• Title/Summary/Keyword: Soil Improvement

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Comparative study of individual and co-application of biochar and wood vinegar on growth of perilla (Perilla frutescens var.) and soil quality

  • Yun-Gu Kang;Nam-Ho Kim;Jun-Ho Kim;Da-Hee Ko;Jae-Han Lee;Jin-Hyuk Chun;Taek-Keun Oh
    • Korean Journal of Agricultural Science
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    • v.49 no.2
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    • pp.357-366
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    • 2022
  • Biochar can be obtained by using various types of biomass under an oxygen-limited condition. Biochar can be utilized for various applications such as soil improvement, waste management, growth promotion, and adsorption. Wood vinegar is produced by the process of pyrolysis wood biomass and is used as a growth promoter, for soil improvement, and as a feed additive. When wood vinegar is treated on soil, it acts to control soil pH, improve nutrient availability, and alleviate N2O and NH3 volatilization. The objective of this study was to evaluate the effect of biochar and wood vinegar on the growth of perilla and soil quality. The experiment was conducted by using a Wagner pot (1·5,000 a-1) in a glass greenhouse. The biochar was produced by pyrolysis at 450℃ for 30 minutes using rice husk and rice straw. Wood vinegar was diluted to 1 : 500 (v·v-1) and used in this experiement. In the results of a cultivation experiment, co-application of biochar and wood vinegar enhanced the growth of perilla. In particular, rice husk biochar affected the leaves of the perilla, and rice straw biochar influenced the stems of the perilla. In addition, soil quality after treatment with biochar and wood vinegar applied together was highest compared to other units. Therefore, it is anticipated that co-application of biochar and wood vinegar will be more productive and improve soil quality compared to individual utilization of biochar and wood vinegar.

Stability of rectangular tunnel in improved soil surrounded by soft clay

  • Siddharth Pandey;Akanksha Tyagi
    • Geomechanics and Engineering
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    • v.34 no.5
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    • pp.491-505
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    • 2023
  • The practical usage of underground space and demand for vehicular tunnels necessitate the construction of non-circular wide rectangular tunnels. However, constructing large tunnels in soft clayey soil conditions with no ground improvement can lead to excessive ground deformations and collapse. In recent years, in situ ground improvement techniques such as jet grouting and deep cement mixing are often utilized to perform cement-stabilisation around the tunnel boundary to prevent large deformations and failure. This paper discusses the stability characteristics and failure behaviour of a wide rectangular tunnel in cement-treated soft clays. First, the plane strain finite element model is developed and validated with the results of centrifuge model tests available in the past literature. The critical tunnel support pressures computed from the numerical study are found to be in good agreement with those of centrifuge model tests. The influence of varying strength and thickness of improved soil surround, and cover depth are studied on the stability and failure modes of a rectangular tunnel. It is observed that the failure behaviour of the tunnel in improved soil surround depends on the ratio of the strength of improved soil surround to the strength of surrounding soil, i.e., qui/qus, rather than just qui. For low qui/qus ratios,the stability increases with the cover; however, for the high strength improved soil surrounds with qui >> qus, the stability decreases with the cover. The failure chart, modified stability equation, and stability chart are also proposed as preliminary design guidelines for constructing rectangular tunnels in the improved soil surrounded by soft clays.

An Experimental Study on the Effect of Consolidation Improvement Using Horizontal Drains (수평배수재를 이용한 압밀개량효과에 대한 실험연구)

  • 김지용;김정기;장연수;김수삼
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.33-40
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    • 2000
  • The horizontal drain method is one of the soil improvement methods in reclamation works using dredged soils. In this method, plastic drain boards are installed horizontally in the ground, and a seepage pressure or negative pressure is applied through one end of these drains. In this study, a basic consolidation test using horizontal drains was conducted to investigate the effectiveness of this method. The configuration of soil box which was used in this test is 100cm(B)${\times}$100cm(L)${\times}$85cm(H). The drain board was reduced to 25mm${\times}$5mm. The variations in settlement and volume of drain water during the consolidation process were measured, and the distribution of water content and the transpormation of horizontal drain were investigated.

