• Title/Summary/Keyword: Jet-grouting method

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Square Jet Grouting to Reduce Permeability (사각(四角)제트 그라우팅 공법에 의한 지반차수 특성)

  • Gwak, Soo-Jeong;Baek, Hong-Ryul
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.188-197
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    • 2005
  • Square patterned jet grouting technique is the soil improvement method that shakes the special end monitor left and right like as tail fin and mixing the soil and cement paste after cutting the soil in square shape by injecting the cement paste from installed two nozzles. The structure shape by jet grouting technique can be constructed in various shapes and sizes like as square, circle, and sector form designed by an engineer. Also, it can be constructed without waste material and reduced a construction time of work economically. In this study, the applicability of Square Jet Grouting to reduce permeability is estimated by FEM analysis and in-situ test in many cases which are various coefficient of permeability and breadth of grouting structure.

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A CASE STUDY OF FEM ANALYSIS ON GROUND REINFORCEMENT USING HORIZONTAL JET GROUT ROOFING IN SOFT GROUND TUNNELING (연약 지층 터널의 보강공법에 관한 FEM 해석 사례연구)

  • 김주봉;문상조
    • Proceedings of the Korean Geotechical Society Conference
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    • 1993.10a
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    • pp.51-56
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    • 1993
  • This paper presents the FEM anlysis results performed to assess the applicability of Horizontal Jet Grout Roofing, and of ground improvement methods for tunneling in soft ground. Horizontal Jet Grount Roofing Method is applicable to ensure the stability of tunnel face in non-cemeted alluvial strata under high ground water pressure. For applying this method, to ensure the reliability, the Horizontel Jet Grout Roofing should be double lined with pre-grouting to reduce the water inflow during the jet grouting.

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Case Studies on Ground Improvement by High Pressure Jet Grouting(I) Effect in the Improvement of Bearing Capacity for Foundation Ground (고압분사주입공법에 의한 지반개량사례연구(I) -구조물 기초지반의 지지력증대효과)

  • Yun, Jung-Man;Hong, Won-Pyo;Yu, Seung-Gyeong
    • Geotechnical Engineering
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    • v.12 no.4
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    • pp.33-46
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    • 1996
  • When structures are constructed in ground with poor bearing capacity, deformation of ground may induce foundation settlements and cracks of structures. Recently, high pressure jet grouting is widely used to improve the engineering properties of such foundation. Sometimes, the grouting columns are built in the ground by jet grouting method. They are used as in -situ piles to increase the bearing capacity of existing foundation. In this paper, as for the grouting columns built in ground by high pressure jet grouting with double tube rod, the effects on reinforcement and bearing capacity of ground are investigated. A series of laboratory tests has been performed on the specimens sampled from the grouting columns and a pile load test has been performed on a grouting column. The test results show that high pressure jet grouting has a sufficient effect on reinforcement of ground and restraint of settlement of structure.

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The Behaviour Characteristics of Reinforced Limestone Cavities by High Pressure Jet-Grouting (고압분사주입공법으로 보강된 석회암공동의 거동특성)

  • Hong, Won-Pyo;Hong, Kun-Pyo;Yea, Geu-Guwen
    • The Journal of Engineering Geology
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    • v.18 no.1
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    • pp.7-16
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    • 2008
  • Limestone area have mostly certain geological defects such as the internal cavities due to melting and fractured zone by external pressures. Especially, in case of constructing grand bridge, the treatment of the limestone cavities area having the geological defects is inevitable. In order to reduce foundation settlement and to reinforce the ground in the limestone cavities area, high pressure jet grouting has been carried out as a countermeasure method. Despite the fact that high pressure jet grouting method has already adopted at a lot of limestone cavities area, but the amount of research and technical data on the high pressure jet grouting have not been accumulated properly so for. Therefore this paper intends to investigate the strength characteristics and deformation characteristics for reinforced limestone cavities area by high pressure jet grouting method. In addition, load carrying capacity obtained by static pile load test with load transfer measuring system is analyzed.

Experimental Study on Enhanced Jet Grouting by Cavitation Theory (공동현상 이론을 고압분사주입공법에 적용하기 위한 실험적 연구)

  • Lee Sang-Ik;Kim Chang-Jong;Oh Se-Hun;Kim Young-Uk
    • Journal of the Korean Geotechnical Society
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    • v.21 no.1
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    • pp.43-50
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    • 2005
  • Jet grouting method is widely being used in many geotechnical problems, especially for the purpose of reinforcement of clayey ground and cut-off wall of sandy ground. However, its design depends on highly empirical method, in which many researches have been undertaken. This study investigated the effect of cavitation on jet grouting. Small-scaled model tests were carried out using specially designed and fabricated device to analyze the effect of cavitation on jet grouting with various test conditions including ground condition, injection pressure, and injection time. The test results show that cavitation has a significant effect on jet grouting, and it has a potential for engineering application.

