• Title/Summary/Keyword: grouting reinforcement

Search Result 213, Processing Time 0.02 seconds

A Case Study on the Slope Reinforcement by Improved Steel Pipe Nailing (개량 강관네일링 공법을 이용한 사면 보강사례 연구)

  • Choi, Dong-Nam;Lim, Heui-Dae;Song, Young-Su;Lee, Kyu-Hwan
    • Journal of the Korean Society of Safety
    • /
    • v.22 no.1 s.79
    • /
    • pp.54-60
    • /
    • 2007
  • This paper describes typical design and construction practice for in-situ ground reinforcement technique using improved steel pipe pressure grouting. A case history is presented to illustrate the benefit gained by application of the technique. This technique was applied to cut slopes developed in the construction of auxiliary spillway of 00 dam. Applicable conditions, method of survey, slope stability analysis and construction are given in this parer. As for the construction method, a procedure is given and the main points are the control of construction work. As a result of the pull-out test, it is shown that seel pipe nailing is particularly useful for stabilizing rock slope.

Evaluation of Face Stability of Tunnel with Steel Pipe-Reinforced Multi-step Grouting (강관다단 그라우팅으로 보강된 터널의 막장 안정성 평가)

  • 이인모;이재성;남석우
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2003.03a
    • /
    • pp.273-280
    • /
    • 2003
  • Tunneling in difficult geological conditions is often inevitable especially in urban areas. Ground improvement and reinforcement techniques are often required to guarantee safe tunnel excavations and/or to prevent damage to adjacent structures. The steel pipe-reinforced multi-step grouting method has been recently applied to tunnel sites in Korea as an auxiliary technique. In this study, the face stability with steel pipe-reinforced multi-step grouting was evaluated by simultaneously considering two factors: one is the effective stress acting on the tunnel face calculated by limit theorem and limit equilibrium method; the other is the seepage force obtained by means of numerical analysis. The study revealed that the influence of the steel pipe-reinforced multi-step grouting on the support pressure in dry condition is not significant while there is relatively a large amount of reduction in seepage forces by adopting the technique in saturated condition. The effect of the anisotropy of permeability on the seepage force acting on the tunnel face was also estimated by conducting the coupled analysis. It was found that a higher horizontal permeability compared with the vertical one causes reduction in the seepage force acting on the tunnel face.

  • PDF

Seismic performances of RC columns reinforced with screw ribbed reinforcements connected by mechanical splice

  • Lee, Se-Jung;Lee, Deuck Hang;Kim, Kang Su;Oh, Jae-Yuel;Park, Min-Kook;Yang, Il-Seung
    • Computers and Concrete
    • /
    • v.12 no.2
    • /
    • pp.131-149
    • /
    • 2013
  • Various types of reinforcement splicing methods have been developed and implemented in reinforced concrete construction projects for achieving the continuity of reinforcements. Due to the complicated reinforcement arrangements and the difficulties in securing bar spacing, the traditional lap splicing method, which has been widely used in reinforced concrete constructions, often shows low constructability and difficulties in quality control. Also, lap spliced regions are likely to be over-reinforced, which may not be desirable in seismic design. On the other hand, mechanical splicing methods can offer simple and clear arrangements of reinforcement. In order to utilize the couplers for the ribbed-deformed bars, however, additional screw processing at the ends of reinforcing bars is typically required, which often lead to performance degradations of reinforced concrete members due to the lack of workmanship in screw processing or in adjusting the length of reinforcing bars. On the contrary, the use of screw-ribbed reinforcements can easily solve these issues on the mechanical splicing methods, because it does not require the screw process on the bar. In this study, the mechanical coupler suitable for the screw-ribbed reinforcements has been developed, in which any gap between the reinforcements and sleeve device can be removed by grouting high-flow inorganic mortar. This study presents the uniaxial tension tests on the screw-ribbed reinforcement with the mechanical sleeve devices and the cyclic loading tests on RC columns with the developed coupler. The test results show that the mechanical sleeve connection developed in this study has an excellent splicing performance, and that it is applicable to reinforced concrete columns with a proper confinement by hoop reinforcement.

A Study on Verification of the FRP Grouting Effect using 2D Resistivity Survey and Seismic Refraction Methods (지표물리탐사 기법을 이용한 FRP보강 그라우팅 공법의 보강효과 확인에 관한 사례연구)

  • Park, Jong-Ho;Han, Hyun-Hee;Chae, Hwi-young;Kim, Ik-Hee;Cho, Hyun
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2000.03b
    • /
    • pp.199-206
    • /
    • 2000
  • The grout-effect evaluation of the ground reinforcement technique, which has been widely applied to civil engineering and construction fields, is not established for the guidelines of choosing the efficient evaluation method, and in fact the experts have little effort to determine the reinforcement effect quantitatively. The evaluation of the grout was carried out by experiments on core specimen and drilling, which is impossible to evaluate grout-reinforcement effect quantitatively. This paper presents an example on verification of FRP grout-effect using geophysical prospecting on ground surface, which is 2D resistivity survey that easily visualize survey results with color graphics and seismic refraction method that interprets the subsurface seismic velocity structure.

  • PDF

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

  • Song, Sang-Huwon;Cho, Dae-Sung;Seo, Se-Gwan
    • Geomechanics and Engineering
    • /
    • v.28 no.1
    • /
    • pp.1-10
    • /
    • 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.

