• Title/Summary/Keyword: soil penetration resistance

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A Study on Vibratory Behavior of Steel Sheet Pile Installed in Sand Ground (모래지반에 대한 강널말뚝의 진통항타거동 연구)

  • Lee, Seung-Hyun;Lee, Jong-Ku;Yoo, Wan-Kyu;Kim, Byoung-Il
    • Journal of the Korean Geotechnical Society
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    • v.23 no.4
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    • pp.79-90
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    • 2007
  • Behaviors of instrumented steel sheet piles which are installed in sand ground by vibratory hammer were investigated. Especially, stresses acting on the pile during vibratory driving, efficiency factor which reflects differences between theoretical driving force and actually delivered acting force, justifiability of rigidity of steel sheet pile, dynamic resistance characteristics of soil and penetration characteristics of sheet pile were analysed. According to the field test results it is justifiable that steel sheet pile behaves as a rigid body during vibratory driving. And it can be seen that maximum stress acting on sheet pile section is far less than tensile strength of the material. Value of the maximum section force at sheet pile head was 72% of that estimated from theoretical equation. Magnitudes of displacement amplitudes computed from displacement-time history curve corresponding to four penetration depths were in the range of 16 $\sim$ 75% of that specified by manufacturer.

Estimation of Undrained Shear Strength for Clays Using Effective Cone Factor (유효콘계수를 이용한 포화점토의 비배수전단강도 평가)

  • Kim, Chang-Dong;Kim, Soo-Il;Lee, Jun-Hwan
    • Journal of the Korean Geotechnical Society
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    • v.24 no.11
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    • pp.133-141
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    • 2008
  • In this study, a new method for estimating the undrained shear strength $s_u$ of saturated clays using piezocone penetration test (CPTu) result is proposed. This is to develop more effective CPTu-based $s_u$ estimation method at lower cost with less uncertainty. For this purpose, a marine clay deposit is selected and tested through extensive experimental testing program including both in-situ and fundamental laboratory tests. The proposed method is based on a correlation between the undrained shear strength $s_u$ and the cone resistance $q_t$, without introduction of the total overburden stress into the $s_u-q_t$ correlation. As a result, no additional testing procedure for collecting undisturbed soils samples is required, which can reduce overall testing cost. To verify the proposed method, 4 test sites, which consist of a variety of soil conditions, are selected and used for comparison between measured and predicted undrained shear strength. From comparison, it is seen that predicted values of $s_u$ using the proposed method match well those from measured results.

Effects of Nutrient Source on Soil Physical, Chemical, and Microbial Properties in an Organic Pear Orchard (유기질 비료 급원이 배 과원의 토양 물리화학성 및 미생물성에 미치는 영향)

  • Choi, Hyun-Sug;Li, Xiong;Kim, Wol-Soo;Lee, Youn
    • Korean Journal of Environmental Agriculture
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    • v.30 no.1
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    • pp.16-23
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    • 2011
  • BACKGROUND: This study was conducted to investigate the effects of different organic treatments and a chemical fertilizer on the soil chemical, physical, and microbial properties in an organic pear orchard. METHODS AND RESULTS: Control was referred as a NPK chemical fertilizer (15N-9P-10K) and organic treatments included compost containing with oil cake, compost containing with humic acid, and compost containing with chitin substance. All treatments applied at rates equivalent to 200 g N per tree per year under the tree canopy in March 30 of 2008 and 2009. Soil bulk density, solid phase, liquid phase, and penetration resistance were not significantly different among the treatments. Organic treatment plots had greater organic matter, total nitrogen, potassium, and magnesium concentrations compared to control, and the nutrient concentrations were not consistently affected by the organic treatments. Microbial biomass nitrogen and carbon, dehydrogenase, acid-phosphatase, and chitinase activities overall increased from March to August. Organic treatments, especially compost containing with oil cake or chitin aicd, increased the microbial variables compared to control. CONCLUSION(s): All the organic treatments consistently stimulated soil biological activity. The consistent treatment effect, however, did not occur on the soil mineral nutrition as the trees actively taken up the nutrients during a growing season, which would have diminished treatment effects. Long-term study required for evaluating soil physical properties in a pear orchard.

