• Title/Summary/Keyword: retaining wall

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A Study on the Utilization Method in the SCW Method using Supplementary Cementitious Materials (시멘트 대체재료를 활용한 SCW공법에서의 활용 방안에 대한 연구)

  • Kwang-Wu Lee;Jae-Hyun Park;Young-Won Lee;Dae-Sung Cho
    • Journal of the Korean Geosynthetics Society
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    • v.22 no.3
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    • pp.87-95
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    • 2023
  • Recently, redevelopment of the original downtown area is underway, the necessity of construction in adjacent location is increasing. However, excavations in dense urban areas are prone to ground problems due to various causes, so it is necessary to use materials and methods that can minimize such problems. As a general earth retaining method, various methods such as diaphragm wall and CIP method are applied using cement. However, since a large amount of cement is used for the installation of earth retaining method, it is necessary to conduct research on the development of new cement substitute materials to significantly reduce greenhouse gas emissions. In this study, we utilized the hardening reaction of blast furnace slag powder, desulfurized gypsum and high calcium fly ash by alkali activation and applied it to the SCW method. As a result, it was analyzed that the compressive strength of solidified soil using development solidification material was 96.2 ~ 106.3% of OPC at 28 days of curing. In addition, the strength increment ratio was 2.06 for sandy soil and 2.41 for clayey soil, which was higher than 1.85 of OPC. It seems an advantageous in terms of long-term strength. In addition, from the environmental point of view, it was analyzed that there is no elution of heavy metals and that greenhouse gas emissions can be dramatically reduced. Therefore, if further studies are conducted, it can be applied to the SCW method.

A Study on Imposing Exact Solutions as Internal Boundary Conditions in Simulating Shallow-water Flows over a Step (계단을 지나는 천수 흐름의 모의에서 내부 경계조건으로서 정확해의 부여에 관한 연구)

  • Hwang, Seung-Yong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.2
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    • pp.479-492
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    • 2014
  • In this study, was proposed a numerical scheme imposing exact solutions as the internal boundary conditions for the shallow-water flows over a discontinuous transverse structure such as a step. The HLLL approximate Riemann solver with the MUSCL was used for the test of the proposed scheme. Very good agreement was obtained between simulations and exact solutions for various problems of the shallow-water flows over a step. In addition, results by the numerical model showed good agreement with those of dam-break experiments over a step and stepped chute one. Developed model can simulate the shallow-water flows over discontinuous bottom such as a drop structure without additional rating curve or topography smoothing. Given the proper evaluations for the flow resistance by a step and the energy loss by the nappe flow in the future, could be simulated flooding and drying of the shallow-water flows over discontinuous topography such as a weir or the river road with retaining wall.

A Case Study on the Top-Down Methods Performed in the Excavation Works of Domestic Downtown (국내 도심지 굴착공사에 적용된 Top-Down 공법의 시공사례 연구)

  • Chung, Jeeseung;Park, Sukk
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.2
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    • pp.5-19
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    • 2017
  • Underground excavation for building construction in Korea is changing from conventional support method (Strut, Ground anchor) to inside permanent support method by stability, economic, circumstances around excavation and etc. This study was selected the sites of Top-down, New Top-down, S.P.S, S.T.D and B.R.D in general use. This study was compared and analyzed a construction cost and period between aforementioned methods and conventional support method. Also, this study was confirmed the stability of temporary retaining wall by analysis for measurement data under construction. As a result, this study can grasp that most improved permanent support method is excellent in economic and constructability than conventional support method in case of deep excavation and rapid appearance of bedrock.

Evaluation of Pile Spacing Ratio of Stabilizing Piles for Ground Destruction Reduction at the Time of Soft Ground Excavation (연약지반 굴착시 지반파괴 저감을 위한 억지말뚝의 간격비 평가)

