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Research Article

A Study on the Increase of Bearing Capacity of Soft Ground in Shallow Foundation Using High Density Rapid Expansion Material

고밀도 급속 팽창재를 이용한 얕은기초 연약지반의 지내력 증대에 관한 연구

Euichul Ro1
,
Daehyeon Kim2*
노 의철1
,
김 대현2*
1Graduated Student, Department of Civil Engineering, Chosun University
2Professor, Department of Civil Engineering, Chosun University
1조선대학교 토목공학과 박사과정
2조선대학교 토목공학과 교수
*Corresponding Author
30 June 2020. pp. 185-198
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Abstract

High-density rapid expansion material is a method that increases the solid volume of injection materials due to hydration and foam reactions at the same time as spraying. It is an effective method for securing ground stability, restoring subsidence, and loading during construction of structures. In this regard, through the mechanical experiments of injection materials, the stability of the foundation ground of the structure and the effect of increasing the endurance using site construction were analyzed. The results of the experiment showed that the unit weight of soil decreased by 10.5% after injection of the filling material, and the allowable support for the structure was deemed safe, and the subsidence by each section after ground improvement was determined to be safe at 2.28, 1.55 and 0.46 cm, respectively, with an acceptable subsidence of less than 5 cm. After the field test, five inclinometers were installed on the top floor of the target building to measure the displacement of the X and Y axes. As a result of the measurement, no displacement related to the phenomenon of inequality or subsidence cracks of the structure was measured for about 16 months (509 days) after construction. This can be judged to be a sufficient increase in the stability of the ground after the injection of rapid expansion.

Keywords
expansion material
foam reaction
allowable bearing capacity
consolidation
soft ground

고밀도 급속 팽창재는 주입과 동시에 화학반응으로 인한 순간 발포반응이 생겨 주입재료의 고결부피를 증가시키는 공법으로써 구조물 축조 시 지반의 안정성 확보, 침하 구조물복원 및 차수에 효과적인 공법이다. 이와 관련하여 본 연구에서는 주입재료의 역학적 실험을 통하여 구조물 기초지반의 안정성 평가와 현장시공을 이용한 지내력 증대 효과를 분석하였다. 실험 결과, 사질토 지반의 경우 주입재의 주입 후 약 10.5% 정도 흙의 단위 중량이 감소 된 것으로 확인되었으며, 구조물에 대한 허용지지력 모두 안전하다고 판단되었고 지반개량 후 각 단면별 침하량은 허용 침하량 5 cm 이내인 2.28, 1.55, 0.46 cm로써 안전하다고 판단되었다. 현장 실험 후 대상 건축물의 최상층에 5개의 경사계를 설치하여 X, Y축에 대한 변위를 측정하였다. 계측결과, 시공 후 약 16개월(509일)동안 구조물의 부등침하 또는 침하균열 현상과 관련된 변위는 측정되지 않았다. 이는 급속 팽창재의 주입 후 지반의 안정성이 충분히 증대된 것이라고 판단할 수 있다.

키워드
팽창재
발포반응
허용 지지력
허용 침하량
압밀
연약지반
References
1
Chae, Y.S., Lee, G.I., 1996, The effect of the ground reinforcement by the high polymer urethane grouting method, Journal of Academic Presentation and Seminar of the Korean Society of Geotechnical Engineering, 1996(5), 21-29.
2
Cheon, B.S., Ryu, D.S., Kim, J.D., Ryu, J.Y., 1997, The effectiveness of polyurethane as auxiliary method of soil nailing system, Journal of Academic Presentation of the Korean Civil Society, 3, 489-492.
3
Gwon, H.J., Kim, J.S., Park, J.B., Jung, S.K., 2007, Foundation engineering, Goomibook, 493p.
4
Han, J.K., Ryu, Y.S., Kim, D.W., Park, J.J., Hong, G.W., 2017, A study on expansion and strength characteristics of material for emergency restoration in ground cavity, Journal of the Korean Geosynthetics Society, 16(2), 131-138 (in Korean with English abstract).
5
Han, W.J., Lee, J.S., Byun, Y.H., 2018, Engineering properties of lightweight foaming grouting materials for underground cavities, Journal of the Korean Geo-Environmental Society, 19(2), 5-12 (in Korean with English abstract).
6
Jeong, K.H., Kim, J.Y., Lee, S.J., 2010, A Case Study on Slope and Earth Retaining Wall Reinforced by Pressure-Ground Soil Nailing, Korean Geotechnical Society, 97-108.
7
Jung, D.H., Chung, D.S., You, S.K., Kim, J.H., Han, J.G., 2017, Mechanical property enhancement of water soluble polymer pouch for ground reinforcement, Journal of the Korean Geosynthetics Society, 16(4), 221-230 (in Korean with English abstract).
8
Kim, J.I., Cheon, B.S., Ryu, D.S., Nam, S.S., Oh, S.J., 1995, A study on the properties and construction examples of urethane-based chemicals for rock injection, Journal of Academic Presentation of the Korean Civil Society, 2, 405-408.
9
Kim, Y.H., Chung, D.S., Jeong, S.H., You, S.K., Han, J.G., 2016, Experimental Study on The Shape of Underground Cavity according to Fine Grained Soil Contents, Korean Society of Geotechnical Engineering Autumn Conference.
10
Kim, Y.H., Kim, H.Y., Kim, Y.S., You, S.K., Han, J.G., 2017, Experimental study for confirmation of relaxation zone in the underground cavity expansion, Journal of the Korean Geosynthetics Society, 16(4), 231-240 (in Korean with English abstract).
11
Lee, S.S., 2009, A study on ground reinforcement using GPCON method, Master Thesis, University of Seoul, 1-80.
12
Lee, S.Y., Yoon, H.H., Son, M., Kong, J.Y., Jung, H.S., 2018, Controlled low strength material for emergency restoration using bottom ash and gypsum, Journal of the Korean Geosynthetics Society, 17(2), 19-31 (in Korean with English abstract).
13
Lee, Y.H., 2005, A study on the characteristics of underground stress on the ground surface of the two-story ground above the soft clay layer, Doctor Thesis, University of Mokpo, 1-221.
14
Shin, E.C., Cha, Y.I., 2008, Engineering characteristic of high density expansion materials for structure restoration technology, Journal of the Korean Geosynthetics Society, 7(2), 1-5 (in Korean with English abstract).
15
Yu, N.J., Chung, D.S., You, S.K., Park, J.Y., Kim, Y.H., Han, J.G., 2016, An Experimental Study through Various Mixing Ratio of Filling Material for Rapid Reinforcing on Ground Sink: Considering Strength of Neighboring Ground, Korean Geosynthetics Society Academic Presentation Conference, 23-24.
Information
  • Publisher :Korean Society of Engineering Geology
  • Publisher(Ko) :대한지질공학회
  • Journal Title :The Journal of Engineering Geology
  • Journal Title(Ko) :지질공학
  • Volume : 30
  • No :2
  • Pages :185-198
  • Received Date : 2020-06-11
  • Accepted Date : 2020-06-17
  • DOI :https://doi.org/10.9720/kseg.2020.2.185
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