Soil Conditioning Tests on Sandy and Cobbly Soil for Shield Tunneling

Zheng Zhen,Xinsheng Ge,Jun Zhang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4

Soil conditioning is an important stage in shield tunnel construction that can effectively improve muck flow plasticity, reduce cutter head wear and improve tunneling efficiency,especially in sandy and cobbly soils. The aim of this paper is to obtain the optimal ratio of residue modifiers in sandy and cobbly soil and to improve the equipment used in residue-related shield machines. Residual soil in a sandy pebble layer was selected, and particles with sizes over 50 mm were removed to form soil samples. Through laboratory tests, the optimal ratio of the modifier was obtained, and the shield tunneling machine equipment was optimized. The research results for the laboratory tests and equipment optimization were verified and adjusted appropriately through field tunneling tests. The following results were obtained. 1) A 3% foaming agent C was selected for the soil conditioning tests. The final mass ratio of the bentonite mixed solution of water, bentonite, soda ash (Na2CO3), and carboxymethylcellulose (CMC) was 6:1:0.028:0.035. 2) Improving earth pressure balance (EPB) shield machine equipment can improve the effects of soil conditioning. 3) Compared with the volume of residual soil, the optimal ratio of soil conditioning in sandy and cobbly layer was 13% water, 4 – 5% bentonite mixed solution and 12 – 15% foam. In addition, the maximum ratio shall be taken for the strata with poor grain composition. These results can be used to provide excavation guidelines for using an EPB machine under these soil conditions.

토양진압 및 비닐피복에 따른 고구마 품종 ‘금시’와 ‘산율미’의 생육 및 수량

이은섭,이용선,김희동,윤성탁 한국국제농업개발학회 2007 韓國國際農業開發學會誌 Vol.19 No.1

This experiments are conducted to clarify the effects of soil compacting and PE film mulching on growth and yield of sweet potato at Yeoju, Gyeonggido in 2005. Cultivars tested were Keumshi and Shinyulmee. Four combinations of treatment were treated such as soil compacting only, PE film mulching only, and control only. The results obtained were that vine length and vine weight of Shinyulmee was longer than that of Kumshi in the sandy soil and loamy soil, whereas number of nodes was more Shinyulmee compared to those of Keumshi in the sandy soil. Number of branches of had no significant difference between two varieties. Number of marketable tuber root per plant was more in Shinyulmee compared to that of Keumshi. In the loamy soil, weight of marketable tuber root per tuber was heaver in Shinyulmee compared to that of Keumshi. Marketable yield per 10a between two varieties of Shinyulmee and Keumshi was no significant difference. Vine length was longer, vine weight was heavier, number of nodes and branches was more at PE film mulching compared to soil compacting in the sandy and loamy soil. Number of marketable tuber root was more at PE film mulching than at soil compacting. Weight of tuber root per each and yield of marketable tuber root per 10a was higher at PE film mulching compared to soil compacting. Starch value and starch yield per 10a between two varieties of Keumshi and Shinyulmee had no difference. In the sandy loam and loamy soil, starch yield per 10a was higher at PE film mulching compared to soil compacting. Starch value between soil compacting and PE film mulching and between cultivars tested had no significant difference. 본 시험은 2005년 웰빙식품으로 각광을 받고 있는 단방추형이며 분상질인 밤고구마를 경기지역을 대표하는 특산품으로 지속적으로 안전생산 가능성을 검토하고자 토성은 사양토와 양토를 대상으로, 시험품종은 ‘금시’와 ‘신율미’로, 그리고 토양진압과 비닐피복유무에 따른 고구마의 생육 및 수량과 품질을 검토하였다. 이 연구에서 얻어진 연구결과는 다음과 같다. 토성에 관계없이 금시보다 신율미가 넝쿨길이는 길었고, 넝쿨중량 무거웠으나, 절수는 양토에서만 금시보다 신율미가 많았으며, 분지수는 차이가 없었다. 주당 상저수는 양토에서 금시가 신율미보다 많았고, 괴근당 상저중은 토성에 관계없이 금시보다 신율미가 무거웠다. 10a당 총저중과 상저중은 두 품종 간에 차이가 없었다. 토성에 관계없이 토양진압보다는 비닐피복에 의한 효과가 커서 비닐피복 조합이 토양진압조합구보다 넝쿨길이는 길었고, 분지수와 절수는 많았으며, 넝쿨중량은 무거웠다. 또한 상저수는 많았고, 괴근당 상저중은 무거웠으며 10당 총저수량과 10a당 상저수량은 높았다. 근형지수는 토양에 관계없이 금시보다 신율미가 높았고, 전분가와 10a당 전분수량은 차이가 없었다. 토양진압과 비닐피복 조합을 하였을 때, 근형지수는 양토에서 품종에 관계없이 토양진압조합보다 비닐피복조합에서 길었고, 10a당 전분수량은 토성에 관계없이 비닐피복조합에서 높았으나, 전분가는 품종간, 토양진압과 비닐피복조합간에 차이가 없었다. 토양진압과 비닐피복에 대한 효과분석 결과, 생육 및 수량형질에서 토양진압보다 비닐피복효과가 컸으나, 근형지수는 양토에서, 전분수량은 품종이나 토성에 관계없이 토양진압보다 비닐피복에서 효과적이었다.

