• Title/Summary/Keyword: grouting reinforcement

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Verification of Reinforcement with Grouting Materials in Reservoir Dike using Electrical Resistivity Tomography (전기비저항 토모그래피를 이용한 저수지 제체 그라우팅 효과 검증)

  • Song, Sung-Ho;Yong, Hwan-Ho;Lee, Gyu-Sang;Woo, Myung-Ha
    • 한국지구물리탐사학회:학술대회논문집
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    • 2006.06a
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    • pp.73-78
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    • 2006
  • To verify reinforcing effect of grouting materials on the water leakage region in dike, we performed various hydraulic test and we also applied electric resistivity survey including electrical resistivity tomography(ERT) to see resistivity variation before and after grouting. As the results of dipole-dipole array survey along dike, resistivity distribution after grouting was without noticeable spatial variation. Long term resistivity monitoring results at dike with Schlumberger array electric resistivity survey showed that the decreasing region of apparent resistivity and one dimensional inversion results were the occupied region by grout after grouting. From the ERT using check holes to inspect the effect of grouting, we could find that the ERT is quite effective to evaluate spatially grout region in dike.

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Pullout Characteristics of Pressure Reinjection-Grouted Reinforcements in Clay (점성토 지반에 설치된 압력재주입 그라우팅 보강재의 인발특성)

  • Seo, Jungwon;Kim, Nara;Lee, Bongjik
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.9
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    • pp.83-89
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    • 2012
  • Anchor, soil nail and micropile have been widely used for slope reinforcement and foundation. These all methods need grouting work after placing reinforcing member. The pressure injection-grouting techniques helps to increase the bearing capacity of reinforcing member by enhancing larger effective pile diameter and increasing the radial stresses acting on the grout body and causing irregular surface. However, the pressure reinjection-grouting techniques is not commonly used because grouting equipment and practical application example are short and the verification of reinforcing effect is difficult. In this study, the laboratory test was performed to evaluate the reinforcing effect with variation of grouting methods in clay. As a result of the test, the pressure reinjection-grouting techniques showed that the pullout capacity of reinforcing member increased up to 1.22~2.61 times comparing to the gravity fill techniques.

A Study on Bearing Capacity Reinforcement for PHC Pile Foundation Using Post-grouting (그라우팅 기법을 활용한 PHC 파일 기초의 지지력 증강 효과 연구)

  • Yoo, Min-Taek;Lee, Su-Hyung;Kim, Seok-Jung;Choi, Yeong-Tae;Park, Jeongjun
    • Journal of the Korean Geotechnical Society
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    • v.33 no.6
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    • pp.17-25
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    • 2017
  • In this research, post grouting methods were applied on PHC piles, and static load tests were conducted to confirm the effect of post grouting on bearing capacity enhancement of PHC piles. Grouting pressures of 1.9 MPa and 3.5 MPa were applied, and bearing capacities of grouted piles were compared with that of non-grouted pile. From the static load test results, the bearing capacities of grouted piles were about 3 times higher than that of non-grouted pile. In addition, the design efficiency (allowable bearing capacity/nominal bearing capacity) increased from 32% to 97% after post grouting, and the axial stiffness of piles also increased by about 1.3 times per grouting pressure.

A Study on the Ground Reinforcement and Impermeable Effect by McG (McG(맥) 주입공법에 의한 지반보강 및 차수효과에 관한 연구)

  • Chun, Byung-Sik;Jung, Jong-Ju;Chung, Chang-Hee;Do, Kyung-Yang;Do, Jong-Nam
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.352-361
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    • 2006
  • The grouting method is widely used in construction to reduce permeability and reinforce the ground. If the cement and grout material are not mixed well in the injection tip equipment, an opposite flow and Interception state of the chemical grouting can occur. McG method installs a special grouting device to allow better mixing of the grouting material and prevent backward flow. The block of nozzle also diversify powder rate of cement. YSS that lowers $Na_2O$ and thereby increases durability is developed by gel-forming reaction material. In this study, the seepage state and unconfined compressive strength of the injection material using the special injection tip equipment is tested. The results of laboratory and field tests clearly demonstrate that the strength increases and permeability decreases using the McG method.

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A Study of Stability Evaluation for Tunnel at the Fault Zone Crossing (단층대를 통과하는 터널의 안정성확보에 관한 연구)

  • 박인준;최정환;김수일
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.105-112
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    • 2001
  • The purpose of this study is to assess the stability of tunnel for a high speed railway crossing the fault zone. The area where the tunnel crossed the fault zone can be unstable during construction and operation. Geotechnical investigations have been conducted to determine an optimum excavation method by obtaining the material properties around the fault zone and to check the stability of the tunnel. For the numerical analysis, the FLAC, numerical analysis code based on finite difference method, was utilized to analyze the behavior of the fault at three points having typical ground conditions. Based on the results of numerical analysis, the combinations of compaction grouting and LW grouting were determined as suitable methods for pre-excavation Improvement of the ground surrounding the tunnel opening. In conclusion, the stability of the tunnel construction for the high speed railway within the fault zone may be obtained by adopting the optimum excavation method and the reinforcement method. The numerical analysis based on FLAC program contains errors caused by assumptions used in numerical analysis, therefore constant monitoring with respect to the change of ground condition and groundwater is highly recommended to minimize the numerical error and the possibility of damage to tunnel.

