Development of Pressure Penetrating Pipe(PPP) Pile for Enhancement of Bearing Capacity 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 3/14 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 4/14 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 5/14  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 equipmentsModelManufacturer 5MN Compression testerCCH-5000KNISIMADZU/JAPAN Static data loggerYCAM-500AKYOWA/JAPAN

Durability Performance Test Test object installation 6/14 Hydraulic Pump 500Ton Load Cell Test Object Data Logger

Durability Performance Test Test Results 7/ Load(kN) Repeat Count Load(kN) Repeat Count 500kN 6,667Times Test objectHydraulic Jack(50Ton) Repeat count6,667(cycles)>>1,000 Results - No oil leaking - load of over 500kN induced

Durability Performance Test After test completion 8/14

Load Test Plans Purpose of Load Test 9/14  Load-settlement relationships  Bearing capacity of pile  Load transfer analysis Test# of pileTimes Load test18 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 10/14

Load Test Plans Considering Factors – Strain gage 11/14 Strain gage Concrete Soil Welding Plate(Aluminum) Welding Spacer Connecting lines Plan 1 Plan 2Plan 3 Φ t, L=1m Pipe pile Φ t, L=1m Pipe pile Φ t, L=1m Pipe pile

Load Test Plans Considering Factors – Strain gage 12/14 Plan 1Plan 2Plan 3 Detailed Plan Price of strain gauge400,000 won25,000 won200,000 won Processing cost of pile25,000 won40,000 won20,000 won Damage from weldingLittle 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 13/14 Hydraulic Jack (50.0tf) Concrete Soil Pressure Plate Install Plate Pipe Pile Plan 1 Plan 2Plan 3 Pipe Pile Φ t

Summary & Further study  The PPP pile method has many advantages compared to the existing construction method. However, there are disadvantages and not many construction 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 completion.  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 14/14  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