A Study on the Liquefaction Potential Evaluation of Reclaimed Land Using Laboratory Test and Field Tests (현장 및 실내시험을 이용한 준설매립지반의 액상화 평가에 관한 연구)

  • Kim, Jong-Kook;Chae, Young-Su
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.1528-1537
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    • 2005
  • The purpose of this study is investigated the method for estimation of the liquefaction on the reclaimed land, located in Incheon and assessed the ability of liquefaction under the condition of criteria, which is the magnitude '6.5' of seismic on the basis of the domestic seismic characteristics. Performed not only field test but the experiment as well to study how the fine content would affect into the dreging and reclaimed land and also estimated the safety factor through the empirical method and anticipated detail method based on the results. Within the reclaimed land, there are many sized soils which are almost extended from well-graded silty sand(SM) to poor-graded fine grained sand, and which have the condition, so called, the liquefaction which is easily to bring into under the circumstances within the ground. However, partly, now that the soil is mixed with silt and silty clay which include the content of fine grained dust quite a bit, the difficulties and inconveniences has been expected while trying to find the ratio of cyclic resistance, but finally Seed and Idriss method showed the most way when we estimate the safety factor on the liquefaction.

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Evaluation of the Low Replacement Reinforced Ground Using Laboratory Tests (실내시험을 이용한 저치환 보강지반의 평가)

  • Bae, Woo-Seok
    • Journal of the Korean Society of Safety
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    • v.23 no.6
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    • pp.131-137
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    • 2008
  • SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.

Effects of Soil Compaction upon the Vegetation Environment around the Trails in Pukhansan National Park (북한산(北漢山) 국립공원(國立公園)의 등산로(登山路) 주변(周邊)에서 답압(踏壓)이 식생환경(植生環境)에 미치는 영향(影響))

  • Suh, Min Hwan;Lee, Don Koo
    • Journal of Korean Society of Forest Science
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    • v.76 no.2
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    • pp.127-137
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    • 1987
  • This study was conducted to examine the effects of trampling on the changes in soil and vegetation around the trails. The study areas were established both on the trails and in the forested areas located in Ui and Jeongnung valleys at Pukhansan National Park. Soil core sampling, measurements of vegetations and counts of persons visited per hour were done during the period from April 6 to October 9, 1986. The physical properties of soils became better with increasing distances from the trail, and the best conditions were observed in the forested areas. The differences were not significant among the zones within the trailside. More number of individuals and basal area (or coverage) in woody plants were observed in the forested areas than at trailsides. For the herb layer, however, more number of individuals and coverage were shown at the trailside. In the Ui valley, the quantitative measures of herbaceous plants decreased as the bulk density and penetration resistance increased. In the Jeongnung valley, however, only bulk density was negatively related to the quantitative measures. The fact that there were poor relations between soil factors and quantitative measures of herbaceous plants in Jeongnung valley might be influenced by other factors rather than soil compaction. Thus, more research would be needed to understand the critical factors affecting the vegetational changes in recreation areas.

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Variation of Soil Properties by Permeating Injection of Chemical Grouts (약액(藥液)의 침투주입(浸透注入)에 의한 토질성상변화(土質性狀變化))

  • Chun, Byung Sik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.2 no.4
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    • pp.1-9
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    • 1982
  • Variation of soil properties is studied by permeating injection of chemical grouts, such as cement type, water-glass type and acrylamide type, to the same soil samples with different densities. Moreover, injection tests using specially prepared equipments of 1.0 shot system and 1. 5 shot system are attempted to investigate permeating injection effects in highly compacted soil and in the presence of ground water. The main factor which causes the improvement of cut-off effect and shearing strength is the cohesion of soil. The strength in the loose state is fundamentally governed by the membrane cohesion, meanwhile, in the loose state is governed by the structural cohesion. Injection effects under the ground water flow is considerably decreased, and effective gelling ratio of approximate 45~80% is observed by variation of velocity and gel time, besides grading of injection materials has high relation with permeation and traveling length but has little relation with effective gelling ratio. Permeating injection effects, such as gelling scope, gelling strength in highly compaoted soil conditions can be confirmed by penetration resistance diagram and iso-strength curve.