Development of a sandy soil water content monitoring system for greenhouses using Internet of Things

Mohammod Ali,Md Razob Ali,Md Ashrafuzzaman Gulandaz,Md Asrakul Haque,Md Sazzadul Kabir,Sun-Ok Chung 사단법인 한국정밀농업학회 2023 정밀농업과학기술지 Vol.5 No.3

Precision water management is crucial for greenhouse agriculture to maximize crop yields in sandy soil. Due to the low water holding capacity, it is necessary to monitor the water movement in different depths of sandy soil to ensure effective irrigation. Therefore, this study aimed to develop a data acquisition (DAQ) system for sandy soil water content monitoring in an experimental soil bin inside a greenhouse, utilizing the capabilities of the Internet of Things (IoT). A drip irrigation system was implemented, arranged in four pipelines, spaced 60 cm apart, with drippers placed at 30 cm intervals along the pipeline. The overall system was installed in a sandy soil testing bin. A DAQ system was comprised of three basic units: sensor interfacing and circuit board, programming and sensor data acquisition, and data storage and monitoring. A microprocessor was used by interfacing a set of soil water content sensors, ambient temperature, and humidity sensors. The water content sensors were placed in the soil at different depths of 10, 20, 30, 40, and 50 cm, respectively. A microcontroller was used to collect and send the sensor data to monitor and store in memory. During the test, the maximum and minimum average of soil water content, ambient temperature, and humidity values were observed at 33.91±2.5 to 26.95±1.3%, 21.39±2.1 to 42.84±1.7°C, and 48.73±2.3 to 99.90±0.3%, respectively. The water content percentages were varied at different depths of sandy soil due to low water holding capacity. The developed automatic DAQ system would help with remote monitoring and control of greenhouse irrigation, considering the different crop characteristics and environmental conditions.

사질토의 전단거동에 실트 함량이 미치는 영향

유정석(Jeongseok Yu),안광국(Kwangkuk Ahn),강홍식(Hongsig Kang) 한국지반환경공학회 2020 한국지반환경공학회논문집 Vol.21 No.11

