Development and Application of High Strength FRP Pipes as Grouted- Reinforcing Members in Slope and Tunnel KSCE Annual Conference and Civil Expo 2004 Daewon Soil Co. Ltd., Korea

DAEWON SOIL CONSTRUCTION AND ENGINEERING TABLE OF CONTENTS 1.Introduction 2.Development of FRP Pipe 3.FRP Reinforced Grouting Method 4.Case Histories of FRP Reinforcement in Slope and Tunnel 5.Conclusions

DAEWON SOIL CONSTRUCTION AND ENGINEERING Reinforcing Members made of Steel Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions Soil Nailing Rock Bolt in NATM  Various reinforcing methods such as soil nailing, micro pile, rock bolt, RPUM (Reinforced Protective Umbrella Method), etc. are applied to the tunnels and slopes constructed in incompetent ground  Reinforcements used in reinforcing methods to stabilize the tunnels and slopes have been mainly made of steel. Micro-pile

DAEWON SOIL CONSTRUCTION AND ENGINEERING Disadvantages of Steel Reinforcements Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Corrosion problem Corrosion ratio in ground: 1mm/year normally 10mm/year in aggressive soil  Handling Problem Unit weight of steel reinforcement is normally 3 ~ 6 kg/m Length of reinforcement is usually more than 6m

DAEWON SOIL CONSTRUCTION AND ENGINEERING Disadvantages of Steel Reinforcements Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions Section of 3-Arch Tunnel in a Subway Project Section of KTX Project  Temporary tunnel face reinforcement should be cut when the tunnel face moves forward

DAEWON SOIL CONSTRUCTION AND ENGINEERING Cross Section of FRP Reinforcement Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Tubular Section D = 76mm, P = 440mm, I = 814,112 mm 4  Solid Section D = 41mm, P = 130mm, I = 138,709 mm 4  Sectional Properties  Packer System for Pressure Grouting

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  4 Types of Manufacturing Methods studied Type 1: Pultrusion Process Type 2: Filament Winding Process Type 3: Wrapping Process of Unidirectional Mat (UDMAT) Type 4: UDMAT + Filament Winding Process Pultrusion ProcessFilament Winding ProcessUDMAT

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Tensile & Flexural Test on 4 Types of FRP Pipe - Test Sample FRP Pipe for Tensile and Flexural Test 100cm long FRP pipe Both ends of pipe are filled with a high strength cement mortar to be gripped by 250 tonf capacity of UTM

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Tensile & Flexural Test on 4 Types of FRP Pipe - Setup of Testing Tensile Test UTM having capacity of 250 tonf Load cell and LVDT used to monitor the load and displacement Flexural Test

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Tensile Test Results (Unit: tonf) Type 1: 14.3/11.0/11.6 Type 2: 14.5/9.0/slippage Type 4: 22.5/18.7/20.9 Type 3: 11.3/10.0/9.4

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Summary of Tensile Test Results →Ultimate load of Type 4 is about 2 times higher than others Pipe Type Inner diameter (mm) Outer diameter (mm) Ultimate Load (tonf) Average (tonf) Pultrusion /11.0/ Filament Winding /9.0/slippage11.7 Unidirectional Mat /10. 0/ UDMAT + Filament Winding /18.7/

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Flexural Test Results (Unit: tonf) Type 1: 1.5/1.2/1.5 Type 2: 3.6/3.4/4.0 Type 4: 4.8/5.6/5.6 Type 3: 2.4/2.9/2.7

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Summary of Flexural Test Results →Ultimate load of Type 4 is about 2 ~ 4 times higher than others Type of specimens Test length, l (cm) Outer diameter, d (cm) Ultimate load, p (kgf) Average (kgf) Pultrusion ,504/1,256/1, Filament Winding ,670/3,470/4, Unidirectional Mat ,450/2,944/2, UDMAT + Filament Winding ,816/5,620/5,

DAEWON SOIL CONSTRUCTION AND ENGINEERING Manufacturing Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Conclusions for Manufacturing Method It is not always true that Type4 is the best method because the manufacturing cost of Type4 is higher than others. But the strength of Type4 is 2 times bigger than others, while the cost of that is less than 2 times. Also in actual geotechnical application, the cost of drilling hole is involved. As the pipe becomes stronger, the number of pipes becomes smaller and the drilling cost becomes less.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Concept of FRP Reinforced Grouting Method Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Concept of FRP Reinforced Grouting Method In loose/colluvial soils or highly fractured rocks, the arching effect between reinforcements is not guaranteed unless the space between reinforcements is small enough. In this case it will be more economical to improve ground itself instead of reducing the space between reinforcements. That is the reason why the pressure grouting is used. FRP Reinforced Grouting Method = FRP Pipe + Pressure Grouting

DAEWON SOIL CONSTRUCTION AND ENGINEERING Construction Sequence Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Construction Sequence of FRP Reinforced Grouting Method 1 st Step : Drilling 2 nd Step: Installation of FRP Pipe and Caulking 3 rd Step: Sealing 4 th Step: Grouting