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Soil Depth Information DB Construction Methods for Liquefaction Assessment (액상화 평가를 위한 지층심도DB 구축 방안)

  • Gang, ByeongJu;Hwang, Bumsik;Kim, Hansam;Cho, Wanjei
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.3
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    • pp.39-46
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    • 2019
  • The liquefaction is a phenomenon that the effective stress becomes zero due to the rapidly accumulated excess pore water pressure when a strong load acts on the ground for a short period of time, such as an earthquake or pile driving, resulting in the loss of the shear strength of the ground. Since the Geongju and Pohang earthquake, liquefaction brought increasing domestic attention. This liquefaction can be assessed mainly through the semi-empirical procedures proposed by Seed and Idriss (1982) and the liquefaction risk based on the penetration resistance obtained from borehole DB and SPT. However, the geotechnical information data obtained by the in-situ tests or boring information fundamentally have an issue of the representative of the target area. Therefore, this study sought to construct a ground information database by classifying and reviewing the ground information required for liquefaction assessment, and tried to solve the representative problem of the soil layer that is subject to liquefaction evaluation by performing spatial interpolation using GIS.

Study on the Vertical Pile Capacity of Base-grouted Pile (선단 하부지반 그라우팅된 개단강관말뚝의 연직 지지력에 관한 연구)

  • 정두환;최용규;정성교
    • Journal of the Korean Geotechnical Society
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    • v.15 no.2
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    • pp.165-180
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    • 1999
  • Static load tests were performed for open-ended piles, closed-ended piles, piles with grouted toe, and base-grouted piles by using calibration chamber. Then vertical bearing capacities determined from load tests were compared with each other. The stability of base-grouted pile during a simulated seaquake was investigated by changing the penetration depth. Also, static load tests and seaquake tests for 2-piles and 4-piles group were performed. The bearing capacity of the pile grouted inside the toe was 11.2~30.8% less than that of open-ended pile because of reduction of base resistance due to disturbance of base soil under pile toe. The bearing capacity of a base-grouted pile was 23.8~33.9% more than that of an open-ended pile and was similar to that of a closed-ended pile. The bearing capacity of base-grouted group pile was increased ; the bearing capacity of base-grouted 2-piles group increased 14.6~31.8% compared to that of open-ended 2-piles group, and that of base-grouted 4-piles group increased 15.3~22.4% compared to that of open-ended 4-piles group. During the simulated seaquake in deep sea, stability of base-grouted pile was found to be dependent on the pile penetration depth. During seaquake motion, single long base-grouted pile longer than 20m was stable and short base-grouted pile shorter than 12m failed. But relatively long base-grouted pile longer than 12m kept mobility state. Bearing capacity of base-grouted group pile with penetration depth less than 7m was degraded a little bit ; so, base-grouted group pile could maintain mobility condition.

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Studies on Amelioration of Soil Physico-Chemical Properties and Rice Yield in Sandy Tidal Saline Paddy Soil (사질(砂質) 염해답(鹽害畓)에서 개량제(改良劑) 시용(施用)이 토양(土壤)의 물리화학성(物理化學性) 변화(變化)와 수도수량(水稻收量)에 미친 영향(影響))

  • Yoo, Chul-Hyun;Kim, Jong-Gu;Choi, Song-Yeol;Cho, Guk-Hyun;Yoo, Sug-Jong;So, Jae-Dong;Rhee, Gyeong-Soo
    • Korean Journal of Soil Science and Fertilizer
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    • v.26 no.4
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    • pp.241-248
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    • 1993
  • An experiment was conducted in 1990~1991 to study the effects of various soil amelioration on the soil productivity and machine workability at tidal land paddy field of Kyewhado Substation, Homam Crop Experiment Station. The soil, Munpo Series(fine sandy loam, Typic Fluvaquents) was treated with gipsum, rice straw, rice straw compost and foreign soil(at 20cm depth) after deep ploughing. The results are surmerized as follows. 1. Sand and clay were slightly increased, while silt was slightly decreased in the rice straw and compost plots. The soil texture was changed from loam to sand loam by the addition of foreign soil 2. Soil bulk density and porosity was decreased in the rice straw, compost and foreign soil addition plots. 3. Cone penetration resistance was $12.5kg/cm^2$ at 10cm of soil depth before experiment and $12.5kg/cm^2$ at 20cm of soil depth after experiment except control, and the root zone was expended down to 20cm. 4. Soil salt content before experiment was 0.46 and 0.48% for surface soil(10cm) and subsoil(20cm), respectively ; The salt content of ameliorated plot was 0.26~0.32% and 0.16~0.31%, respectively, indicating good leaching of soil salt by the soil improvements. 5. The yields of rice in different treatments were in the order of the foreign soil addition > compost > gypsum > rice straw > control.

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