• Title/Summary/Keyword: Grouting

Search Result 730, Processing Time 0.031 seconds

The State-of-the-Art of Geophysical Exploration Technology applied to Site Characterization in Civil Engineering and Construction in Japan (일본에서의 토목${\cdot}$건설 지반조사를 위한 물리탐사 활용 현황)

  • Park, Sam-Gyu;Kim, Hee-Joon
    • 한국지구물리탐사학회:학술대회논문집
    • /
    • 1999.08a
    • /
    • pp.1-20
    • /
    • 1999
  • In Japan, geophysical exploration methods have been widely applied to civil engineering and construction fields for a long time. In particular, seismic refraction has long played a significant role in geotechnical site investigations for tunnels, dams and landslides. However, our growing interest on the social and natural environment makes the methods available and its application fields diversify. Digital technologies such as personal computer have revolutionized our ability to acquire large volumes of data rapidly, and to produce more reliable results for subsurface image. Also, color graphics easily visualizes survey results In a more understandable manner, These days geophysical methods are essential to assessing grouting effects, predicting the front of tunnel cutting face, monitoring the movement, pollution and purification process of groundwater. Now three-dimensional exploration techniques have developed for the site characterization in civil engineering and construction needs.

  • PDF

A Study on the Groundwater Effects in the Design of Tunilel Lining (배수형 터널내 과다유입수가 터널의 안정에 미치는 영향)

  • Cheon, Byeong-Sik;Choe, Song-Am;Nam, Sun-Seong
    • Geotechnical Engineering
    • /
    • v.11 no.4
    • /
    • pp.125-140
    • /
    • 1995
  • Generally, the groundwater pressure is not considered in the design of concrete lining of bottom drainage tunnel. This design method implies that the phreatic surface is drawdown to the bottom of tullnel. When tile groundwater is continually supplied without changing of groundwater table, there is a possibility at which the groundwater pressure acting on the tunnel lining after the completion of tunnel. Therefore, the safety of tunnel lining must be checked in this case. In this paper, the stability of bottom drainage tunnel which is affected by groundwater discharge is analzed by using of the Finite Element Method at the 2 sections of subway where the groundwater level has a tittle change during the construction. As the result of analysis, the grouting for the water tightness and the permanent monitoring system of tunnel are required for maintaining of long-term stability of bottom drainage tunnel for the case of groundwater plassure acting on the tunnel lining is greater than that of design stage.

  • PDF

Pullout Characteristics of End Fixed Nails (양단정착형 쏘일네일링의 인발특성)

  • Lee, Bongjik;Kim, Josoon;Lee, Jongkyu
    • Journal of the Korean GEO-environmental Society
    • /
    • v.8 no.4
    • /
    • pp.5-11
    • /
    • 2007
  • In this study, several pullout tests were carried out under various field conditions to evaluate the pullout force of the end fixed nails. Pullout resistance force, displacement and friction force between the grouting and nail were measured in end fixed nails installed in soft rock, weathered rock and weathered soil. Furthermore, the field test were also carried out under the same condition using the conventional type nails. Based on the test results, it is concluded that the end fixed nails showed larger ultimate resistance force compared with conventional types nails, approximately two times in weathered soil and 1.6 times of weathered rock, respectively. The skin friction is also increased in end fixed type about 1.8~3.0 times. Finally, it is concluded in the base of the force transfer properties that using the end fixed nails could decrease the displacement and show a uniform resistance in entire length of nails.

  • PDF

Case Study on the Tunnel Collapse at the Shallow Depth (NATM터널 저토피 구간에서의 막장붕락 사례연구)

  • Baek Ki-Hyun;Roh Jong-Ryun;Kim Yong-Il;Cho Sang-Kook;Hwang Nag-Youn
    • Tunnel and Underground Space
    • /
    • v.15 no.2 s.55
    • /
    • pp.102-110
    • /
    • 2005
  • ○ ○ tunnel that is located at Iksan - Jangsu freeway ○ ○, has collapsed during construction at the valley with shallow depth. Although, the site investigations, such as TSP, drilling exploration and so of indicated the presence of discontinuities in this section. The RMR was upgraded and the construction were carried out because that not only actual rock qualities were relatively good during construction but also the tunnel foe was stabilized. However, the tunnel was collapsed at the same time blasting of full face, and surface and underground water was infiltrated due to the settlement of the upper part of the tunnel face. To restore the collapsed section, 3-d tunnel stability analysis was performed and suitable reinforcement methods were chosen. The cavity of the upper tunnel face was stabilized by means of UAM and ALC injection. And the settlement was restored using L.W grouting method.