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Compaction and strength behavior of lime-coir fiber treated Black Cotton soil

  • Ramesh, H.N.;Manoj Krishna, K.V.;Mamatha, H.V.
    • Geomechanics and Engineering
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    • v.2 no.1
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    • pp.19-28
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    • 2010
  • This paper describes the compaction and strength behavior of black cotton soil (BC soil) reinforced with coir fibers. Coir used in this study is processed fiber from the husk of coconuts. BC soil reinforced with coir fiber shows only marginal increase in the strength of soil, inhibiting its use for ground improvement. In order to further increase the strength of the soil-coir fiber combination, optimum percentage of 4% of lime is added. The effect of aspect ratio, percentage fiber on the behavior of the composite soil specimen with curing is isolated and studied. It is found that strength properties of optimum combination of BC soil-lime specimens reinforced with coir fibers is appreciably better than untreated BC soil or BC soil alone with coir fiber. Lime treatment in BC soil improves strength but it imparts brittleness in soil specimen. BC soil treated with 4% lime and reinforced with coir fiber shows ductility behavior before and after failure. An optimum fiber content of 1% (by weight) with aspect ratio of 20 for fiber was recommended for strengthening BC soil.

Numerical Analysis on the Flow Field around Tiller Rotor for Soil Improvement in Coastal Fisheries (연안어장의 토질 개선을 위한 경운기 로터 주변의 유동장에 대한 수치해석)

  • Kim, Jang-Kweon;Oh, Seok-Hyung
    • Journal of Power System Engineering
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    • v.21 no.5
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    • pp.20-28
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    • 2017
  • The steady-state, incompressible and three-dimensional numerical analysis was performed to investigate the flow fields around the seabed tiller used for soil improvement in coastal fisheries and the pulling force and buoyancy generated by tiller operation. The turbulence model used in this study is a realizable $k-{\varepsilon}$. As a results, at a stationary current or a current speed of 1.2 knots, where rotor rotates in a clockwise direction, a typical vortex pair appears near the tip of the rotor except for the edge, and the strength of the vortex pair increases with the number of revolutions of the rotor. The pulling force of the tiller rotating in the counterclockwise direction increases with the number of revolutions. Also, when the current flows at 1.2 knots and the rotor rotates clockwise, the pulling force of the tiller acts on the upstream side irrespective of the number of rotations of the rotor, so that no force is applied. The buoyancy of the tiller acts on the seawater surface if the flow direction inside the rotor is the same as the direction of rotation of the rotor, regardless of the current velocity, otherwise it acts on the seabed.

A Study on the Ground Improvement by Compaction Grouting System (C.G.S에 의한 기초지반보강효과에 관한 연구)

  • 천병식;여유현;최현석;오일석
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.02a
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    • pp.1-13
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    • 1999
  • The use of Compaction Grouting evolved in the 1950's to correct structural settlement of buildings. Over the almost 50 years, the technology has developed and is currently used in wide range of applications. Compaction Grouting, the injection of a very stiff, 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. Major uses of Compaction Grouting include densifying loose soils or fill voids caused by sinkholes, poorly compacted fills, broken utilities, improper dewatering, or soft ground tunneling excavation. Other application include preventing liquefaction, re-leveling settled structures, and using compaction grout bulbs as structural elements of minipiles or underpinning. The technique replaced slurry injection, or 'pressure grouting', as the preferred method of densification grouting. There are several reasons for the increased use of Compaction Grouting which can be summarized in one word: CONTROL. The low slump grout and injection processes are usually designed to keep the grout in a homogeneous mass at the point of injection, while acceptable in some limited applications, tends to quickly get out of control. Hydraulic soil fracturing can cause extensive grout travel, often well beyond the desired treatment zone. So, on the basis of the two case history constructed in recent year, a study has been peformed to analyze the basic mechanism of the Compaction Grouting and verify the effectiveness of the ground improvement using some test methods.

