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FHWA-RD-99-194
An Instrumented Multiple deployment Model Pile (MDMP) was developed for monitoring pile/soil interaction including pile capacity gain with time. The MDMP instrumentation and field installation allows to accurately obtain parameters applicable to full scale pile design. The MDMP was successfully deployed in Newbury, MA. The obtained results demonstrate the ability to predict the time-dependent behavior of full scale piles and hence to improve the design and construction of driven piles.
This report will be of interest to geotechnical researchers and practitioners dealing with structures involving driven piles.
T. Paul Teng, P.E. |
NOTICE
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification, or regulation.
The U.S. Government does not endorse products or manufacturers. Trade or manufacturers's names appear herein only because they are considered essential to the object of this document.
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9. Performing Organization Name and Address UMASS-Lowell |
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of Infrastructure Research and Development Massachussetts Highway Department |
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16. Abstract A model pile is a calibrated tool equipped with instrumentation capable of monitoring the pile/soil interaction over the pile history. Monitoring includes the installation, pore pressure dissipation combined with consolidation and soil pressure equalization, and ultimately the pile behavior under loading and failure. The model pile installation and soil-structure interaction simulate the actual field conditions of full-scale piles. As such, the obtained information can be utilized directly (e.g., skin friction) or extrapolated (e.g., pore pressure dissipation time) to predict the soil's response during full-scale pile installation. The Multiple Deployment Model Pile (MDMP) was developed as an in situ tool for site investigations. The MDMP instrumentation is capable of monitoring the pile/soil interaction throughout the life cycle of a driven pile: (1) dynamic force and acceleration readings at the pile top and along the pile during driving; (2) pore water pressure and radial stresses during equalization; and (3) skin friction, end-bearing resistance, and local (subsurface) displacement during static loading. These measurements allow the observation of pile capacity gain (a.k.a. "set-up" or "freeze") and accurately monitor the load-transfer relations. The MDMP was successfully deployed twice in Newbury, MA during March 1996. The obtained dynamic measurements allowed the evaluation of the pile's static capacity and clarified the difficulties associated with dynamic analysis of small-scale penetration. Pile capacity gain with time was examined based on normalization procedures developed by Paikowsky et al. (1995). The excess pore water pressure dissipation, variation in radial effective stresses, and pile capacity gain with time were determined for the two tests. The obtained results show that the MDMP is capable of providing accurate soil-structure interaction relations during static load testing. The measurements indicate a complex mechanism governing capacity gain that combines pore pressure dissipation and radial stress redistribution over time. These findings are used to predict the time-dependent behavior of full-scale instrumented piles and to re-evaluate the capacity gain phenomenon. The obtained results explain some unanswered questions and allow the development of procedures incorporating pile capacity gain in design and construction. |