  • Kim, Jae-Hong
    • Journal of the Korean Geotechnical Society
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    • v.32 no.7
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    • pp.47-56
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    • 2016
  • In the case of excavating ground backfilled with soft ground, ground destruction occurs owing to the discharge of groundwater from excavated back ground in spite of earth retaining wall. To minimize this, indoor model test was implemented applying stabilizing pile as a solution for ground destruction. The unreinforced case was compared with the reinforced case and the comparison demonstrated that the ratio of the gap in settlement of the two cases is about three to one, which proves the reinforcement effect (Kim, 2014). This study has carried out the evaluation of appropriate pile spacing ratio, according to the confirmed effect of stabilizing pile. In the evaluation test the case with pile spacing ratio of 0.66 (5 stabilizing piles) was compared with that of 0.76 (3 stabilizing piles), and it has been shown that applying stabilizing pile has effect on ground destruction reduction, but may rather work as load when pile spacing ratio is narrower than a certain interval. So it was found that adjustment for appropriate pile spacing ratio is required at the stage of design. This study has shown that the pile spacing ratio is appropriate at around 0.7~0.8, which reduces ground destruction and does not function as the load of excavated back ground.

Modelling of Permeability Reduction of Soil Filters due to Clogging (흙 필터재의 폐색으로 인한 투수성 저하 모델 개발)

  • ;;Reddi, Lakshmi.N
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.10a
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    • pp.271-278
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    • 1999
  • Soil filters are commonly used to protect the soil structures from eroding and piping. When filters are clogged by fine particles which are progressively accumulated, these may lead to buildup of excessive pore pressures also leading to instability in subsurface infrastructure. A filter in the backfill of a retaining wall, a filter adjacent to the lining of a tunnel, or a filter in the bottom of an earth dam can be clogged by transported fine particles. This causes reduction in the permeability, which in turn may lead to intolerable decreases in their drainage capacity. In this thesis, the extent of this reduction is addressed using results from both experimental and theoretical investigations. In the experimental phase, the permeability reduction of a filter is monitored when an influent of constant concentration flows into the filter (uncoupled test), and when the water flow through the soil-filter system to simulate an in-situ condition (coupled test), respectively. The results of coupled and uncoupled test are compared with among others. In the theoretical phase of the investigation, a representative elemental volume of the soil filter was modeled as an ensemble of capillary tubes and the permeability reduction due to physical clogging was simulated using basic principles of flow in cylindrical tubes. In general, it was found that the permeability was reduced by at least one order of magnitude, and that the results from the uncoupled test and theoretical investigations were in good agreement. It is observed that the amount of deposited particles of the coupled test matches fairly well with that of the uncoupled test, which indicates that the prediction of permeability reduction is possible by preforming the uncoupled test instead of the coupled test, and/or by utilizing the theoretical model.

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Reliability Analysis and Utilization of BIM-based Highway Construction Output Volume (BIM기반 고속도로 공사 물량산출 신뢰성 검토 및 활용)

  • Jung, Guk-Young;Woo, Jeong-Won;Kang, Kyeong-Don;Shin, Jae-Choul
    • Journal of KIBIM
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    • v.3 no.3
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    • pp.9-18
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    • 2013
  • In case of applying the BIM method in the civil engineering of irregularly shaped structure, BIM method began to be introduced in the current building engineering area compared with the expected effects of the relatively high construction productivity has been recognized. In this paper, I have developed quantity calculation algorithms applying it to earthwork and bridge construction, tunnel construction, retaining wall construction, culvert construction and implemented BIM based 3D-BIM Modeling quantity calculation. Structure work in which errors occurred in range between -6.28% ~ 5.17%. Especially, understanding of the problem and improvement of the existing 2D-CAD based of quantity calculation through rock type quantity calculation error in range of -14.36% ~ 13.07% of earthwork quantity calculation. It's benefit and applicability of BIM method in civil engineering. In addition, routine method for quantity of earthwork has the same error tolerance negligible for that of structure work. But, rock type's quantity calculated as the error appears significantly to the reliability of 2D-based volume calculation shows that the problem could be. Through the estimating quantity of earthwork based 3D-BIM, proposed method has better reliability than routine method. BIM, as well as the design, construction, maintenance levels of information when you consider the benefits of integration, the introduction of BIM design in civil engineering and the possibility of applying for the effectiveness was confirmed. In addition, as the beginning phase of information integration, quantity document automation program has been developed for activation of BIM. And automatically enter the program code number, linkage and manual volume calculation program, quantity document automation programs, such as the development is now underway, and step-by-step procedures and methods are presented.