자연상태의 흙은 다양한 크기의 입자로 구성되어 있으며, 이 흙의 역학적 거동 중 전단거동은 입도 분포에 크게 영향을 받는다. 그리고 자연상태의 흙은 조립토와 세립토가 다양하게 혼합되어 존재하기 때문에 그 역학적 성질인 전단특성을 명확히 파악하기 어렵다. 이에 본 연구에서는 흙의 입도 분포가 흙의 전단특성에 미치는 영향을 확인하기 위한 목적으로 조립토는 모래를 세립토는 실트를 이용해 모래에 대한 실트의 함유량을 변화시켜 입도 분포가 다른 사질토를 조성한 후 링 전단시험을 수행하였다. 그리고 물 공급 시 입도 분포가 다른 사질토의 전단특성 변화를 확인하기 위해 링 전단시험 중 물을 공급하여 실험을 수행하였다. 그 결과 실트 함유량이 증가할수록 전단강도는 점차 증가하다 실트 함유량이 모래보다 많아지면 전단강도는 감소하는 것으로 나타났다. 그리고 수분 공급 시 실트 함유량에 따라 잔류전단강도는 완만한 경사를 나타내며 감소하는 것으로 나타났다. Natural soil is composed of particles of various sizes, and the shear behavior which is a kind of mechanical behavior of the soil is affected by the particle size distribution. In addition, since the natural soil contains a large mixture of coarse and fine grained soil, it is difficult to clearly understand the shear behavior of the soil. Therefore, a ring shear test was conducted on sandy soils that has various particle size distribution in order to identify the effect of the distribution on shear characteristics of soils. At this time, sand and silt were used for coarse and fine grained soils, respectively, to make sandy soils by changing the silt content. Also the water was supplied during the test to confirm shear characteristics of sandy soils with various particle size distributions. The result shows that the shear strength increases as the silt content increases, and the strength decreases as the silt content increases over the sand. Besides, residual shear strength gradually decreases because of the silt content when the water is supplied.

석고, 팽화왕겨 및 제오라이트 연속시용이 간척지 세사양토의 입단화에 미치는 영향

백승화(Seung-Hwa Baek),김재영(Jae-Young Kim),이상욱(Sang-Uk Lee),김성조(Seong-Jo Kim) 한국토양비료학회 2010 한국토양비료학회지 Vol.43 No.5

간척지 세사양토 토양에 Bermuda grass 재배 시 토양개량제의 시용이 토양 입단화도에 미치는 효과를 보기위하여 이수석고 1550 (G1), 3100 (G2), 6200 (G3) kg 10a<SUP>-1</SUP>, 팽화왕겨 1000 (H1), 2000 (H2), 3000 (H3) kg 10a<SUP>-1</SUP>, 팽화왕겨 1500 kg 10a<SUP>-1</SUP>에 zeolite를 200 (HZ1), 400 (HZ2), 800 (HZ3) kg 10a<SUP>-1</SUP>을 각각 조합처리 하는 등 3종의 토양개량제를 처리하고, 60, 90, 120 DAT(처리 후 경과 일수)에서 입단크기별 입단생성 정도를 분석하였다. 60 DAT 세사양토에서 이수석고 단일처리 효과는 G3 경우 1.0-2.0 mm의 입단이, 무처리구 보다 4.66% 감소시키고 있어서 이수석고 시용수준은 1550 kg 10a<SUP>-1</SUP>이하였다. 팽화왕겨와 팽화왕겨+zeolite는 토양의 입단 증가에 기여한 효과가 뚜렷하였다. 토양개량제별 입단생 성에 대한 효과는 팽화왕겨≥팽화왕겨+zeolite>이수석고>무처리 순이었다. 90 DAT에서 토양입단형성에 기여한 G1>G2>G3>무처리순으로 이수석고의 시용증가가 오히려 세사양토의 입단형성정도를 감소시켰다. 이때의 이수석고 시용수준도 1550 kg 10a<SUP>-1</SUP> 이하였다. 90 DAT에서 팽화왕겨처리에 의한 토양입단형성은 이수석고 처리 경우 보다 7% 이상이 높았다. 특히 2이상과 2.0-1.0 mm의 입단의 양이 높아지고 있었다. 90 DAT에서 토양의 입단형성을 위한 팽화의 시용양은 1000 kg 10a<SUP>-1</SUP> (H1) 이하였다. 팽화왕겨 1500+zeolite 200 kg 10a<SUP>-1</SUP> (HZ1) 처리구가 90 DAT에서 입단화도가 52.78%로 가장 효과적이었다. 특히 2 mm 이상과 2.0-1.0 mm의 입단이 무처리구 비하여 2-4배 높았다. 120 DAT에서 팽화왕겨 2000 kg 10a<SUP>-1</SUP> (H2)의 입단화도가 51.50%로 가장 높게 나타나고 있어 팽화왕겨처리는 입단형성 작용뿐만 아니라 입단유지에도 효과적이었다. 팽화왕겨처리 (1550 kg 10a<SUP>-1</SUP>)와 zeolite 800 kg 10a<SUP>-1</SUP>조합처리 구에서 48.51%의 입단화도를 나타내고 있었다. 결과적으로 계화도 세사양토의 입단형성 증가를 위한 토양개량제의 처리효과는 팽화왕겨>팽화왕겨+zeolite>이수석고 순이었다. We investigated influence of continious application of gypsum (G: CaSO4 ? 2H2O), popped rice hulls (H) and zeolite (Z) on soil aggregation of reclaimed sandy loam soils. The application rates amended to fine sandy loam from reclaimed soils at Kyehwado were varied as follows:1550 (G1), 3100 (G2), 6200 (G3), 1000 (H1), 2000 (H2), 3000 (H3), and 200 (HZ1), 400 (HZ2) and 800 (HZ3) added to 1500(H) kg 10a<SUP>-1</SUP>, respectively. Soil aggregates were analyzed for 60, 90 and 120 days after treatments (DAT). At 60 DAT, The amount of aggregate from soil samples treated with gypsum was slightly increased with G1 while the aggregation was decreased by 4.66% for G3 for soil aggregates than thar of control. The treatments of H or HZ were effective in soil aggregation. The effect of treatment was in the order of H > HZ > G. At 90 DAT, increasing amount of gypsum attributed to decrease in soil aggregates. Therefore, we could conclude that suitable amounts of gypsum for soil aggregation in fine sandy loam might be 1550 kg 10a<SUP>-1</SUP> or less. H1 increased aggregation by 7% for aggregate size between 1.0 and 2.0 mm. HZ1 was most effective in aggregation by 52.78% among the treatments while H2 and HZ3 51.50% and 48.51% at 120 DAT, respectively. As a result, we found that the effect of the treatment for soil amendments was in order of H > HZ > G.