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Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
2. MODEL PILES FOR FIELD TESTING - REVIEW
2.2. The Cone Penetration Test (CPT) Model
2.3. The Piezo-Lateral Stress (PLS) Cell
2.4. The Grosch and Reese (G&R) Model Pile
2.5. The Norwegian Geotechnical Institute (NGI) Model Pile
2.6. The X-Probe and the 3-Inch Model Piles
2.7. The In Situ Model Pile (IMP)
2.8. The Imperial College Pile (ICP)
3. THE MULTIPLE DEPLOYMENT MODEL PILE (MDMP)
3.3. Analysis of the MDMP Loading Conditions
3.3.2. Static Capacity Analysis
3.3.4. Summary of Load Requirements
3.4. Specifications for Instrumentation and Mechanical Parts
3.4.4. Pore Pressure Transducer
3.4.9. Summary of the Instrumentation Range Requirements
3.5.3. Connector Housing and Mount
3.6.3. Pore Pressure Transducer Calibration
3.6.4. Total Pressure Cell Calibration
3.6.5. Displacement Transducer Calibration
3.6.6. Accelerometer Response During Dynamic Loading
4. MDMP PERIPHERAL TEST ACCESSORIES
4.1. Overview of Peripheral Test Accessories
4.2. Hewlett Packard Data Acquisition System
4.4.2. Power Supply Requirement
4.6.3. Hydraulic Loading System
5. MDMP TESTS AT THE NEWBURY, MA SITE
5.1. Site Overview and Location
5.2. Previous Subsurface Exploration Program Studies
5.3. UMass-Lowell Subsurface Exploration Program
5.3.1. Sampling and Field Testing
5.4. Typical Subsurface Stratigraphy
5.5. Engineering Properties of the Clay at the Newbury Test Site
5.6. Predicted Behavior of the Multiple Deployment Model Pile
5.6.2. Estimated Increase in Pore Pressure Due to Driving
5.6.3. Estimated Time for Excess Pore Water Pressure Dissipation
5.6.4. Estimated Time for Capacity Gain
5.7.3. Testing Procedure for the MDMP during Test NB2
5.7.4. Testing Procedure for the MDMP during Test NB3
6.1. Pore Pressure Measurements
6.1.2. Pore Pressure Results for the MDMP Test NB2
6.1.3. Pore Pressure Results for the MDMP Test NB3
6.1.4. Common Pore Pressure Behavior of the Two Tests
6.2. Radial Stress Measurements
6.3. Load Transfer Along the Friction Sleeve
6.3.1. General Considerations - Initial Reading
6.4. Surface Load Cell Measurements
6.4.2. Heave Measurements During Model Pile Test NB2
6.4.3. Comparison of Surface and Internal Load Cell Measurements
6.5.1. Final Load Testing Sequence
6.6.1. Driving System and Dynamic Measurements
6.6.2. Installation During Model Pile Test NB2
6.6.3. MDMP Restrike During Model Pile Test NB2
6.6.4. Installation During Model Pile Test NB3
6.6.5. Restrike During Model Pile Test NB3
7. ANALYSIS OF THE MDMP TEST RESULTS
7.1. Normalized Pore Pressure Dissipation
7.1.3. Comparison with Other Test Results
7.5. Time-Dependent Radial Stresses
7.9. Shaft Resistance and Design Parameters
7.10. Dynamic Measurements Interpretation
7.10.1. Measured Signals and Wave Mechanics
7.10.2. Capacity Based on the Energy Approach
7.10.3. Capacity Based on CAPWAP Analysis
7.10.4. Capacity Based on the Case Method
7.11. Comparison Between the Static Capacity and the Analyses Based on Dynamic Measurements
8. SUMMARY CONCLUSIONS AND RECOMMENDATIONS
8.1.1. The MDMP Configuration and Specifications
8.1.2. The Newbury Site Testing
Figure 2 Typical Locations of Pore Pressure Measurements for Piezocone Penetrometers
Figure 3 The Piezo-Lateral Stress (PLS) Cell (Morrison, 1984)
Figure 4 Detailed Cross-Section of the Piezo-Lateral Stress (PLS) Cell (Morrison, 1984)
Figure 5 Details of the Axial Load Cell in the Piezo-Lateral Stress (PLS) Cell (Morrison, 1984)
Figure 6 The Grosch and Reese (G&R) Instrumented Model Pile (Grosch and Reese, 1980)
