• Title/Summary/Keyword: Ground Reinforcing

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Evaluation of Reinforcing Effects of Pressure-Injected Grouting Nail in Weathered Rock (풍화암 사면에서의 압력분사 그라우팅 네일 보강 효과 연구)

  • Hwang, Young-Cheol;Kim, Nak-Young
    • Journal of the Korean GEO-environmental Society
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    • v.3 no.1
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    • pp.47-55
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    • 2002
  • The slope reinforcing method utilized in this paper reinforces the ground overall by means of filling borehole as well as permeating grout material into ground by injecting it through the grouting pipe. In order to reflect these characteristics to design, not only the ground reinforcing effect by the structural material itself but also the ground strength improvement effect by the grouting injection must be quantitively evaluated. But precedent research of it has been insufficient. Therefore, the slope reinforcing method was applied to the weathered rockmass slope situated in the highway in order to analyze reinforcing effect and the instrumentation of slope was performed. Through analysis of this field test, the slope reinforcing method was proved to be effective and back analysis method based on instrumentation values of slope was proposed to apply to reinforcing design. In this paper, the effectiveness of reinforcing method was certified through proposed back analysis.

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Ground Behavior and Reinforcing Methods of NATM Tunnel through Deep Weathered Zone (NATM 터널의 대심도 풍화대층에서의 지반거동 및 보강방법)

  • Sung, Hwa-Don;An, Jung-Whan;Chun, Byung-Sik
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.1782-1788
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    • 2007
  • This study analyzed ground settlement and ground stress depending on tunnel excavation and the ground reinforcing grouting methods for double line road tunnel through deep weathered zone. Diameter of double line road tunnel was approximately 12m and umbrella arch method and side wall reinforcing grouting were applied. The ring-cut split excavation method and CD-cut excavation method for excavation method were applied. Analysis of failure rate and vertical stress ratio show that the tunnel for which the height of the cover(H) was higher than four times the diameter, it can be considered a deep tunnel. Comparisons of various excavation and ground reinforcement methods were showed that CD-cut method results in lower surface and crown settlement, and lower failure rate than where using Ring-cut split method. In addition the side wall reinforcing grouting resulted in reduction of tunnel displacement and settlement.

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An Experimental study on evaluation of reinforcing installation increasing the penetration depth about upset of concrete pole (콘크리트 전주의 근입깊이 증대를 위한 보강장치의 실험적 성능평가)

  • Shin, Dong-Geun;Yoon, Ki-Yong;Lee, Seung-Hyun;Lee, Gyu-Se;Kang, Young-Jong
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.71-74
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    • 2008
  • For reinforcing the overturn of concrete pole instituted in slope ground and weak ground, in this paper, develop the reinforcing installation. The installation increase penetration depth and effect of increasing the penetration depth is verified by experimental paper of Lim, jong suk(2004). In this research, through the experiment of bending test using the reinforcing installation, evaluate the performance. In the result of experiment, concrete pole behave elastically in design load and all sample are safe up to failure load.

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Reinforcing Effect of Pre-Tensioned Rock Bolts in the Jointed Rocks Condition (록볼트 긴장에 의한 수평절리암반의 보강효과)

  • An, Joung-Hwan;Lee, Sang-Duk
    • Tunnel and Underground Space
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    • v.19 no.5
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    • pp.388-396
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    • 2009
  • Rock bolt is one of the most important supports for tunnelling to prevent excessive ground relaxation at the primary tunnel excavation stage. It forms a ground arch band by confining the ground around a tunnel. Rock bolt has various effects, such as support or hanging effect, internal pressure effect, arching effect, ground improvement effect etc. Most studies on rock bolt focused on the concept of support, but only a few researches on the ground reinforcing effect by pre-tensioning a rock bolts. In this study, large scale model tests are performed to investigate the ground reinforcing effect of rock bolts for regularly jointed rocks. Simple beam model was built to find out the reinforcing effect of jointed rocks, which was reinforced by pre-tensioned rock bolts. Settlement of model beam was analyzed through measuring its sagging for various installation intervals.

Ground Behavior and Reinforcing Methods of NATM Tunnel through Deep Weathered Zone (대심도 풍화대층에서 NATM 터널의 지반거동 및 보강방법)

  • Chun, Byung-Sik;Song, Seung-Hoon;An, Jung-Whan
    • Journal of the Korean Geotechnical Society
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    • v.23 no.8
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    • pp.87-95
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    • 2007
  • This study analyzed ground settlement and ground stress depending on tunnel excavation and the ground reinforcing grouting methods for double line road tunnel through deep weathered zone. Diameter of double line road tunnel was approximately 12m and umbrella arch method and side wall reinforcing grouting were applied. The ring-cut split excavation method and CD-cut excavation method for excavation method were applied. Analyses of failure rate and vertical stress ratio show that the tunnel for which the height of the cover (H) was higher than four times the diameter, can be considered a deep tunnel. Comparisons of various excavation and ground reinforcement methods showed that CD-cut method results in lower surface and crown settlement, and lower failure rate than that obtained by Ring-cut split method. In addition, the side wall reinforcing grouting resulted in reduction of tunnel displacement and settlement.

