• Title/Summary/Keyword: 흙막이공

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Effects of Functional Improvement of Multiaxis Flat Continuous Soil Cement Earth Retaining Wall (다축 평면 연속형 SCW 흙막이 벽체의 개선 효과)

  • Chung, Choong-Sub;Yoo, Chan Ho;Nam, Ho Seong;Choi, In Gyu;Baek, Seung Cheol
    • Journal of the Korean Geotechnical Society
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    • v.39 no.11
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    • pp.7-22
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    • 2023
  • In January 2022, a new legislation was enforced to enhance the safety of underground construction. Consequently, a comprehensive assessment of underground safety is now an integral part of the planning process, including an evaluation of its impact. Ensuring the stability of temporary retaining walls during underground excavation has become paramount, prompting a heightened focus on the assessment of underground safety. This study delves into the analysis of the Multi-axis Flat Continuous Soil Cement Wall retaining wall (MFS) construction method. This method facilitates the expansion of wall thickness in the ground and provides flexibility in selecting and spacing H-piles. Through laboratory model tests, we scrutinized the load-displacement behavior of the wall, varying the H-pile installation intervals using the MFS method. Additionally, a 3-dimensional numerical analysis was conducted to explore the influence of H-pile installation intervals and sizes on the load for different thicknesses of the MFS retaining wall. The displacement analysis yielded the calculation of the height of the arching effect acting on the wall. To further our understanding, a design method was introduced, quantitatively analyzing the results of axial force and shear force acting on the wall. This involved applying the maximum arching height, calculated by the MFS method, to the existing member force review method. The axial force and shear force, contingent on the H-pile installation interval and size applied to the MFS retaining wall, demonstrated a reduction effect ranging from 24.6% to 62.9%.

Behavior of the Ground under a Building due to Adjacent Ground Excavation (근접굴착시 건물 하부 지반의 거동)

  • Lee, Jong-Min
    • Journal of the Korean Geotechnical Society
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    • v.34 no.4
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    • pp.49-55
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    • 2018
  • A pre-load of bracing was imposed to prevent the horizontal displacement on the strut of the braced wall adjacent to the building during the ground excavation. For this purpose, large scale model tests were conducted, without and with pre-load on braced wall. Adjacent building load was also imposed in different locations, that were 0 m, 1D, 2D on ground surface. In this study, model tests in 1:10 scale were performed in real construction sequences, and adjacent building was 12 m in width and the size of model test pit was 2 m in width, 6 m in height, and 4 m in length. As a result, it was found that the stability of the existing building adjacent to the braced wall within Rankine's active zone could be greatly enhanced when the horizontal displacement of the braced wall was reduced by applying a pre-load. which was larger than the designated axial force on the strut of the braced wall.

An Experimental Investigation for the Effects of Pre-loading on the Ground Movement in Sand (선행하중 적용시 흙막이 벽체 및 주변지반의 거동에 관한 굴착모형실험)

  • 이봉열;김학문
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.15-26
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    • 2003
  • Urban excavation requires highly reliable prediction technique for the design and construction of earth retaining structure in order to protect adjacent structures around deep excavation. Application of the pre-loading of bracing for deep excavation has been reported, and the known beneficial effects are not fully understood and recognized by many practitioners. Model tests have been carried out to evaluate the efficiency of pre-loading system in reducing ground settlement as well as prediction of structural damage around excavation in sand. The test results revealed that the applied pre-loading of 50% and 70% showed about 20% of reduction in horizontal wall displacement and 30∼40% reduction in ground settlement. Also, bracing forces and earth pressure distribution behind the wall have been monitored during pre-loading at various excavation stages.

Development of a System Predicting Maximum Displacements of Earth Retaining Walls at Various Excavation Stages Using Artificial Neural Network (인공신경망을 이용한 굴착단계별 흙막이벽체의 최대변위 예측시스템 개발)

  • 김홍택;박성원;권영호;김진홍
    • Journal of the Korean Geotechnical Society
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    • v.16 no.1
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    • pp.83-97
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    • 2000
  • In the present study, artificial neural network based on the multi-layer perceptron is used and an optimum model is chosen through the process of efficiency evaluation in order to develop a system predicting maximum displacements of the earth retaining walls at various excavation stages. By analyzing the measured field data collected at various urban excavation sites in Korea, factors influencing on the behaviors of the excavation wall are examined. Among the measured data collected, reliable data are further selected on the basis of the performance ratio and are used as a data base. Data-based measurements are also utilized for both teaming and verifying the artificial neural network model. The learning is carried out by using the back-propagation algorithm based on the steepest descent method. Finally, to verify a validity of the formulated artificial neural network system, both the magnitude and the occurring position of the maximum horizontal displacement are predicted and compared with measured data at real excavation sites not included in the teaming process.

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Behavior of Building Lower Part Passage Tunnel due to Adjacent Ground Excavation (근접굴착에 따른 건물 하부 통과 터널의 거동)

  • Lee, Jong-Min;Lee, Sang-Duk
    • Tunnel and Underground Space
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    • v.20 no.5
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    • pp.369-377
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    • 2010
  • Applied to the braced wall in order to stabilize the adjacent tunnel. A pre-load of bracing was imposed to prevent the horizontal displacement of the braced wall during the ground excavation. For this purpose, real scale model tests were conducted, without and with pre-load on braced wall. Real scale model tests were conducted, without and with building load (0 m, 1D, 2D) on ground surface. As a result, it was found that the stability of the existing tunnel adjacent to the braced wall could be greatly enhanced when the horizontal displacement of the braced wall was reduced by applying a pre-load, which was larger than the designated axial force of bracing. In this paper, the behaviors of braced wall and adjacent tunnel was studied. Model tests in 1:10 scale were performed in real construction sequences. Adjacent tunnel was 12 m in diameter and the size of test pit was 2.0 m (width) ${\times}$ 6.0 m (height) ${\times}$ 4.0 m (length) in dimension.