A comparative analysis of prediction and measurement for reinforcement effect of face bolts (수치해석 및 계측자료 분석을 통한 막장볼트의 보강효과에 관한 연구)

  • Seo, Kyoung-Won;Kim, Woong-Ku;Baek, Ki-Hyun;Kim, Jin-Woung
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.12 no.5
    • /
    • pp.359-368
    • /
    • 2010
  • Unlike in Korea where steel pipe-reinforced multistep grouting is of commonly used methods for tunnel reinforcement, face bolt method is more widely used due to its better workability and lower construction cost in other countries. In this paper, the effects of both methods after tunnel failure were numerically analyzed and verified based on the oversea construction experiences. As a result it is concluded that the face bolt method may be effective to reinforcement especially when there are some fractured zones developed in the face of tunnel.

Analysis of hydraulic behavior around tunnel after application of cutoff grouting and proposing a method for estimating grouting range (차수그라우팅 적용에 따른 터널주변 수리학적 거동 분석과 그라우팅 적용범위 산정방법의 제안)

  • Joon-Shik Moon
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.26 no.1
    • /
    • pp.79-89
    • /
    • 2024
  • Excessive inflow of groundwater during tunnel excavation not only affects the stability and constructability of the tunnel, but is also one of the main causes of ground settlement due to groundwater level drawdown. The most commonly applied measure against excessive groundwater inflow during tunnel excavation in soil or fractured zone is to reduce the ground permeability coefficient by injecting grout material. Generally, the grouting area is assumed to be same as the plastic zone that occurs during tunnel excavation, but injecting grout material in the area of plastic zone is appropriate only for reinforcement grouting. In order to determine the thickness of cutoff grouting, the amount of reduction in the water permeability coefficient due to the application of cutoff grouting must be considered. In this study, a method for estimating the range of cutoff grouting considering the reduction in permeability coefficient was mathematically derived and evaluated through computer numerical analysis.

Analysis of ground reinforcement effect using fracturing grouting (침투 및 할렬주입에 의한 지반보강 효과에 관한 연구)

  • Lee, J.S.;Lee, I.M.;Chung, H.S.;Lee, D.S.
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.5 no.4
    • /
    • pp.349-360
    • /
    • 2003
  • A practical modeling approach has been proposed in this study to better understand the behavior of penetration grouting which is normally applied to the jointed rock masses to increase the bearing capacity and to reduce the ground water flow into the tunnel. Based on Bingham model together with a steady-state flow of the grout, penetration model is simulated in the commercial package called UDEC and, injection pressure as well as joint thickness are found to be the main parameters to determine the range of grout spread. Another numerical model on fracturing grouting is also suggested and, in this case, the tensile strength as well as cohesion of the rock masses are proven to be the major factors to decide the fracturing mechanism of the rock masses. The reinforcement effect of the grout-reinforced rock masses is calculated from the suggested algorithm on orthotropic material model and it is found that the directional stiffness of reinforced rock masses is increased up to 3 to 4 times compared with original jointed rock masses. Future work will be concentrated on the water control around the tunnel by the grout injection and a model test will also be performed to verify the suggested methods developed in this study.

  • PDF

A Study on the Deformation of Ground by the Low Slump Mortar Grouting (저유동성 몰탈주입 적용지반의 거동에 관한 연구)

  • Do, Jongnam;Lee, Jinkyu;Chun, Byungsik
    • Journal of the Korean GEO-environmental Society
    • /
    • v.11 no.10
    • /
    • pp.5-13
    • /
    • 2010
  • Low slump mortar grouting is widely used in reinforcement of structural foundation and ground improvement in soft ground, and has advantage which construction is possible in insufficient space. However it has been not yet studied sufficiently to estimate the effect of ground improvement in design step and to prove the estimating method. So the method must be developed in order to use the low slump mortar grouting method in various cases. In this study, the field tests were performed in the reclaimed soils to measure the effect of ground improvement. Then it was compared with what was calculated by the existing formula that was formerly suggested. The results show that the value from the formula was similar with the value from the field tests. Also it was proved that the formula was available to estimate the effect of ground improvement in the loose granular soils.

The Development of End-expanded Soil Nailing Method for Ground Reinforcement and its Behavior Characteristics (선단확장형 쏘일네일링 공법 개발과 거동특성 분석)

  • Moon, Hongduk;Jung, Youndug
    • Journal of the Korean GEO-environmental Society
    • /
    • v.14 no.3
    • /
    • pp.19-27
    • /
    • 2013
  • Recently, the natural and man-made slope collapses occur frequently because of sudden heavy rains. So, a variety of slope reinforcement methods have been developed and applied to failure slopes. Soil nailing method usage has been increased because of its workability and economic aspects. This method has been applied in combination with other slope stability methods. Soil nailing method is a kind of combinational structure of steel bar and cement grouting. This method uses skin friction between adjacent ground and cement grouting to stabilize the slope. In this study, End-expanded soil nailing method was developed. This method consists of steel bar and anchor body attached at the tip of the nail. During construction, the anchor body at steel bar tip is settled to the ground through the expanding action. In this study, field pull-out tests were performed for un-grouting soil nailing and grouting soil nailing. From the test results, a wedge force of End-expanded soil nailing method was analyzed. And the behavior characteristics of End-expanded soil nailing were studied.