Stability Analysis on the Substructure of Abutment in Limestone Basin (석회암층 교대 하부 구조물의 안정성 해석)

  • 최성웅;김기석
    • Tunnel and Underground Space
    • /
    • v.12 no.2
    • /
    • pp.120-129
    • /
    • 2002
  • Natural cavitied were found at shallow depth during construction of a huge bridge in Cambro-Ordovician Limestone Basin in the central part or Korea. The distribution patterns of cavities in this area were investigated carefully with a supplementary field job such as a structural geological survey, a geophysical survey, and a rock mechanical test in laboratory or field. A structural geological mapping produced a detail geological map focusing the route of the Proposed highway. It suggested that there were three faults in this wet and these faults had an influence on the mechanism of natural cavities. Among many kinds of geophysical surveys, an electrical resistivity prospecting was applied first on the specific area that was selected by results from the geological survey. Many evidences far cavities were disclosed from this geophysical data. Therefore, a seismic tomography was tested on the target wet which was focused by results from the electrical resistivity Prospecting and was believed to have several large cavities. A distinct element numerical simulation using the UDEC was followed on the target area after completing all of field surveys. Data from field tests were directly dumped or extrapolated to numerical simulations as input data. It was verified from numerical analysis that several natural cavities underneath the foundation of the bridge should be reinforced Based on the project result, finally, most of fecundations far the bridge were re-examined and the cement grouting reinforcement was constructed on several foundations among them.

A Case Study on the Design of Tunnel Excavation in Geological Anomalies (터널굴착시 지질이상대 통과방안 설계사례 연구)

  • Yoo, Joung-Hoon;Kim, Yang-Kyun;Chung, Chul-Hwa
    • Tunnel and Underground Space
    • /
    • v.21 no.5
    • /
    • pp.341-348
    • /
    • 2011
  • As a result of the detailed site investigation performed for the design of a 4.3 km long tunnel, geological anomalies of four fault zones and a rock boundary were discovered on the tunnel route. Most of all, it was confirmed that pyrite, which may corrode steel material, is contained inside the geological anomalies, and pressured ground water flows out of the fault fractured zone. To overcome these geological conditions, antisulfur concrete for the concrete lining and anticorrosive swelling rock bolts are designed in the pyrite-containing sections. For the sections where a great amount of groundwater outflows, water blocking methods including grouting are applied according to the result of numerical analyses on the seepage. In addition, since the past earthquakes occurred around Korea have take place mainly near fault zones, seismic analyses were performed based on the Soil-Structure Interaction (SSI) concept and the strength of concrete tunnel lining is designed to be 27 MPa from 24 MPa in order to reinforce the tunnel structure.

A case study on asymmetric deformation mechanism of the reserved roadway under mining influences and its control techniques

  • Li, Chen;Wu, Zheng;Zhang, Wenlong;Sun, Yanhua;Zhu, Chun;Zhang, Xiaohu
    • Geomechanics and Engineering
    • /
    • v.22 no.5
    • /
    • pp.449-460
    • /
    • 2020
  • The double-lane arrangement model is frequently used in underground coal mines because it is beneficial to improve the mining efficiency of the working face. When the double-lane arrangement is used, the service time of the reserved roadway increases by twice, which causes several difficulties for the maintenance of the roadway. Given the severe non-uniform deformation of the reserved roadway in the Buertai Coal Mine, the stress distribution law in the mining area, the failure characteristics of roadway and the control effect of support resistance (SR) were systematically studied through on-site monitoring, FLAC 3D numerical simulation, mechanical model analysis. The research shows that the deformation and failure of the reserved roadway mainly manifested as asymmetrical roof sag and floor heave in the region behind the working face, and the roof dripping phenomenon occurred in the severe roof sag area. After the coal is mined out, the stress adjustment around goaf will happen to some extent. For example, the magnitude, direction, and confining pressure ratio of the principal stress at different positions will change. Under the influence of high-stress rotation, the plastic zone of the weak surrounding rock is expanded asymmetrically, which finally leads to the asymmetric failure of roadway. The existing roadway support has a limited effect on the control of the stress field and plastic zone, i.e., the anchor cable reinforcement cannot fully control the roadway deformation under given conditions. Based on obtained results, using roadway grouting and advanced hydraulic support during the secondary mining of the panel 22205 is proposed to ensure roadway safety. This study provides a reference for the stability control of roadway with similar geological conditions.