Mechanical Properties of the Ground Improved by High Pressure Jet-Grouting and Analysis of Deformation of Propped Retaining Walls (고압분사주입공법으로 보강된 개량체의 특성 및 흙막이벽의 변형해석)

  • 심태섭;주승완
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.42 no.6
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    • pp.98-105
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    • 2000
  • Recently, the construction method of high pressure jet-grouting is in wide-use, for the purpose of structure foundation ground, reinforcing of ground behind propped retaining walls and cut-off in order to perform safe construction of underground excavation work. This study was performed a serious of tests of field permeability and unconfined compressive strength upon ground improved established on the ground behind propped retaining walls and examined proper jet mechanism by changing the construction parameter value of high pressure jet-grouting. In addition, we got the conclusion like the followings as a result of inspecting the condition of earth pressure distribution and deformation, using elasto-plastic method and FEM. 1. In that characteristics of strength of ground improved, with the same condition of construction parameter, unconfined compressive strength of sand gravel is shown bigger than that of silty sand by about 1.6 times and cut-off effect is shown to have effect of reducing the permeability of original ground by about 10$^{-2}$ ~10$^{-3}$ cm/s. 2. As a result of analysis of figures of horizontal displacing quantity of propped retaining walls materials regarding before and after High pressure jet- grouting through FEM, the reducing quantity of 0.1~0.3mm in maximum horizontal displacement is shown.

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Case Studies on Ground Improvement by High Pressure Jet Grouting(II) Effect on the Ground Reinforcement and Cut off of Ground Water Behind Temporary Retaining Walls (고압분사주입공법에 의한 지반개량사례연구(II) -흙막이벽 배면지반보강 및 차수효과)

  • Yun, Jung-Man;Hong, Won-Pyo;Jeong, Hyeong-Yong
    • Geotechnical Engineering
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    • v.12 no.5
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    • pp.5-16
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    • 1996
  • When braced excavation with temporary retaining wall installation, is performed in loose sand with high ground water level boiling may be induced and considerable damage on the excavation works and structures in the vicinity can take place. Recently, for the purpose of reinforcement of ground and cut-off of ground water behind the temporary retaining wall, high pressure jet grouting is widely used. The purpose of this paper is to investigate the effects of jet grouting on ground reinforcement and cut -off of the ground water behind temporary retaining walls for braced excavation. A series of both laboratory and field tests has been performed. The test results show that high pressure jet grouting has sufficient effects on reinforcement of stiffness of ground and retaining wall. The permeability of the improved ground was 10-f_ 10-3cm l s smaller than those of the original ground. Therefore, the effect on cut off of ground water behind temporary retaining walls could be improved by high pressure jet grouting method.

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A Study on the Application of MJM for Ground (MJM 주입공법의 현장적용성에 관한 연구)

  • Chun, Byung-Sik;Choi, Choon-Sik;Roh, Jong-Ryun;Lee, Seung-Joon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.437-442
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    • 2005
  • The high pressure jet grouting method is mainly used in the grouting. But, this method has problems that the scale and strength of improved body is not constant with ground condition. Considering these problems, triple rod MJM that results in the high-strength effect by the technology of the injected ${\phi}7mm$ cement mortar was developed. In this MJM, the unconfined strength is estimated with the various combination ratio and engineering characteristic, strength improvement effect of improved body, was checked through the field test. It is known that the application of MJM was verified with ground and construction condition.

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The Evaluation of reinforcing method for the pier foundations on the karstic areas containing the solution cavities in Korea (국내의 석회암 공동지역 기초지반보강법에 대한 평가)

  • Im, Soo-Been;Noh, Seung-Han;Jegal, Ho
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.499-509
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    • 2005
  • We have many foundations which were constructed on the karstic areas where solution cavities and fractured zone may form under, or close to foundations. The fact that the ground under the pier foundations was reinforced with the three axial high pressure jet grouting is confirmed through out about two hundred design reports. It is necessary that evaluation of a simple application of high pressure jet grouting method on the karstic areas containing solution cavities. In this study, the improved situation and reinforcing methods of the ground under the pier foundations are proposed based on the evaluation of design reports for the express highway and No.38 national roads.

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Evaluation of Axial Bearing Capacity of Waveform Micropile by Centrifuge Test (원심모형실험을 통한 파형 마이크로파일의 연직 지지력 평가)

  • Jang, Young-Eun;Han, Jin-Tae;Kim, Jae-Hyun;Park, Heon-Joon;Kim, Sang-Hwan
    • Journal of the Korean Geotechnical Society
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    • v.31 no.8
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    • pp.39-49
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    • 2015
  • In this study, a series of centrifuge tests were performed in order to observe the bearing capacity of waveform micropile, a new concept of micropile that uses a modified jet grouting process. A total of six models were considered, conventional micropile, jet grouted pile, and four different shapes of waveform micropiles. The test results indicated that the waveform micropile effectively contributes to the increase of the bearing capacity compared to the micropile without the shear keys. Among the waveform micropiles, the model that has a relatively small space between the shear keys showed the most significant improvement of load capacity. Additionally, the ultimate load capacities of all piles were compared using well-known estimation method. As a result, P-S curve method and total settlement method with 25.4 mm were considered suitable to account ultimate load for the waveform micropile.