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Case Study of a Shallow Tunnelling Through Complex Strata of Sand-Gravel and Rock Mass (모래자갈과 암반의 복합지층에 시공한 저심도 터널의 사례연구)

  • Kim, Cheehwan
    • Tunnel and Underground Space
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    • v.25 no.3
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    • pp.244-254
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    • 2015
  • The tunnel is excavated through the alluvial layer composed of sand and gravel with groundwater deposited on rock. A portion of upper part of the tunnel is located in the alluvial layer and there are several buildings just above the curved section of the tunnel. It is necessary to prevent from sand-flowing into the tunnel due to low strength of the alluvial, high groundwater level and shallow depth of the tunnel from the ground surface. For this, the alluvial around the tunnel is pre-reinforced by umbrella arch method with multi-stage grouting through large diameter steel pipes or jet grouting before excavating the tunnel. The effect of the pre-reinforcement of the tunnel and the safety of the buildings are monitored by measurement of ground deformation occurred during tunnelling.

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.

A Study on the Grouting Effect of Ultrafine Cement in Rock Ground (초미립자 시멘트의 암반지반 그라우팅 주입효과에 관한 연구)

  • An, Jun-Hee;Park, Choon-Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.12
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    • pp.279-286
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    • 2018
  • The grouting method is to reinforce the ground by injecting the chemical solution for the strengthening of the ground. Cement grouting material has usually used portland cement for centuries ago, but the cement particle size is large and the injection effect is limited. This study analyzes the effect of ultrafine cement grouting in rock ground using 3S-1 grouting in rock ground and ordinary Portland cement (OPC). The results of tests were compared and analyzed from the Lugeon test, bore loading test (P.M.T.), and injection (P-Q) test. The use of ultrafine cement (3S-1) had a higher effect (K, 10-6cm/sec) than OPC. The reinforcement effect of 3S-1 was also confirmed. Ultrafine cement (3S-1) was 4~9 times more injectable than OPC. Therefore, it is more advantageous to use ultrafine cement (3S-1) than OPC.

A Study on the Reinforcement of Rock Faults by Grouting (암석 절리면의 그라우팅에 의한 보강에 관한 연구)

  • Chun, Byung-Sik;Choi, Joong-Keun
    • Journal of the Korean GEO-environmental Society
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    • v.4 no.4
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    • pp.45-51
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    • 2003
  • Grouting materials in rock is grouted as vein type along the fault surface by the other way for soil and allow a change of characteristics in rock faults as a result of that. Therefore the deformation characteristics of rock faults after grouting differ as a direction and characteristic of grouted fault and stress condition of field rock. Thereby it must be analyzed the effect for deformation of rock according to characteristics of rock faults and characteristics of grouting materials to accurately evaluate the reinforced effect by grouting. But grouting method used in field until present depends on experience of workers, and inspection for those effects are evaluated by measurement of elastic wave velocity, permeability tests and etc. in field. In this study, it was investigated that the effects for shear characteristics of maximum shear strength, residual shear strength and etc. by comparison and analysis of test results which were worked by direct shear tests of rock faults with changing a type of grouting materials and the grouting depth(t) for average width(a) of fault surface roughness when OPC(Ordinary Portland Cement) and Micro cement was grouted in fault surface of field rock to evaluate characteristicsof the shear deformation for rock fault surface of dam by grouting.

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Applications of Improved Low-Flow Mortar Type Grouting Method for Road Safety and Constructability in Dangerous Steep Slopes (급경사지 붕괴 위험지역의 도로 안전 및 시공성을 고려한 개선된 저유동 몰탈형 그라우팅공법 적용성 분석)

  • Choi, Gisung;Kim, Seokhyun;Kim, Nakseok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.40 no.4
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    • pp.409-415
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    • 2020
  • Low-flow mortar injection method grouting technology was selected and the traffic area was preserved as much as possible in order to secure safety for road traffic when the outflow and subsidence of landfill occurred due to ground-water, and etc. In particular, the current existing method was newly improved since there are risks of damage such as hydraulic fracturing at the lower part of the road, spilling of soil particles on steep slopes, and bumps on the road due to excessive injection pressure during construction. This study was carried out at the site of reinforcement work on the road as a maintenance work for the danger zone for collapse of the steep slope of the 00 hill, which was ordered from the 00 city 00 province. The improved low-flow mortar type grouting method adopted a new automated grouting management system and especially, it composites the method for grouting conditions decision by high-pressure pre-grouting test and injection technology by AGS-controlled and studied about grouting effect analysis by using new technology. By applying the improved low-flow mortar type grouting method, it was possible to lay the groundwork for road maintenance work such as the prevention of subsidence of old roads, uneven subsidence of buildings and civil engineering structures, and of soil leakage of ground-water spills. Furthermore, the possibility of application on future grouting work not only for just construction that prevents subsidence of old roads but also for various buildings and civil engineering structures such as railroads, subways, bridges, underground structures, and boulder stone and limestone areas was confirmed.