• Title/Summary/Keyword: Curtain grouting

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The Impermeable Effect for Bedrock Constructed by Grouting (기반암에서 그라우팅에 의한 차수효과)

  • Yea, Geuguwen
    • Journal of the Korean GEO-environmental Society
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    • v.10 no.2
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    • pp.51-59
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    • 2009
  • This study is based on field data obtained from rock grouting such as RQD value, Unit cement grout volume, Lugeon value(Lu), and Maximum grout pressure in four different dam sites. The relationship were analyzed and compared as follow. The cut-off effect after rock grouting in dam-foundation which are mostly consist of metamorphic rock is better than that of Sedimentary rock. And the impermeable effect after consolidation grouting is more efficiency than the impermeable effect after curtain grouting. The unit cement grout volume are increased as RQD value is higher in rock mass. But there is no relationship between RQD value and Lugeon value. In the sedimentary rock, which is more permeable than metamorphic rock, Lugeon value (Lu) is a linear function (Lu=0.22Vc) of unit cement grout volume (Vc). Cut-off effect of curtain grouting is less influential at each near holes which are already grouted than that of consolidation grouting. And the behavior characteristics of Lugeon value vs. the unit cement grout volume as the order of installations are almost the same.

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A Study on the Impermeable Effect by Grouting in the Subsea Tunnel (해저터널에서 주입에 의한 차수효과 연구)

  • Kim, Seunghwan;Lim, Heuidae;Yoon, Seongmin
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.6
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    • pp.5-19
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    • 2017
  • In this study, the effect of rock mass curtain grouting was investigated by analyzing the correlation between the parameters of the RMR & grout injection volume, Lugeon value & RQD, Lugeon value & cement injection volume. In order to investigate the effect of rock mass curtain grouting, we analyzed the grout injection volume of 315 curtain grouting holes at 9 tunnel face of NATM Subsea tunnels in gneiss area. The total grout injection volume in the Subsea tunnels study was slightly changed in some tunnels face but decreased with increasing the rating of parameters in spacing of discontinuity (R3, Js) and groundwater condition (R5). The geological anomalies of seismic survey (3D, TSP) and the inflow of probe hole were found to be more correlated of relative than the parameters of RMR. The unit injection volume was found to decrease with higher ratings in the parameters of the RMR except the weathering degree of the discontinuity (Jc, R4). The correlation between RQD and Lugeon values is not significant, but it can be confirmed that the Lugeon value tends to decrease as the RQD value increases.

Reinforcement effect of surface stabilizer using surface curtain walls on aging reservoirs

  • Song, Sang-Huwon;Cho, Dae-Sung;Seo, Se-Gwan
    • Geomechanics and Engineering
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    • v.28 no.1
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    • pp.1-10
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    • 2022
  • In Korea, accidents related to the collapse of deteriorated aging reservoirs occur every year. The grouting method is generally applied to reinforce an aging reservoir. However, when using this method, different reinforcing effects appear depending on the ground conditions. Thus, new construction methods and materials capable of providing consistent reinforcing effects are required. In this study, the direct shear test (DST), model test, and simulation analysis were performed to evaluate the impact of surface stabilizers, generally used to reinforce roads, rivers, and slopes of roads, applied using surface curtain walls on aging reservoirs. The DST results indicate that when the surface stabilizer was mixed with in-situ soil, the increase in cohesion was the highest at a mixing ratio of 9%. No changes in the friction angle were evident; therefore, 9% was determined to be the optimal mixing ratio. In addition, the model test and simulation analysis showed that when 9% of the surface stabilizer was mixed and applied to the aging reservoir, the seepage quantity of water and the saturated area were reduced by approximately 42% and 73%, respectively. Moreover, the comprehensive analysis of results showed that the grouting method could be completely replaced by surface stabilizers applied through surface curtain walls because the technique could secure stability by decreasing the seepage in the aging reservoir.

Stability Analysis of Upper Structures by Soil Grouting (지반 그라우팅에 의한 상부구조물의 안전성 분석)

  • Hwang, Chulsung
    • Journal of the Korean Society of Safety
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    • v.28 no.4
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    • pp.58-65
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    • 2013
  • Transportation and further expansion of social infrastructure was needed along the development of urbanization and population concentration. To use the underground space due to the lack of availability of land, it is inevitable to intersect between present structure and tunnel during construction. Soil grouting is one of the ground improvement methods to reinforce weak soil around the underground structures by injection of grouting liquid. Some of central columns of an upper structure are damaged during injection of grouting liquid by injection pressure. To investigate and improve the stability of the tunnel, three dimensional analysis are performed with full construction stages which includes the construction of present underpass, damaging columns of the underpass, reinforcing the columns by H-pile and shear walls, and excavation and construct tunnel. The arrangement of grouting holes such as curtain and horizontal type affects largely to the stability of upper structure and horizontal arrangement diminish the shear forces which is the cause of damage of central columns. The liquid injection type of reinforcement for tunnel is not recommended while the presence of upper structure with columns. Wall type reinforcing is utilize for permant support of upper structures which is affected by grouting injection pressure. H-pile is utilize for temporary support, but not for permanent since the sharing of shear forces is not much to shear wall during tunnel construction.

