• Title, Summary, Keyword: Reinforced shotcrete

Search Result 79, Processing Time 0.031 seconds

Multiple Polyamide Fiber Reinforced Shotcrete for Railway Tunnel Structure (철도 터널 구조물 시공을 위한 다발형 폴리아미드섬유 보강 숏크리트)

  • Jeon, Joong-Kyu;Chung, Jae-Min;Yoon, Ji-Hyun;Jeon, Chan-Ki
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.1214-1219
    • /
    • 2011
  • Fiber reinforced shotcrete began to be used in tunnel constructions because it facilitates and expedites the construction process, and improves reinforcement properties. As one of the most widely used forms of shotcrete used in tunneling, steel fiber reinforced shotcrete offers excellent strength and ductility and allows quick reinforcement. However, steel fibers tend to lump together in cement matrix, and low levels of water and acid resistance cause corrosion in steel fiber, resulting in cracks and delamination. In particular, rebound and backlash of steel fiber is significantly increased during steel fiber reinforced shotcrete construction, compromising the flexural toughness and quality of shotcrete. In order to resolve the problems associated with steel fiber reinforced shotcrete and improve the application, durability, and cost-effectiveness of shotcrete, this paper proposes methods for manufacturing and constructing tunnels with multiple polyamide fiber reinforced shotcrete. We performed experiments to evaluate the performance of the proposed shotcrete, and the experimental results indicate that the multiple polyamide fiber reinforced shotcrete proposed in this paper offers outstanding performance that meets various construction design criteria.

  • PDF

A development of modification program for steel fiber reinforced shotcrete during design and construction stages (강섬유 숏크리트의 설계 및 시공에 대한 문제점 및 개선방향에 대한 연구)

  • Kim, Sang-Hwan;Youn, Seung-Ki
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • /
    • pp.48-57
    • /
    • 2009
  • The quality control of tunnel support construction is very important to maintain a long term stability of tunnel. Especially, steel fiber reinforced shotcrete should be necessary to investigate practically the condition of quality control in the construction site. In order to perform this study, the design criteria and specifications relevant to steel fiber reinforced shotcrete are reviewed. And the comparison is made between the bearing capacity of the several shotcrete layers, based on the equivalence of the bending moments. Eight tunnel construction sites are also investigated carefully to examine and analyse the characteristics of steel fiber reinforced shotcrete especially including strength and mixing condition of steel fiber. Based on the results, it is founded the items to be improved in the future. In addition, the modification program for the specifications of steel fiber reinforced shotcrete is suggested.

  • PDF

The Strength Characteristic of Shotcrete Reinforced with Improved Shape Steel Fiber (형상을 개선한 강섬유보강 숏크리트의 강도특성)

  • Kim, Sang-Hwan;Park, Inn-Joon;Kim, Ji-Tae
    • Journal of the Korean Geotechnical Society
    • /
    • v.27 no.12
    • /
    • pp.127-136
    • /
    • 2011
  • The laboratory tests were performed to investigate the strength characteristic of shotcrete reinforced with improved shape steel fiber developed in this study. Two different type of tests, the flexural toughness test and the bending strength test, were conducted for analyzing shotcrete strengths using three types of specimens (unreinforced shotcrete, exiting steel fiber reinforced shotcrete, and new concept steel fiber reinforced shotcrete). The results of tests represented the advancement of the strength characteristic of shotcrete reinforced with improved shape steel fiber with respect to that of shotcrete reinforced with existing steel fiber.

Experimental Construction of Polyamide Fiber Reinforced Shotcrete Technology (다발형 폴리아미드섬유 보강 숏크리트 현장 적용성 평가)

  • Yoon, Ji-Hyun;Jeon, Joong-Kyu;Jeon, Chan-Ki;Lee, Soo-Choul
    • Journal of the Korean Recycled Construction Resources Institute
    • /
    • v.7 no.2
    • /
    • pp.78-83
    • /
    • 2012
  • Steel fiber reinforced shotcrete in tunneling construction has some problems in terms of constructability, durability and lots of rebound wastage. In order to resolve these problems, this pater proposes polyamide fiber reinforced shotcrete technology. And this paper presents the results of experimental construction of the polyamide fiber reinforced shotcrete technology. The results of the study are as follows. 1. The polyamide fiber reinforced shotcrete suggested in this paper shows outstanding mechanical performance that meets various Korean tunnel construction design criteria. 2. In addition, the results of experimental constructions show that the polyamide fiber reinforced shotcrete creates less rebound and wasted product than the steel fiber reinforced shotcrete. Based on the above results, it is concluded that the polyamide fiber reinforced shotcrete technology can be used as economical and environmentally friendly construction of tunnel.

  • PDF

Flexural Behavior Evaluation of Two Types Fiber Reinforced Shotcrete using Round Panel Test (원형패널 시험을 활용한 두 종류 섬유 보강 숏크리트의 휨거동 평가)

  • Jeon, Chanki;Jeon, Joongkyu
    • Journal of the Society of Disaster Information
    • /
    • v.11 no.4
    • /
    • pp.607-614
    • /
    • 2015
  • This study evaluated the flexural performance of steel and PP fiber reinfroced shotcrete using round panel test according to ASTM that can consider the actual stress of fiber reinforced shotcrete in tunnel and under ground structures. The results of round panel test are converted to the square panel test results according to the EFNARC. The energy absorptions of each fiber reinforced shotcrete were classified according to the EFNARC toughness classification. Test results show that the PP fiber reinforced shotcrete has better flexural performance compared with the steel fiber reinforced shotcrete.