Figure 8 The 7.62-cm (3.0-in) Instrumented Model Pile (Bogard and Matlock, 1985)
Figure 9 The X-Probe (Bogard and Matlock, 1985)
Figure 10 Details of 7.62-cm (3-in) Model Pile Axial Load Cells (after Patent Number 5,259,240)
Figure 11 Details of 7.62-cm (3-in) Model Pile Pressure Instruments (after Patent Number 5,259,240)
Figure 12 Configuration and Instrumentation of the In Situ Model Pile (IMP) (after Lehane, 1992)
Figure 13 The Imperial College Instrumented Model Pile (Bond and Jardine, 1991)
Figure 14 Typical Imperial College Model Pile Instrument Cluster (Bond et al., 1991)
Figure 15 The Surface Stress Transducer (Bond et al., 1991)
Figure 16 The Combined Axial Load Cell and Pore Pressure Unit (Bond et al., 1991)
Figure 17 Typical Configurations of the MDMP
Figure 18 Tip Configurations of the MDMP
Figure 19 Typical Soil Profile for the Boston Area
Figure 20 Hypothetical Soil Profile of Dense Sand
Figure 21 Drop Hammer Configuration Modeled in the Wave Equation Analyses
Figure 22 Photograph of the MDMP Load Cell with Sleeve
Figure 24 Photograph of the Slip Joint with DCDT
Figure 25 (a) Schematic of the Calibration Frame for the MDMP , (b) Photograph of the Calibration Frame for the MDMP
Figure 26 Pressure Instrumentation Calibration Setup
Figure 27 (a) Photograph of the Dynamic Instrumentation Testing Setup
(b) Schematic of the Dynamic Instrumentation Testing Setup
Figure 28 Schematic of the MDMP Data Acquisition System
Figure 29 Hewlett Packard Data Acquisition System (HP DAS)
Figure 30 Pile-Driving Analyzer (PDA) Data Acquisition System
Figure 31 Connection Box, Back Faceplate
Figure 32 Connection Box, Front Faceplate
Figure 33 (a) Schematic of the MDMP Static Load Frame, (b) Photograph of the MDMP Static Load Frame
Figure 34 Newbury Site Locus Plan
Figure 35 Newbury MDMP Site Plan
Figure 36 Representative Soil Stratigraphy at the Newbury MDMP Test Site (Chen, 1997)
Figure 37 Soil Profile of the Newbury Test Site (North-South)
Figure 38 Groundwater Elevations at the Newbury Test Site
Figure 42 Effects of OCR on u/
v'v Aong the Shaft (h/r
7) for r/R=1 (Paikowsky et al., 1995)
Figure 43 Predicted Pore Pressure Dissipation and Capacity Gain for the MDMP at the Newbury Site
Figure 45 Steps for Installation and Testing of the MDMP at the Newbury Site
Figure 46 (a) MDMP Being Driven and (b) Static Load Frame Assembled
Figure 47 Pore Pressure Build-Up and Dissipation With Time for Model Pile Test NB2
Figure 48 Pore Pressure Build-Up and Dissipation With Time for Model Pile Test NB2
Figure 49 Pore Pressure Build-Up and Dissipation With Time for Model Pile Test NB3
Figure 50 Pore Pressure Build-Up and Dissipation With Time for Model Pile Test NB3
Figure 51 (a) Total Radial Stress, rWith Time, MDMP Test NB2
(b) Total Radial Stress, r With Time, MDMP Test NB2 (including a possible adjustment)
Figure 52 (a) Total Radial Stress, rWith Time, MDMP Test NB2
(b) Total Radial Stress, rWith Time, MDMP Test NB2 (including a possible adjustment)
Figure 53 (a) Effective Radial Stress, r' With Time, MDMP Test NB2
Figure 54 (a) Effective Radial Stress, r' With Time, MDMP Test NB2
Figure 56 Internal Load Measurements, MDMP Test NB2
Figure 57 Adjustments to Internal Load Measurements, MDMP Test NB2
Figure 58 Frictional Forces Along the Friction Sleeve for MDMP Test NB2
Figure 59 Shear Transfer Along the Friction Sleeve for MDMP Test NB2
Figure 60 Internal Load Measurements, MDMP Test NB3
Figure 61 Frictional Forces Along the Friction Sleeve for MDMP Test NB3
Figure 62 Shear Transfer Along the Friction Sleeve for MDMP Test NB3
Figure 65 Comparison Between the Surface and the Internal Load Cell Measurements for MDMP Test NB2