불포화 사질토의 도로함몰 특성에 관한 실험적 연구

권기철 한국도로학회 2018 한국도로학회논문집 Vol.20 No.1

PURPOSES: The purpose of this study is to identify the road-subsidence mechanism in unsaturated sandy soils. METHODS: A series of soil chamber tests were conducted under various conditions. RESULTS: The cavity-expansion characteristics in unsaturated sandy soils due to seepage were affected by the outlet size, seepage intensity, relative density, and fine content. CONCLUSIONS: In unsaturated sandy soils, the cavity-expansion speed was affected by the outlet size, relative density, seepage intensity, and clay content; however, the cavity-expansion shape was very similar. As the outlet size and seepage intensity increased, the cavityexpansion speed increased. As the relative density increased, the cavity-expansion speed increased because of a sudden decrease in shear strength, resulting from the increased saturation (reduction of matric suction). The cavity expanded faster with the increasing clay content, up to a certain threshold. It expanded at a slower rate once it passed the threshold. Finally, it reached a stable state where the cavity did not expand due to seepage.

Ammonia emission from sandy loam soil amended with manure compost and urea

Adegoke Toluwase Oreoluwa,Moon Tae-il,Ku Hyun-Hwoi 한국응용생명화학회 2022 Applied Biological Chemistry (Appl Biol Chem) Vol.65 No.6