An Experimental Study on the Mechanical Properties and Rebound Ratios of SFRS with Silica Fume

  • Son, Young-Hyun;Chai, Won-Kyu
    • International Journal of Safety
    • /
    • v.8 no.2
    • /
    • pp.20-25
    • /
    • 2009
  • In this study, an experiment in the field was performed to analyze the mechanical properties and the influence of steel fiber and silica fume on the rebound ratios of shotcrete. The experimental parameters which are the reinforcing methods (steel fiber, wire mesh), steel fiber contents (0.0%, 0.5%, 0.75%, 1.0%), silica fume contents (0.0%, 10.0%), layer thickness (60 mm, 80 mm, 100 mm), and the placing parts (sidewall, shoulder, crown) were chosen. From the mechanical test, it was found that the flexural strength and toughness is significantly improved by the steel fiber and/or silica fume. According to the results for the side wall in this test, the larger the fiber contents are in case of steel fiber reinforced shotcrete, the less the rebound ratios are within the range of 20-35%, compared to the wire mesh reinforced shotcrte. And also, the reduced rebound ratios were very larger in using steel fiber reinforced shotcrete with silica fume content of 10%, and these results are true of the shoulder and the crown. respectively.

A Study on the Strength Characteristics and Rebound Ratio with Respect to Injection Pressure of Shotcrete (숏크리트의 강도 특성과 분사압력에 대한 리바운드율 연구)

  • Jeon, Jun Tai;Moon, In Gi;Lee, Yang Kyu
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.39 no.1
    • /
    • pp.115-122
    • /
    • 2019
  • Steel Fiber Reinforced Wet-type Shotcrete improves the quality and stabilizes the tunnel by increasing the shear strength of the natural ground by constructing the concrete which attaches the fresh concrete to the predetermined position from the nozzle. The Steel Fiber Reinforced Wet-type Shotcrete improves and reinforces the strength and dynamic behavior characteristics of concrete to suppress the generation and growth of local cracks by increasing the tensile resistance ability. In addition, Steel Fiber Reinforced Wet-type Shotcrete is a shotcrete that improves tensile strength, bending strength, and crack resistance by dispersing discontinuous short steel fibers evenly in concrete. In this study, compressive strength test and bending strength test of shotcrete of NATM tunnel were measured and rebound reduction rate was measured by varying shotcrete putting pressure to 900 RPM, 1,000 RPM, and 1,100 RPM. Therefore, the data that can be applied to domestic NATM tunnel construction are presented.

A Study on the construction method of reinforced shotcrete using structural synthetic fiber (터널 지보특성 개선을 위한 보강함성섬유 숏크리트공법 연구)

  • Han, Il-Yeong;Kim, Bang-Lae;Won, Jong-Pil
    • 한국터널공학회:학술대회논문집
    • /
    • /
    • pp.259-261
    • /
    • 2005
  • The needs of improving the performance of wet shotcrete has become one of the most important issues in the tunnel field. The aim of this paper is to research the construction method of reinforced shotcrete using structural polymer fiber which exhibits a high quality in toughness and durability for the support of tunnel.

  • PDF

A study on evaluation of flexural toughness of synthetic fiber reinforced shotcrete (구조용 합성섬유 보강 숏크리트 휨인성 평가에 관한 연구)

  • Moon, Kyoung-Sun;Kim, Seog-Jin;Kim, Yeon-Deok;Min, Byeong-Heon;Kim, Sang-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.21 no.3
    • /
    • pp.433-452
    • /
    • 2019
  • This study deals with shotcrete reinforcing performance according to the amount of synthetic fiber (PP fiber) and proper evaluation method. The shotcrete compressive strength, flexural strength and flexural toughness were tested by setting the mixing amounts of steel fiber ($37.0kg/m^3$) and synthetic fiber (PP fiber) as parameters ($5.0kg/m^3$, $7.0kg/m^3$ and $9.0kg/m^3$). Particularly, circular panel flexural toughness test (Road and Traffic Authority, RTA) was performed to evaluate the shotcrete energy absorption capacity. As a result, the compressive strength and the bending strength of the steel fiber reinforced shotcrete were large, but the flexural toughness of the synthetic fibe (PP fiber) reinforced shotcrete was large. Therefore, synthetic fiber (PP fiber) reinforced shotcrete is considered to have a reinforcing effect comparable to that of steel fiber reinforced shotcrete. Analysis of the relationship between the flexural toughness and the energy absorption capacity of synthetic fiber (PP fiber) reinforced shotcrete revealed that the energy absorbing ability is exhibited at a flexural toughness lower than the allowable standard (3.0 MPa). (Class A: 2.55 MPa = 202J, Class B: 2.72 MPa = 282J, Class C: 3.07 MPa = 403J). As a result of this study, it can be concluded that the actual shotcrete support performance can be evaluated by evaluating the support performance of the shotcrete measured at less than the allowable standard (3.0 MPa) at the actual tunnel site.