를 이용한 포화지층내 저비중 비수용성 유기용매의 제거거동에 관한 연구)

  • 이재원;박규홍;박준범;임경희
    • Journal of the Korean Geotechnical Society
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    • v.15 no.5
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    • pp.291-300
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    • 1999
  • Surfactant flushing for enhancing the removal of BTEX from contaminated sand/clay mixtures was investigated. Eight soil columns packed with relatively undisturbed BTEX contaminated soils, were leached with water, methyl alcohol and then flushed with surfactant with or without several additives. Initial concentrations of BTEX mixture range from 278mg/kg to 1975mg/kg. Initial BTEX removal efficiency was 98% when the contaminated soil was flushed with water of 850 pore volumes. Because of tailing effect, water flushing could not remove below 8mg/kg concentrations during the experimental period. Eventually, the most effective surfactant for flushing was turned out to be 4% SOFTANOL(equation omitted)-90 with 3% ethyl alcohol and 3% SXS. In interrupted flow conditions, the removal efficiency was 99.5% with the flushed water of 95 pore volumes. The BTEX mixture removed from the soil columns during the surfactant flushing ranges from 84.5% to 99.5% of the initial amount for both water leaching(850 pore volumes) and surfactant flushing(95-165 pore volumes), respectively. Test results indicated that surfactant flushing could enhance the removal of BTEX mixture from contaminated soils and could reduce the aqueous phase BTEX mixture concentration in leachate.

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Molecular Size Distributions of NOM in Conventional and Advanced Water Treatment Processes (기존수처리 공정 및 고도정수처리 공정에서 NOM의 분자크기 분포 변화)

  • Choi, Il-Hwan;Jung, Yu-Jin
    • Journal of Korean Society on Water Environment
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    • v.24 no.6
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    • pp.682-689
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    • 2008
  • The purpose of this study was to find out the variation between molecular size distribution (MSD) of natural organic matter (NOM) in raw waters after different water treatment processes like conventional process (coagulation, flocculation, filtration) followed by advanced oxidation process (ozonation, GAC adsorption). The MSD of NOM of Suji pilot plant were determined by Liquid Chromatography-Organic Carbon Detection (LC-OCD) which is a kine of high-performance size-exclusion chromatography (HPSEC) with nondispersive infrared (NDIR) detector and $UV_{254}$ detector. Five distinct fractions were generally separated from water samples with the Toyopearl HW-50S column, using 28 mmol phosphate buffer at pH 6.58 as an eluent. Large and intermediate humic fractions were the most dominant fractions in surface water. High molecular weight (HMW) matter was clearly easier to remove in coagulation and clarification than low molecular weight (LMW) matter. Water treatment processes removed the two largest fractions almost completely shifting the MSD towards smaller molecular size in DW. No more distinct variation of MSD was observed by ozone process after sand filtration but the SUVA value were obviously reduced during increase of the ozone doses. UVD results and HS-Diagram demonstrate that ozone induce not the variation of molecular size of humic substance but change the bond structure from aromatic rings or double bonds to single bond. Granular activated carbon (GAC) filtration removed 8~9% of organic compounds and showed better adsorption property for small MSD than large one.

Characteristics of soil and eco-friendly media for improving the filterability and water quality in soil filtration (하천수질정화용 토양여과의 여과용량 증대와 수질 개선을 위한 친환경 여재 특성 비교)

  • Ki, Dong-Won;Cho, Kang-Woo;Won, Se-Yoen;Song, Kyung-Guen;Ahn, Kyu-Hong
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.4
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    • pp.453-462
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    • 2010
  • Nowadays, the challenges of ensuring good water quality and quantity of river are becoming more important for human society, but there has been troublesome for purifying river water. In this study, we performed the fundamental study of a river water treatment system using riverside soil and eco-friendly optimal media for improving river water quality and can also treat a large amount of river water. As the results of the physical and chemical characterization of the two different soils (Kyungan and Chungrang, The Republic of Korea), which were collected from real stream sides in the Han River basin, and five kinds of media (zeolite, perlite, steel slag, woodchip and mulch), both soils were all classified as a sand, and effective size ($D_{10}$) and uniformity coefficient (U) of the soil were about 0.2 mm and 4 or so, respectively. Through the batch and column experiments with the soil and eco-friendly media, zeolite and mulch were found to be efficient for decreasing nitrogen. In addition, steel slag was especially superior to the other media for phosphorus removal. From soil reforming tests volume ratios were 2.8, 1, and 1 of Kyungan soil, zeolite, and steel slag hydraulic conductivity of mixed soil was increased $1.30{\times}10^{-2}$ from $2.85{\times}10^{-3}$ of Kyungan soil, and the removal efficiencies of nitrogen and phosphorus were also improved. These results show that reforming of the soil enhanced the purification of a large amount of water, and zeolite, mulch, and steel slag might be facilitated as proper functional media.