Urea is a renowned nitrogen (N) fertilizer widely used in plant N nutrition owing to its high N concentration (46%). The effect of the N application rate on ammonia ( NH3) emission into the environment and soil properties is yet to be unraveled. The rate of NH3 emission from sandy loam soil amended with manure compost (T1: 5000 kg ha− 1) and urea at different application rates (100, 200, and 400 kg N ha− 1 designated as T2, T3, and T4, respectively) with 3 replications was evaluated in an incubation experiment. Ammonia emission was rapid at the early stage of the experiment followed by an equilibrium decrease that tends toward zero at the end of the incubation. Ammonia emissions of 16.50, 52.15, and 75% of applied N in T2, T3, and T4 were observed on day 49. Ammonia emission increased linearly (y = 0.7823x−32.169, R2 = 0.95**) in response to N application rates. T1 conserves more NH4+ (20.79 mg kg− 1) in the soil, followed by T2 (11.8 mg kg− 1) and T3 (11.7 mg kg− 1). T2 and T3 reduced the soil pH to optimal for microbial activities and nutrient availability, while T4 promoted soil acidity. A balanced combination of compost and urea mitigates NH3 volatilization and improves soil fertility. In conclusion, applying compost (5000 kg ha− 1) with urea at 100 kg N ha− 1 or 200 kg N ha− 1 is recommended for NH3 volatilization mitigation, nitrification inhibition, and efficient NH4+ retention in the soil.

강성지반위 사질토층에 위치한 얕은기초의 침하량특성분석

황희석(Hwang, Hui-Seok),김동건(Kim, Dong-Geon),유남재(Yoo, Nam-Jae) 강원대학교 산업기술연구소 2014 産業技術硏究 Vol.34 No.1

In this paper the settlement characteristic of shallow foundation on sandy soil overlained by rigid ground was investigated by analyzing results of model tests. For model experiments, model tests were performed with sandy soils sampled from the field, changing the relative density of sandy soil and the ratio of thickness of sandy layer(H) to the width of model strip footing(B). As result of tests, settlement of sandy soils increases as the value of H/B increases, whereas it increases with relative density of soil. Bearing capacity decreases as the thickness of the sand layer relative to the footing width increases. In order to analyze the settlement characteristics of sandy ground, the results of model tests were compared with the predicted values using the empirical formulas proposed by Terzaghi, De Beer and Schmertmann. The method by De Beer was found to be in good agreements with test results.

직접전단시험에 의한 다양한 시료의 전단강도 특성

박춘식(Choonsik Park),정정근(Jeonggeun Jeong) 한국암반공학회 2018 터널과지하공간 Vol.28 No.6

흙의 전단강도의 적절한 기준을 제시하기 위해 모래질, 점토질, 자갈질의 약 290 여개의 재료에 대하여 직접전단시험을 수행하였다. 흙의 대분류에 의한 모래질 흙의 전단강도는 모래 함유율이 많은 흙일수록 내부마찰각은 증가하는 경향이 뚜렷하게 나타났으며, 그 범위는 23.5°~34.9°에 분포하고 있는 것으로 나타났고, 점착력은 2.0 kPa~15.7 kPa 사이에서 골고루 분포하는 것으로 나타났다. 탄성계수는 하중단계에 따라 뚜렷하게 구분할 수 있었으며, 수직하중이 증가할수록 약 80%씩 증가하였다. 점토질 흙의 내부마찰각은 15.0°~28.6°의 범위에서 점토성분 함유율이 많아질수록 감소하는 경향이 나타났고, 점착력은 일정한 범위로 증가하는 경향이 나타났다. 점토질 흙의 탄성계수는 거의 같은 증가비로 초기탄성계수만 약간 증가하는 경향을 나타내었다. 자갈질 흙의 내부마찰각은 29.9°~36.7°의 범위로 뚜렷한 특성을 파악할 수 없었다. 세부분류에 따른 SW(입도분포가 좋은 모래), SP(입도분포가 나쁜 모래), SC(점토 섞인 모래), SM(실트 섞인 모래)의 점착력은 실트함유율이 가장 많은 SM 시료에 비해 SC는 약 94%, SW는 약 78%, SP는 약 59% 정도 값을 나타내었다. 또한 내부마찰각은 ML(액성한계가 낮은 실트)과 CL(액성한계가 낮은 점토)이 거의 같은 거동 특성을 나타내었고, MH(액성한계가 높은 실트)는 ML의 약 88% 값을 나타내었다. 점착력에 대한 변화는 거의 비슷한 증가비를 나타내었다. This study conducted direct shear test on about 290 sorts of materials such as sandy soil, clayey soil and gravely soil to present proper standard on shear strength of soil. Shear strength of soil in large scale tends to show that angle of internal friction increases as sand contents grow and it ranges 23.5°~34.9° with cohesion of 2.0 kPa~15.7 kPa. Elastic modulus was visibly distinct by load, and which increased approximately 80% as vertical load grows. Angle of internal friction arranging 15.0°~28.6° on clayey soil decreased as clay contents rises and cohesion increase in regular scale. Elastic modulus tends to increase initial elastic modulus with almost same growing rate. While angle of internal friction on gravely soil indicates 29.9°~36.7° which hardly shows distinctive features. According to test in detail, cohesion of SW (well-graded sand), SP (poorly-graded sand), SC (clayey sand) and SM (silty sand) indicates value by 94%, 78% and 59% comparing to SC, SW and SP respectively. Angle of internal friction of ML (low-liquid limit silt) and CL (low-liquid limit clay) appears almost same features, and MH (high-liquid limit silt) despite of 88% value of ML. Cohesion among them varies with similar growing rate.