Analysis on the Long-Term Shoreline Changes for Beaches Near Bangpo Port Using Aerial Imagery (항공사진을 이용한 방포항 인근 해빈의 장기간 해안선 변화 분석)

  • Kim, Baeck-Oon;Yun, Kong-Hyun;Lee, Chang-Kyung
    • Korean Journal of Remote Sensing
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    • v.29 no.5
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    • pp.477-486
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    • 2013
  • To analyze tendency of temporal and spatial change of shorelines and to estimate rate of shoreline changes using long-term shoreline change data is very important for the coastal environmental management. In this study, investigation was conducted to estimate the rate of shoreline changes using long-term shoreline change data from the year 1985 to 2009 aerial photographs. In this process aerial triangulation, GPS surveying and digital mapping was done for the estimation of changes. As the results, shorelines of Bangpo and Kkotji Beach retreated at a maximum rate of 0.2 m/yr and 0.8 m/yr, respectively. The shoreline could be changed by various factors. However, it was presumed that coastal erosion has been mainly affected by retaining wall constructed in the late 1990s.

Design of a Smart Safety Measurement System Using Bluetooth Beacon Sensor Nodes (블루투스 비콘 센서 노드를 활용한 스마트 안전 계측 시스템 설계)

  • Park, Young-soo;Park, Chang-jin;Cho, Sun-hee;Park, Kyoung-yong;Kim, Min-sun;Seo, Jeongwook
    • Journal of Advanced Navigation Technology
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    • v.21 no.1
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    • pp.126-131
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    • 2017
  • This paper designs a smart safety measurement system with Bluetooth beacon sensor nodes that can provide risk detection and evacuation/countermeasure services. The Bluetooth beacon sensor nodes is easily able to be attached to old building wall or construction or civil structure with potential danger. The proposed smart safety measurement system transmits various sensor data such as acceleration, gyroscope, geomagnetic, pressure, altitude, temperature, humidity at the spot where Bluetooth beacon sensor nodes are installed, and we can use them for risk perception, prediction, and warning services. To verify the effectiveness of the proposed system, we performed filed tests which showed that measured displacement values of precast retaining walls were within the permitted displacement value of 38.5 mm.

The Structural Characteristics of the Temporary Cofferdam in Accordance with the Shape and Size Obtained from Numerical Analysis (유한요소 해석을 통한 형상 및 크기에 따른 가물막이 특성 검토)

  • Kim, Hyun-Joo;Choi, Jin-O;Gwon, Yun-Ho
    • Journal of the Korean Geotechnical Society
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    • v.36 no.1
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    • pp.29-38
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    • 2020
  • These days the circular cross section cofferdam has been frequently used for the earth retaining structures or cut off wall such as ventilating opening, intake tower in cofferdam, shaft for emergency. By the arching effect, the circular cross section type cofferdam has more advantage than a polygon cofferdam in terms of the structural forces and moment. This paper shows the proper approach to analyze the circular cross section cofferdam using 2D Finite Element Method (FEM) for the circular stiffener (ring beam) evaluation. Besides, the various shapes of cofferdam indluding circular cross section have modeled the 3D Finite Element Mothod (FEM). The circular cross section cofferdam shows the minimum reaction force compared with the other shapes of cofferdam.

Pullout Characteristics of Geogrid with Attached Passive Reinforcement (마찰돌기를 부착한 지오그리드의 인발특성 평가)

  • Moon, Hongduk;Yoo, Chulho
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.11
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    • pp.43-51
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    • 2014
  • In this study, a series of pullout experiments were conducted on geogrid with attached passive reinforcement with respect to silt containments. Experiments were performed on man-made sand ground containing different silt of 0 %, 17 %, 35 % under various normal stresses 30 kPa, 60 kPa, 120 kPa respectively. The pullout test results showed that passive reinforcement increased the pullout strength over all silt contained condition and showed up to 20 % increases for same soil condition. The test results converted to the coefficient of interaction of pullout test to investigate the effect of reinforcement and the case of passive reinforcement showed 0.7~1.6 distribution depend on a silt contents. Therefore it is concluded that the overall length of geogrid can be reduced under the low vertical stress conditions.