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A Study on Landscape Improvement of Cut-Slopes and Management of Non-Point Pollution Using Coir-Blocks (코이어블록(Coir-Blocks)을 이용한 절토사면의 경관개선 및 비점오염원 관리에 관한 연구)

  • Lee, Kwan-Choon;Park, Yool-Jin
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.18 no.5
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    • pp.27-36
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    • 2015
  • This study was conducted to grasp the effect of afforestation of cut slope using coir blocks on the improvement of scenery and the management of non point pollution source. Total four experimental tanks such as general soil slope, coir blocks, installation slope, slope refilling the inside of coir blocks slope with pebble, slope refilling the inside of coir blocks with soil and plant were installed, pollution source water was supplied and the possibility of reduction management of non point pollution source was analyzed at four items of COD, SS, T-N, T-P and main results drawn from this study are as follows. In conclusion, biodegradable materials like coir blocks and soil and plant layers are judged to be helpful in reduction management of non point pollution source inflowing to water space from land area. Thus, the reduction of non point pollution source occurring at land area is thought to be fully controlled at the cut slope, the space prior to inflowing to water ecological space like a stream or a swamp area.

Shear Strength Characteristics of Dredged Soil with Oyster Shell Binder (굴패각 고화재를 혼합한 준설토의 전단특성)

  • Lee, Sangjin;Yoon, Gillim;Lee, Yoongyu;Lee, Kidong;Kang, Ingyu;Kim, Hongtaek;Baek, Seungcheol
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.1
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    • pp.27-32
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    • 2007
  • Trafficability for construction equipments in soft ground should be secured by improving the surface course. For this situation, the ground improvement technique has been used with stiffening agent, but the improvement cement has been mostly used so far. However, oyster shell has been developed and used as the stiffening agent to expand the chance of recycling oyster shell, which is regarded as solid waste. In this research, it was confirmed mechanical characteristics of oyster shell as stiffening agent by analyzing the strength characteristic such as mixing rates, water contents, and curing days of that to the dredging soil.

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Effect of Long Term Fertilization on Microbial Biomass, Enzyme Activities, and Community Structure in Rice Paddy Soil

  • Lee, Chang Hoon;Kang, Seong Soo;Jung, Ki Youl;Kim, Pil Joo
    • Korean Journal of Soil Science and Fertilizer
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    • v.46 no.6
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    • pp.487-493
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    • 2013
  • The effects of long-term fertilization on soil biological properties and microbial community structure in the plough layer in a rice paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK + Compost) for last 40 years. No fertilization plot (Control) was installed for comparison. Though fertilization significantly improved rice productivity over control, the long-term fertilization of NPK and compost combination was more effective on increasing rice productivity and soil nutrient status than single application of compost or chemical fertilizer. All fertilization treatments had shown significant improvement in soil microbial properties, however, continuous compost fertilization markedly increased soil enzyme and microbial activities as compared to sole chemical fertilization. Results of microbial community structure, evaluated by EL-FAME (ester-linked fatty acid methyl esters) method, revealed big difference among Control, NPK, and Compost. However, both Compost and Compost+NPK treatments belonged to the same cluster after statistical analysis. The combined application of chemical fertilizer and organic amendments could be more rational strategy to improve soil nutrient status and promote soil microbial communities than the single chemical fertilizer or compost application.

Changes of Soil Properties and Temperature by Green Manure under Rice-based Cropping System

  • Jeon, Weon-Tai;Kim, Min-Tae;Seong, Ki-Yeong;Lee, Jong-Ki;Oh, In-Seok;Park, Sung-Tae
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.53 no.4
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    • pp.413-416
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    • 2008
  • The cultivation of green manure crop is considered as a good management practice by increasing soil organic matter and fertility levels. This experiment was conducted to improve the soil environment under rice-based cropping system at paddy soil (fine loamy, mixed, nonacid, mesic, family of Aeric Fluventic Haplaquepts) in National Institute of Crop Science (NICS), Korea in 2006 to 2007. The variation of soil temperature in green manure plots was lower than without green manure (control) during spring season (April to May). The temperature variation of no tillage plot (broadcast before rice harvest) was the lowest among treatments. After green manure cropping, the soil bulk density and porosity ratio were improved at the top soil. The production of green manure was the highest athairy vetch and barley mixture plot by partial tillage. However, mixture treatment had no improvement on soil organic matter. After rice cropping with green manure application, soil quality was improved such as soil physical properties except mixture treatment. Therefore, we suggest that soil quality should be improved by green manure cultivation under rice-based cropping system.