토성, 퇴비, 및 석회질비료 처리에 따른 튤립 구근의 생육

이봉근,유용권 한국인간·식물·환경학회 2010 인간식물환경학회지 Vol.13 No.6

본 연구는 전남 신안군 임자도에서 토성(사질토양, 밭토양, 사질토와 개펄을 혼합한 토양)과 퇴비 및 석회질 비료시비 등 토양환경에 따른 튤립 구근의 생육을 조사하여 구근생산의 기초 자료로 활용하고자 실시하였다. 'Ballerina', ‘Golden Apeldoorn', ’Kees Nelis', ‘Merry Christmas', 'Up Star' 품종 모두 밭토양에서 구근의 생육이 불량하였고, 사질토+개펄토양에서 주구의 직경, 구고, 구둘레, 구중 등 구근의 생육이 가장 양호하였다. 퇴비 처리에 있어서 'Dreaming Maid', ‘Dynasty', ‘Leen van de Mark' 품종은 무처리에 비해 퇴비를 표준량 또는 표준량의 1/2배 처리시 주구의 구고, 구둘레, 구중 등에서 양호한 생육 결과를 보여 주었다. ’Hollandia'와 ’Negrita' 품종은 전반적으로 퇴비 처리에 따라 구근 생육에는 큰 차이가 없었다. 석회질 비료처리에서 ‘Strong Gold' 품종은 무처리구에 비해 표준량 또는 표준량의 2배 처리한 것에서 구고, 구둘레 및 구중이 양호한 것으로 나타났고, ’White Dream' 품종은 표준량의 1/2배 처리에서 더 효과적인 것으로 나타났다. This study was carried out to examine the effect by treatment of soil texture(sandy soil, sandy+tidal flat soil, and up land), compost, and lime on the bulb growth in bulb production of Tulipa gesneriana cultivars in Imjado, Shinan, Jeonnam. In 'Ballerina', ‘Golden Apeldoorn', ’Kees Nelis', ‘Merry Christmas', and 'Up Star' cultivars, bulb growth, such as bulb diameter, height, circumference, and weight, was best in sandy+tidal flat soil, but was poor in up land. The compost treatment of standard fertilizing amount or 1/2 fold of standard fertilizing amount was more effective in bulb height, circumference, and weight than the other treatments in 'Dreaming Maid', ‘Dynasty', and ‘Leen van de Mark' cultivars. However, it was not different between compost treatment in ’Hollandia' and ’Negrita' cultivars. The lime treatment of standard fertilizing amount or 2 fold of standard fertilizing amount increased the bulb growth of ‘Strong Gold' cultivar. And, the lime treatment of 1/2 fold of standard fertilizing amount was effective in bulb growth of ’White Dream' cultivar.