• Title/Summary/Keyword: deep cement mixing(DCM)

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Stability Analysis of DCM treated Ground Using Centrifuge Test (원심모형시험을 이용한 DCM 처리지반의 안정성 평가)

  • Kim, Byoung-Il;Yoo, Wan-Kyu;Lee, Seung-Hyun;Han, Jin-Tae
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.3
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    • pp.105-110
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    • 2011
  • Recently, a deep mixture method as a soil improvement method of marine soft ground, which causes less noise and vibration than other methods, are widely used. In this study, for DCM(Deep Cement Mixing) method, one of the deep mixture method, optimum mixing ratio of clay-cement was suggested using uniaxial compression tests on specimens with various mixing ratio of claycement. In addition, the stability of a caisson on tangent circle-type and wall-type DCM treated ground was evaluated using centrifuge tests. As a result, optimum mixing ratio of clay-cement was 28.5% and the stability of the caisson on DCM treated ground was confirmed. However, the lateral displacement of the caisson on the wall-type DCM treated ground was 7% less and the settlement of that was 39% less than the case of the tangent-circle-type DCM method.

Application for Self-Supported Retaining Wall Using Deep Cement Mixing (DCM(심층혼합처리공법)에 의한 자립식 흙막이 적용사례)

  • Jeong, Gyeong-Hwan;Kim, Yong-Wan;Shin, Min-Sik;Han, Kyoung-Tae;Kim, Tae-Hyo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.257-267
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    • 2006
  • The earth retaining wall systems for excavation works in a populated urban area or a poor soil deposit can be limited due to various restriction. Thus there are various methods to be applied for them such as the soldier pile method, the diaphragm wall with counterfort and so on. In this study, the self-supported earth retaining wall using the DCM(Deep Cement Mixing) method, including its merits, demerits and some important characteristics occured in the design and the construction stage, was introduced. It might be reference for the other design and construction procedures using the DCM method.

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Case Study of Stress Concentration Ratio of Composite Ground Improved by Deep Cement Mixing Method (심층혼합처리공법으로 개량된 복합지반의 응력분담비에 대한 사례 연구)

  • Yoo, Wan-Kyu;Kim, Byoung-Il;Kim, Young-Uk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.7
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    • pp.3216-3223
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    • 2012
  • Deep cement mixing method (DCM) is one of the most effective improving methods for deep soft ground. The strength of soft soil can be increased in a short period of time with less noise and vibration. However, it is necessary to determine the stress transferring and concentration ratio of the composite soft ground for estimating the settlement behaviors. In this study, a model test was undertaken to investigate the stress distribution of the improved soil. Results of the model test shows that stresses were concentrated mainly on the improved areas by DCM and the concentration ratios (35.4, 28.6, 27.02) were obtained using several different techniques. These were well in accordance with other previous research results (26.52, 32.5).

Forensic Engineering Study on Structure Stability Evaluation of Deep Cement Mixing Vessel using ADINA Software (ADINA 를 이용한 DCM 선박의 구조안정성 평가에 관한 연구)

  • Kim, Eui Soo;Kim, Jong Hyuk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.11
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    • pp.1283-1290
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    • 2014
  • Recently, a wide variety of simulation techniques such as structure analysis and structure-fluid interaction analysis are being employed in the field of forensic engineering for resolving the problem of legal liability for accidents and disasters. In this study, we performed a forensic engineering investigation of a sinking accident of a DCM (deep cement mixing) vessel. The accident vessel was built as a dedicated SCP (sand compaction pile) vessel at the time of vessel building, and the DCM vessel was structurally modified, e.g., by increasing the leader height and constructing for leader expansion, without a stability review. To determine the effects of expansion and modification of structures in this sinking accident, structural stability evaluation was performed using commercial software for structural analysis, ADINA software. Through an analysis and comparison of simulation results obtained using ADINA software with the results of the structural modification and expansion, we could determine the exact cause of the sinking accident of the DCM vessel.

Application to Breakwater Foundation by DCM (DCM 공법에 의한 방파제 기초 적용사례)

  • Gu, Im-Sik;Kim, Young-Sang;Jeong, Gyeong-Hwan;Choi, Jeong-Uk;Shin, Min-Sik;Kim, Jae-Hyon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.372-382
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    • 2006
  • The DCM(Deep Cement Mixing) Method was introduced domestically in 1985 and has been applied widely to improve stability, increase bearing capacity and reduce settlement of the structure. It has been only performed by the combined equipment to improve the soft ground in coastal areas. But it has qualify-control problems such as interference of waves and improving depth, etc. Therefore DCM Barge of specialist equipment, named by Dong Ji Ho, was equipped with three mixing shafts with four rod and installed GPS system In itself, had been developed in 2005 for the purpose of solving the above problems. This paper represents about Dong Ji Ho's qualify-control system as well as it's first domestic application to in-situ trial test and the original design of the Ulsan breakwater site.