Experimental Study on Lateral Flow Behavior of Soft Ground due to Embankment (성토로 인한 연약지반의 측방유동 거동에 관한 실내모형실험)

  • You, Seung-Kyong;Kim, Jae-Hong
    • Journal of the Korean Geosynthetics Society
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    • v.10 no.1
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    • pp.43-51
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    • 2011
  • Pile-supported embankment is one of the reinforcing methods to minimize damage due to the severe subsidence and lateral flow when soft clay ground is supported with embankment. pile-supported embankment mainly penetrates soft ground into the bearing stratum in order to support surcharge load which minimizes the subsidence and lateral flow due to the surcharge load. The aim of this research is to review quantitatively reinforcing effect of pile-supported embankment which is installed in soft clay ground. From the model test, it reproduced the ground movement with regard to the non-reinforced and reinforcing embankment-pile and also analyzed stabilizing effects of lateral flow due to the pile-supported embankment. With regard to the case of installing pile-supported embankment, its were analyzed stabilizing effects of lateral flow in cases of quick-load and slow-load to make different surcharge load.

The Case Studies on Application of Mat Foundation System to Building Structure Founded on Weathered Ground (풍화대지반에 지지된 건축구조물의 전면기초 적용에 관한 사례 연구)

  • Choi, Yongkyu;Kim, Sungho;Lee, Minhee
    • Journal of the Korean GEO-environmental Society
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    • v.10 no.6
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    • pp.5-18
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    • 2009
  • In construction of buildings in Korea, the buildings are frequently founded on the weathered ground (weathered soil/rock, fractured rock). In this case, to make a full use of a bearing capacity of a weathered ground for economic design, the shallow mat foundation system could be used. In this study, we have researched three cases of mat foundations on the weathered ground in Korea, and analyzed and considered the design procedures and the reinforcing methods. That is, we have considered the detail design, analysis proceedings, the ground settlement evaluation proceedings, the rock face mapping evaluations after excavation and reinforcing methods of the mat foundation on the weathered ground. And large scale plate load tests on the weathered ground supporting the mat foundation were performed and also load bearing capacity and settlement of actual mat foundation, considering the scale effect, were evaluated.

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A Safety Analysis of the BTR Method by Construction Sequence (BTR공법의 시공단계별 안전성 해석)

  • Chung, Kuang-Mo;Lee, Won-Hee;Lee, Sang-Hyun;Bang, Myung-Seok
    • Journal of the Korea Safety Management & Science
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    • v.14 no.1
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    • pp.101-108
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    • 2012
  • In this study was conducted numerical analysis to evaluate the stability of BTR(Built-in Timber Roof Tunneling Method), which is one of construction methods of underground structures in the non-opening state. The discretion method was applied to individually model reinforcing members of BTR, and the homogeneity analysis technic by area ratio was used to verify the feasibility comparing this result with that from conventional analysis method. The parameter study was performed to evaluate the effect varying ground depth, distance length of reinforcing supports and to verify the field applicability of new analysis method. The results showed the very precise value with allowable error, so this method can be applied in the field, The more length of supporting members caused the more vertical displacement and the top displacement increment of support members is larger than that of ground surace. The effect of ground depth was more impressive than that of distance length of reinforcing supports.

Acceleration amplification characteristics of embankment reinforced with rubble mound

  • Jung-Won Yun;Jin-Tae Han;Jae-Kwang Ahn
    • Geomechanics and Engineering
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    • v.36 no.2
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    • pp.157-166
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    • 2024
  • Generally, the rubble mound installed on the slope embankment of the open-type wharf is designed based on the impact of wave force, with no consideration for the impact of seismic force. Therefore, in this study, dynamic centrifuge model test results were analyzed to examine the acceleration amplification of embankment reinforced with rubble mound under seismic conditions. The experimental results show that when rubble mounds were installed on the ground surface of the embankment, acceleration response of embankment decreased by approximately 22%, and imbalance in ground settlement decreased significantly from eight to two times. Furthermore, based on the experimental results, one-dimensional site response (1DSR) analyses were conducted. The analysis results indicated that reinforcing the embankment with rubble mound can decrease the peak ground acceleration (PGA) and short period response (below 0.6 seconds) of the ground surface by approximately 28%. However, no significant impact on the long period response (above 0.6 seconds) was observed. Additionally, in ground with lower relative density, a significant decrease in response and wide range of reduced periods were observed. Considering that the reduced short period range corresponds to the critical periods in the design response spectrum, reinforcing the loose ground with rubble mound can effectively decrease the acceleration response of the ground surface.

Design Method of Spread Footing of Semicircular Shape Reinforced by Geosynthetics (토목섬유로 보강된 반원형상의 확대기초의 설계법)

  • Ju, Jae-Woo;Lee, Seung-Eun;Park, Jong-Beom;Kim, Ki-Seong
    • Journal of the Korean Geosynthetics Society
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    • v.3 no.4
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    • pp.41-48
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    • 2004
  • Recently a method for increasing the bearing capacity by laying the reinforcing materials with three or four layers as a method reinforcing the ground was studied recently. The purpose of this study is to examine the method for increasing shear-strength factor of the ground by reinforcing the ground under the foundation. According a method of wrapping ground with bakk-shape or semicircle-shape by geotextile was developed in this study and it looks likes anaspect that spreading footing exits under spread footing. A simulation loading-test using Aluminum sticks was carried out in order to examine the mechanism about bearing capacity of spread footing reinforced by geotextile. Increase of ultimate bearing capacity was verified in this simulation loading-test when charging loads to spread footing, which is propose from this study, reinforced by geotextile. And moving directions of points of the ground were also checked by grid-type indication method, and the areas where plastic failure appeared were checked by B-shutter photographing.

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