Development of Pressure Penetrating Pipe(PPP) Pile for Enhancement of Bearing Capacity
2013.04.17
Do, Eunsu
Seoul National University Geotechnical & Geoenvironmental Engineering Lab
1. Introduction
Contents
2. Durability Performance Test
3. Load Test Plans
4. Summary & Further Study
Introduction
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Concepts of PPP Pile
Method using hydraulic jacking device to penetrate pipe piles by pressure Able to check bearing capacity by pressure of hydraulic jacking device High workability in narrow areas (0.6m x 0.6m x 2m) Small and light penetrating equipment (4 small hydraulic jack + guide steel bar + pressure plate)
Grouting
Introduction
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Advantages No vibration or noise No need to clear near pile after construction Compact jacking devices Construction possible for limited areas Checking of correct pile bearing capacity possible
Disadvantages Not many construction cases Difficulty in penetration when amber or boulders exist
Research Plans Estimation of pile bearing capacity through load tests – Load transfer analysis, base & shaft resistances Assessment of penetration availability according to soil conditions – Check the applied load through load cell
Vibration, Noise, Dust
Durability Performance Test Certification of Test
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Test object: Hydraulic jacking device(50Ton) Test method 1) Method: operate jacking device so a load of over 500kN is induced 2) Target lifetime: 6,667 cycles 3) Velocity: within 30 seconds per cycle 4) Load drop under 500kN or oil leaking should not happen after target lifetime Environment of Laboratory: 25±5℃, 50±25% Test equipments
Test equipments Model Manufacturer5MN Compression
testerCCH-5000KNI SIMADZU/JAPAN
Static data logger YCAM-500A KYOWA/JAPAN
Durability Performance Test Test object installation
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Hydraulic Pump
500Ton Load Cell
Test Ob-ject
Data Logger
Durability Performance Test Test Results
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0
100
200
300
500
400
600
Load(kN)
Repeat Count
0
100
200
300
500
400
600
Load(kN)
Repeat Count
500kN
6,667Times
Test object Hydraulic Jack(50Ton)Repeat count 6,667(cycles)>>1,000
Results- No oil leaking
- load of over 500kN induced
Durability Performance Test After test completion
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Load Test Plans Purpose of Load Test
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Load-settlement relationships Bearing capacity of pile Load transfer analysis
Test # of pile Times
Load test 1 8 times
Plans of Load Test
Weathered rock placed in relatively shallow depths(5~8m)
Test pile installation depth: 10~15m
Load Test Plans Plans of Load Test
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Load Test Plans Considering Factors – Strain gage
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Strain gageStrain gage
Concrete Concrete Concrete
Soil Soil SoilWelding
Plate(Aluminum)
Welding Weld-ingSpacer Connecting
linesConnecting lines
Connecting lines
Plan 1 Plan 2 Plan 3
Φ216.3-12t, L=1mPipe pile Φ216.3-12t, L=1m
Pipe pile Φ216.3-12t, L=1m
Pipe pile
Load Test Plans Considering Factors – Strain gage
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Plan 1 Plan 2 Plan 3
Detailed Plan
Price of strain gauge 400,000 won 25,000 won 200,000 won
Processing cost of pile 25,000 won 40,000 won 20,000 won
Damage from welding Little Little Heat transfer by bolt
Advantages &Disadvantages
- Minimize damage- High cost- Limited depth(30cm)
- Many similar cases- Able to cut and process surface
- Low reliability of data- Minimize effect of stiffness- High cost- Limited depth(30cm)
Load Test Plans Considering Factors – Load Cell
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Hydraulic Jack
Hydraulic Jack Hydraulic Jack(50.0t
f)(50.0tf)
(50.0tf)
Concrete Concrete Concrete
Soil Soil Soil
Pressure Plate
Pressure Plate
Pressure Plate
Install Plate
Install Plate
Pipe Pile
Plan 1 Plan 2 Plan 3
Pipe Pile Pipe PileΦ216.3-12t Φ216.3-12tΦ216.3-12t
Summary & Further study
The PPP pile method has many advantages compared to the existing con-struction method. However, there are disadvantages and not many construc-tion cases.
According to a result of the durability performance test, When a load of 500kN in the hydraulic jack was induced, there are no oil leaking after test comple-tion.
Load test plans were made considering the economic feasibility of strain gage and the installation of load cell. Analysis on load transfer and bearing capacity of piles will be conducted after completion of load test.
Summary
Further study
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Estimation of pile bearing capacity through load tests – Load transfer analysis, base & shaft resistances Assessment of penetration availability according to soil conditions – Check the applied load through load cell