Safety analysis for the tunnel adjacent to the pier (교각에 근접한 터널의 안정성 평가)

  • Lee, Sun-Bok;Yoon, Ji-Son
    • Journal of the Korean Geophysical Society
    • /
    • v.7 no.4
    • /
    • pp.313-324
    • /
    • 2004
  • The finite element method and statistics of the convergence measurement are useful method of the stability analysis of the tunnel adjacent to the pier. It is the purpose of the this case study to certificate of validity of the application of those methods. The safety of the pilot tunnel method and LW pre-grouting has been evaluated from the FEM analysis. The three-dimensional finite element method is carried out for the decision of the level of stress redistribution at the two-dimensional numerical analysis. An analysis of the convergence is carried out by the estimation of preceding convergence at tunnel excavation. F-examination is applied for this estimation. As results of that analysis, The F-value is from 10.81 to 158.74 and the coefficient of determination is from 0.82 to 0.99. An analysis of convergence is carried out by using regression analysis. Consequently, it is shown that the convergence can be modeled as following function C(t) = a[1-exp(-bt)].

  • PDF

A Study on Reinforcement Method of Reinforced Soil Retaining Wall Through Field Experiment (보강토옹벽의 배부름현상 분석 및 보강 방법에 대한 실험적 연구)

  • Lee, Won-Hong;Mun, Byeong-Jo;Lee, Seuong-Yeol
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.23 no.4
    • /
    • pp.103-112
    • /
    • 2019
  • This study proposes a system to control the bulging phenomenon occurring in the reinforced earth retaining wall and to evaluate the reliability of the system by field experiment. In this study, drainage facilities were not installed in order to induce reinforcement earth retaining wall bulging, and the bulging was induced by rainfall. The induced bulging displacement exceeded the horizontal displacement criterion during the construction of FHWA. The retaining wall block was drilled and grouting was performed by inserting the nail into the drilling hole. The wire mesh is installed on the reinforcing surface and the head of the nail is connected horizontally so that the blocks of the reinforcing earth retaining wall can be supported with each other. In order to protect the reinforcements, the reinforcement surface was closed with shotcrete and a measuring device was installed to detect the progress of the displacement. After the reinforcement, the bulging were not found to progress any more, confirming the reliability of the system.

Development of Reinforcement Grout Materials Using Reinforcing Fiber and Blast Furnace Slag Powder (보강섬유와 고로슬래그 미분말 함유량에 따른 차수그라우트재 개발)

  • Seo, Hyeok;Kim, Daehyeon
    • Journal of the Korean Geosynthetics Society
    • /
    • v.18 no.3
    • /
    • pp.101-112
    • /
    • 2019
  • The grouting method is utilized to reinforce and waterproof poor grounds, enhance the bearing capacity of geo-structures damaged from differential settlement. The purpose of this research is to improve the compressive strength and degree of grout using reinforcing fibers and blast furnace slag powder. In this regard, this study has conducted uniaxial compression tests for the specimens with high ratios (higher than 50%) of blast furnace slag powder. The carbon fiber content was increased by 0, 0.5, and 1.0% to coMpare its compressive strength with that of aramid fiber. The uniaxial compressive strength increased with the increase of fiber content and the bridging activity by fiber in cement tended to increase uniaxial compressive strength. Based on the results, it was confirmed that the aramid fiber has a gel time of 14 seconds and the uniaxial compressive strength is more than 3 Mpa coMpared to carbon fiber.