Case Study on Seepage Analysis and Countermeasure Against the Seepage Flow of In-ground LNG Storage Tank (LNG 지하저장탱크의 침투해석 및 용수 대책공법에 대한 사례분석)

  • 신은철;오영인;이상혁
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.65-72
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    • 2001
  • Since Pyoungtaek thermal power plant began using natural gas in 1986, the annual using volume has rapidly increased and reached 12.7 million tons in 1999. When the natural gas is cooled to a temperature of approximately -162$^{\circ}$C at atmospheric pressure, it condenses to a liquid called liquefied natural gas(LNG). LNG has a special characters such as odorless, colorless, non-corrosive, and non-toxic. So, LNG storage tank, tanker ship, transfer pipelines are required the special storage and transportation systems and technology. The presently operating LNG terminals are Pyongtaek and Inchon terminals. A total of 19 above-ground LNG storage tanks(100 thousand ㎘ grade) are currently in operation with a sendout capacity of 4,360tons/hour. To meet the growing domestic demand of LNG supply, the Inchon receiving terminal is expanding(six in-ground tank) and constructing a third LNG terminal at Tongyong. In this paper, case study on seepage analysis and countermeasure against increasing the seepage volume of in-ground LNG storage tank excavation work is reported. The results of an additional seepage analysis are presented to verify the design seepage volume of assumption section and seepage volume after curtain-grouting in the slurry wall.

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A Case Study on the Ground Reinforcement Method and Effect of the Failed Tunnel (터널붕괴지반의 보강공법 및 효과에 대한 사례연구)

  • Cho, Hyun;Lim, Jae-Seung;Chung, Yoon-Young;Choi, Sang-Yeul
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.03a
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    • pp.293-300
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    • 1999
  • The maintenance for the stability of tunnel, especially on downtown area, careful check must be considered during construction stage and after. Moreover we have to achieve the stability of tunnel by ground improvement and reinforcement when ground condition is bad or tunnel failures under the various ground conditions. In this paper, it is presented the case of tunnel failure and the state of restoration by ground reinforcements at seoul subway $\bigcirc$-$\bigcirc$ construction site. For the purpose of ground reinforcement, first, curtain wall was established by chemical grouting. Secondly, cement milk grouting was carried by upper part of tunnel crown. Also Boreholes loading test and tunnel monitoring were carried by in failure site for the long term stability of tunnel.

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The Physical Properties Variation of Grout Materials and Improvement of Grouting Effects on Application of High Performance Injection Equipment (고성능 주입장비의 적용에 따른 주입재의 물성변화 및 주입효과 증진에 관한 연구)

  • 천병식;김진춘;김백영
    • Journal of the Korean Geotechnical Society
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    • v.19 no.4
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    • pp.179-190
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    • 2003
  • The grout based on solution type makes it difficult to get the improvement of ground strength and the effefct of water curtain because it has lower strength and durability than suspension type. Nowadays, the technology of particle acceleration, that enhance the material permeability, such as grout based on solution type, and inexpensive grout, is being required. For these reasons, in this study, using wet milling system, we evaluated physical properties of manufactured factors such as water-cement ratio of particles before being milled, optimum milling capacity by controlling milling time and rpm, viscosity of materials, permeation coefficient, and unconfined compressive strength. Also, using micro wet milling apparatus which could manufacture ordinary Portland cement and high speed shear mix which could forcefully separate conglomerate particles in situ, we performed electrical resistivity investigation and falling head permeability tests to analyze differences of grouting effects. From these results, we found that the permeability of the applied equipment was much superior, and in the case of using high speed shear mixer, particles of grout material were well separated.

Characteristics of Seepage Water and Groundwater in Incheon Coastal LPG Storage Cavern (인천 해안 저장공동 유출수 및 주변 지하수의 수질특성)

  • Jo, Yun-Ju;Lee, Jin-Yong;Choi, Mi-Jung;Cho, Byung-Wook
    • The Journal of Engineering Geology
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    • v.20 no.1
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    • pp.1-12
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    • 2010
  • The objective of this study was to examine the hydrogeochemical and microbiological characteristics for stable maintenance of coastal LPG storage cavern. Cavern seepage water and groundwater in the vicinity of the LPG storage cavern were sampled and analyzed (February, May, August and October 2007). Groundwater samples of propane cavern showed high pHs of 8.1~12.4 due to dissolution of cement grouting materials that had been applied during the well and cavern construction. The EC values showed distinctive seasonal variation. The negative ORP indicated reduced condition. The seepage and surrounding groundwater are classified as Na-Cl type, which represents seawater effects. All of aerobic bacteria, anaerobic bacteria, slime forming bacteria and sulfate reducing bacteria were less than 500 CFU/mL, which indicated that there was no abrupt increase of bacteria in the cavern. Therefore there exist no hydrochemical symptoms to indicate unstable conditions of the cavern operation. However, regular and continuous monitoring is essentially required.