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Integrity Test of DCM Treated Soils with a Cross-hole Sonic Logging (시추공간 음파검층법을 이용한 심층혼합 개량지반의 건전도 조사)

  • 김진후;조성경
    • Journal of Ocean Engineering and Technology
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    • v.15 no.1
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    • pp.73-78
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    • 2001
  • Soundness evaluation of a structure being constructed under the sea is usually difficult. In this study, a cross-hole sonic logging(CSL) which have been used for non-destructive test of concrete piles is adopted for the integrity test and monitoring of DCM(deep cement mixing) treated soils. Chemical and physical characteristics of raw ground materials are analysed to delineate ground environmental effects on the strength of DCM treated soils. In order to convert cross-hole sonic logging data into compressive strength, correlations between compressive strengths and wave velocities of core samples have been obtained. It is found that there is little effect of ground environment on the strength of the DCM treated soils, and the density distribution of core samples and cross-hole logging data show that a defective zone may exist in the DCM treated soils. With the time lapse, however, the defective zone has been cured and consequently, compressive strength of the DCM treated soils increases and satisfies the design parameter. From this study it can be concluded that the cross-hole sonic logging can be used for the integrity test as well as monitoring the curing stage of the structures, successfully.

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Effects of DCM Column Properties in Softground on Stabilities of Underground Roadways (연약지반내 DCM 개량체의 특성이 지하차도의 안정성에 미치는 영향)

  • Ahn, Tae-Bong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.2C
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    • pp.77-84
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    • 2010
  • In planning underground roadway foundation on soft ground, deep cement mixing method (DCM) is employed. The proper mixing ratio using batch test and replacement rates that meet strength criteria are used for deep cement mixing column. Stiffness ratio and distance between deep cement mixing columns (C.T.C) are varied to find out influences on stress, displacement, and differential settlement. The replacement ratios that meet settlement criteria are 10~35%. As stiffness varies, stress reaches at 769.kPa that exceed criteria due to stress concentration when stiffness ratio difference is over 30. Also, when C.T.C is 5 m, stress spreads to soils, so C.T.C need to be considered carefully. The vertical displacement is 0.6~1.56 cm, and angular distortion is 1/909~1/510.

Case Studies of Penetration Characteristics of DCM Wall Using Spiral Mixing Blades in Soil Layers (특수교반날개를 사용한 DCM 공법의 지반 관입 특성에 대한 사례연구)

  • Jung, Doo-Hoi;Jeong, Gyung-Hwan;Yang, Tae-Seon
    • Journal of the Korean Geotechnical Society
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    • v.23 no.3
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    • pp.133-140
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    • 2007
  • DCM (Deep Cement Mixing Method) has been applied to build structures such as self-supported earth retaining walls. DCM columns should be penetrability into the stiff layer to assure the self-supporting ability. On the penetration increase of blade attached to the DCM mixing tools, a spiral mixing blade has been revised. Penetration characteristics of spiral blades in the stiff soil layer were evaluated through Gimhae and Incheon areas. The spiral mixing blades could penetrate into the stiff soil layers which have the N-value of greater than 30 although the penetration rate is somewhat slow. Penetration characteristics and economical efficiency should be discussed to determine the critical depth of the spiral mixing blade because the penetration efficiency can decrease in the stiff layer in this paper.

A Case Study on the High-quality DCM applied to the Foundation of Breakwater (방파제 기초에 적용된 고품질 DCM공법의 설계 및 시공 사례)

  • Kang, Yeoun-Ike;Shim, Min-Bo;Shim, Sung-Hyun;Kim, Ha-Young;Shim, Jae-Bum;Chun, Youn-Chul;Yoon, Jung-Ik
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.815-826
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    • 2009
  • The paper presents a case study addressing the design and construction aspects for DCM(Deep Cement Mixing) method employed as the foundation of a caisson type breakwater with heavy weight(10,700 ton/EA) and a high design wave height($H_{1/3}$=8.7m). The DCM was designed for the project(Ulsan New Port North Breakwater Phase 1) by optimizing the pattern of DCM columns with a combination of short and long columns (i.e., block type(upper 3m)+wall type(lower)) and considering overlapped section between columns as a critical section against shear force where the coefficient of effective width of treated column($\alpha$) was estimated with caution. It was shown that the value can be 0.9 under the condition with the overlapped width of 30cm. In addition to that, a field trial test was performed after improving conventional DCM equipment (e.g., mixing blades, cement paste supplying pipes, multi auger motor, etc.) to establish a standardized DCM construction cycle (withdrawal rate of mixing blades) which can provide the prescribed strength. The result of the field strength test for cored DCM specimens shows that the averaged strength is larger than the target strength and the distribution of the strength(with a defect rate of 7%) also satisfies with the quality control normal distribution curve which allows defect rate of 15.9%.

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Application of Artificial Neural Network Theory for Evaluation of Unconfined Compression Strength of Deep Cement Mixing Treated Soil (심층혼합처리된 개량토의 일축압축강도 추정을 위한 인공신경망의 적용)

  • Kim, Young-Sang;Jeong, Hyun-Chel;Huh, Jung-Won;Jeong, Gyeong-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1159-1164
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    • 2006
  • In this paper an artificial neural network model is developed to estimate the unconfined compression strength of Deep Cement Mixing(DCM) treated soil. A database which consists of a number of unconfined compression test result compiled from 9 clay sites is used to train and test of the artificial neural network model. Developed neural network model requires water content of soil, unit weight of soil, passing percent of #200 sieve, weight of cement, w-c ratio as input variables. It is found that the developed artificial neural network model can predict more precise and reliable unconfined compression strength than the conventional empirical models.

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