Figure 66 Comparison Between the Surface and the Internal Load Cell Measurements for MDMP Test NB3
Figure 74 Blow Count and Energy Delivered Versus Penetration Depth for the Restrike of MDMP Test NB2
Figure 78 Blow Count and Energy Delivered Versus Penetration Depth for the Restrike of MDMP Test NB3
Figure 80 Maximum Dynamic Forces Measured During Installation of MDMP Test NB2
Figure 81 Maximum Dynamic Forces Measured During Restrike of the MDMP Test NB2
Figure 82 Maximum Dynamic Forces Measured During Installation of MDMP Test NB3
Figure 83 Maximum Dynamic Forces Measured During Restrike of MDMP Test NB3
Figure 84 Maximum Dynamic Velocities Measured During Installation of MDMP Test NB2
Figure 85 Maximum Dynamic Velocities Measured During Restrike of MDMP Test NB2
Figure 86 Maximum Dynamic Velocities Measured During Installation of MDMP Test NB3
Figure 87 Maximum Dynamic Velocities Measured During Restrike of MDMP Test NB3
Figure 88 Normalized Excess Pore Pressure and Shear Transfer Gain, Model Pile Test NB2
Figure 89 Normalized Excess Pore Pressure and Shear Transfer Gain, Model Pile Test NB3
Figure 95 Relationships between Shaft Friction, Radial Stress, and Vertical Stress for MDMP Test NB2
Figure 96 Final Load Test for MDMP Test NB2
Figure 97 Final Load Test for MDMP Test NB3
Figure 98 Shear Transfer Along the Friction Sleeve for MDMP Test NB2
Figure 99 Shear Transfer Along the Friction Sleeve for MDMP Test NB3
Figure 105 Surface Force and Velocity Records of the MDMP Test NB2 Restrike, Blow 1
Figure 112 Surface Force and Velocity Records for MDMP Test NB3 Restrike, Blow 2
Figure 127 Typical Configuration of the Modular MDMP
Table 1 Comparison of Various Instrumented Model Piles
Table 2 MDMP Static Load Resistance in Soft BBC (Lower Limiting Case)
Table 3 MDMP Static Load Resistance in Dense Sand (Upper Limiting Case)
Table 4 Dynamic Loads and Accelerations in the MDMP during Easy or Hard Driving
Table 5 Summary of Load Cell Capacity Requirements
Table 6 Summary of the MDMP Required Instrumentation Ranges
Table 8 Top Load Cell Calibration Results
Table 9 Middle Load Cell Calibration Results
Table 10 Bottom Load Cell Calibration Results
Table 11 Dynamic Calibration Results of the MDMP Load Cells
Table 12 Pore Pressure Transducer Calibration Results
Table 13 Total Pressure Cell Calibration Results
Table 14 List of Components as Shown in Figure 28
Table 15 MDMP Data Acquisition and Instrumentation Configuration
Table 16 Sampling Performed at Boring NB1
Table 17 Sampling Performed at Boring NB4
Table 18 Sampling Performed at Boring NB5
Table 19 Sampling Performed at Boring NB2
Table 21 The MDMP Static Load Tests During Test NB2
Table 22 The MDMP Final Loading Sequence During Test NB2
Table 23 The MDMP Static Load Tests During Test NB3
Table 24 The MDMP Final Loading Sequence During Test NB3
Table 27 Initial Adjustments to Internal Load Cell Measurements
Table 28 Average Peak Forces Measured at Three Locations in the MDMP
Table 29 Average Peak Velocity Measured at Three Locations in the MDMP
Table 32 Summary of Gain of Capacity Parameters and Their Comparison to a Large Data Set
Table 34 Shear Transfer Recorded During NB2 Final Load Test
Table 35 Average Shear Transfer Recorded During NB2 Final Load Test
Table 36 Shear Transfer Recorded During NB3 Final Load Test
Table 37 Average Shear Transfer Recorded During NB3 Final Load Test
Table 38 Variations in the Cross-Section / Impedance Between the Drilling Rods and the MDMP218
Table 39 Energy Approach Capacity Predictions for the MDMP
Table 40 Cross-Sectional Areas for CAPWAP Modeling of the MDMP
Table 47 Summary of the MDMP Instrumentation Ranges