DAEWON SOIL CONSTRUCTION AND ENGINEERING Construction Sequence Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Construction Sequence: 1 st Step - Drilling A hole with diameter over than 125mm is drilled by drilling machine.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Construction Sequence Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Construction Sequence: 2 nd Step – Installation of FRP Pipe & Caulking The FRP pipe and sealing hose are inserted into the hole. Then the entrance of drilled hole is caulked for the annulus between drilled hole and FRP pipe to be filled by sealing admixture through the sealing hose.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Construction Sequence Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Construction Sequence: 3 rd Step - Sealing Sealing admixture is injected through sealing hose to fill the annulus between drilled hole and FRP pipe. The purpose of sealing is to prevent the grout materials from flowing toward the entrance of the hole.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Construction Sequence Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Construction Sequence: 4 th Step - Grouting Grouting is then injected inside the FRP with some pressure relevant to surrounding ground by injection packer system.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Shear Test Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Shear Test on the Four Types of Material Mostly shear resistance is mobilized along the failure surface. Laboratory shear test was carried out to find out the reinforcing effect of FRP pipe: ∙Grout material only : A abc ∙FRP pipe only: A b ∙Inner-grouted FRP pipe: A b + A c ∙Grouted body reinforced with FRP pipe: A a +A b +A c Dia. of Drilled hole = 105mm Dia. of Grouted body = 154mm

DAEWON SOIL CONSTRUCTION AND ENGINEERING Shear Test Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Shear Test: Setup of Shear Testing Loading Shear Box Sample

DAEWON SOIL CONSTRUCTION AND ENGINEERING Shear Test Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Results of Shear Test Grouting: 6,660 kgf FRP Pipe: 3,200 kgf Grouted Body + FRP: 9,000 kgf Inner-grouted FRP: 3,500 kgf

DAEWON SOIL CONSTRUCTION AND ENGINEERING Shear Test Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Summary of Shear Test Results AreaRemarks A abc = cm 2 total area = A a + A b + A c A a = cm 2 grout A b = 6.60 cm 2 FRP pipe A c = cm 2 inside grout SampleAreaMeasuredCalculated GroutA abc 6,660kgf S cem = P cem / A abc = 43.26kgf/ ㎠ FRP PipeAbAb 3,200kgf- FRP Pipe + Inside groutA b + A c 3,500kgfP FRP + A c × S cem = 3,665kgf Composite (FRP + grout)A a + A b + A c 9,000kgfP FRP + (A a + A c ) × S cem = 9,574kgf →FRP Pipe will increase the shear strength of grouted body by 35%.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Site Application Statistics Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Application Statistics Total number of slope and tunnel stabilizing projects: 75 projects ∙Slope : 63 projects (1999 ~ 2003) ∙Tunnel : 12 projects (2000 ~ 2003) ∙Minimum length: 4.0m ∙Maximum length: 20.0m ∙6.0m ~ 10.0m : 68% ∙Minimum spacing: 1.5m ∙Maximum spacing: 3.0m ∙2.0m ~ 2.5m : 60%

DAEWON SOIL CONSTRUCTION AND ENGINEERING Case of Slope Stabilization Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Geological (OO Bridge Approach Road Site) Composed of Cretaceous sedimentary rocks Having complicated faults and multiple joints Mainly featured by tightly spaced bedding planes The dip angle of bedding plane is generally gentle along with overall plane orientation of N80W/12SW ~ N80W/26SW.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Case of Slope Stabilization Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Reinforcing Layout 10m long FRP pipes, square layout of 2 rows having 20 pipes in each row, with 2.5m spacing 8m FRP pipes of 4 rows having 37 pipes in each row, with 2.5m spacing

DAEWON SOIL CONSTRUCTION AND ENGINEERING Case of Tunnel Stabilization Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Geological (OO-OO National Road Expansion Site) Composed of granitic gneiss and gneissic granite as basal rocks with thin intercalation of limestone Especially the location of collapse is composed of fractured fault having foliations and joints. Shear zone of width 4 ~ 40m crosses the tunnel alignment and clayey mineral containing 3 ~ 4cm smectite exists at fault plane.

DAEWON SOIL CONSTRUCTION AND ENGINEERING Case of Tunnel Stabilization Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions  Reinforcing Layout ∙Northbound: C.T.C=.5m(1 row), 1.0m(2 rows), length=28m, angle=2 o ∙Southbound: C.T.C=.5m(1 row), 1.0m(2 rows), length=20m, angle=2 o ∙FRP dimension: Outer diameter=60mm, thickness=5mm

DAEWON SOIL CONSTRUCTION AND ENGINEERING Conclusions Introduction / Development / FRP Reinforced Grouting Method / Case Histories / Conclusions Glass fiber reinforced plastic (FRP) pipe was developed as reinforcing member to substitute steel member and has been widely used in stabilizing slopes and tunnels because of its advantages: light weight, high resistance to oxidation, high strength, etc. Both tubular and solid sections were considered and concluded tubular section more economical. From the tests on four types of manufacturing methods, UDMAT + filament winding process gives 2~4 times higher strength than others. FRP Reinforced Grouting Method was developed to stabilize slopes and tunnels in incompetent ground and has been successfully executed since 1999 in Korea.