Pilot Implementation Using Geofoam for Repair of Bridge Approach Slabs

Transcription

1 Pilot Implementation Using Geofoam for Repair of Bridge Approach Slabs Anand J. Puppala, Ph.D., P.E., DGE, F.ASCE Distinguished Professor, Dept. of Civil Engineering Director, Sustainable and Resilient Civil Infrastructure () Center The University of Texas at Arlington (UTA)

2 2 Bump at the End of Bridge 40% TxDOT Bridges Have Bump Issues Annual Maintenance Costs - $7 Millions Seo (2003) Courtesy: URETEK

3 3 Bump at the end of the bridge Foundation Soils Embankment backfill materials 1. Excavation and replacement 1. Geosynthetic reinforcement 2. Preloading surcharge loads 2. Use of MSE wall 3. Vertical drains 3. Grouting 4. Stone columns 4. Use of lightweight fill materials. 5. Deep soil mixing others others

4 4 Lightweight Materials Use of lightweight fill materials for mitigating bridge approach settlement:

5 5 Lightweight Materials Densities and approximate costs of various lightweight fill materials (FHWA NHI ) Materials Density Approximate cost kg/m 3 lb/ft 3 $/m 3 $/ft 3 EPS geofoam 12 to to to to 2.4 Cellular (foamed) concrete 320 to to to to 1.6 Shredded tires 600 to to to to 0.8 Expanded shale and clay 600 to to to to 1.6

6 6 EPS Geofoam Expanded Polystyrene (EPS) Geofoam: ASTM D-4439: a block or planar rigid cellular foamed polymeric material used in geotechnical engineering applications. It has been widely used around the world as a fill material for more than 30 years.

7 7 EPS Geofoam Advantages of EPS Geofoam: About 100 times lighter than soils. At least 20 to 30 times lighter than other lightweight fill alternatives. Easy to handle Expedites construction process Limited labor

8 8 EPS Geofoam Advantages of EPS Geofoam: About 100 times lighter than soils. At least 20 to 30 times lighter than other lightweight fill alternatives. Easy to handle Expedites construction process Limited labor

9 9 Implementation of EPS Geofoam Location: US 67 bridge over SH 174, Johnson County, Cleburne, Texas

10 10 Implementation of EPS Geofoam Bump at the end of the bridge: Test Section - US 67 over SH 174 in Johnson County, Texas Abutments supported by drilled shaft foundation More than 17 in. of settlement observed since construction in 1995

11 11 Geofoam Construction EPS 22 geofoam blocks: top 6 ft depth Geofoam installation period: 3-4 days Test section construction period: January February 2012

12 12 Geofoam Installation Process of EPS geofoam installation

13 13 Geofoam Lightweight Fill Material Instrumentation- Horizontal Inclinometers, Pressure Cells PC #1 PC #2 PC #3 PC #4

14 14 Site Visit and Data Collection The site visits have been conducted at least once a month from January During the visit, the data from horizontal inclinometers and pressure cells are measured and recorded.

15 15 Site Visit and Data Collection Cumulative Displacement (in ) from 1/30/2012 Cumulative Displacement (in ) from 1/30/ US 67 _ Length of inclinometer casing in feet US 67 _ Len th of inclinometer casin in feet 01/30/12 02/07/12 02/14/12 03/06/12 04/18/12 05/23/12 06/20/12 07/20/12 08/29/12 11/30/12 12/21/12 01/13/13 02/17/13 03/11/13 04/13/13 05/20/13 06/18/13 07/19/13 08/21/13 09/19/13 10/18/13 12/05/13 01/16/14 02/14/14 03/21/14 04/18/14 05/23/14 06/17/14 07/18/14 08/15/14 01/30/12 02/07/12 02/14/12 03/06/12 04/18/12 05/23/12 06/20/12 07/20/12 08/29/12 11/30/12 02/17/13 03/11/13 04/13/13 05/20/13 06/18/13 07/19/13 08/21/13 09/19/13 10/18/13 12/05/13 01/16/14 02/14/14 03/21/14 04/18/14 05/23/14 06/17/14 07/18/14 08/15/14 Cumulative Displacement (in ) from 1/30/ US 67 _ Cumulative Displacement (in ) from 1/30/ Len th of inclinometer casin in feet US 67 _ Length of inclinometer casing in feet 01/30/12 02/07/12 02/14/12 03/06/12 04/18/12 05/23/12 06/20/12 07/20/12 08/29/12 11/30/12 01/13/13 02/17/13 03/11/13 04/13/13 05/20/13 06/18/13 07/19/13 08/21/13 09/19/13 10/18/13 06/17/14 07/18/14 08/15/14 01/30/12 02/07/12 02/14/12 03/06/12 04/18/12 05/23/12 06/20/12 07/20/12 08/29/12 11/30/12 01/13/13 02/17/13 03/11/13 04/13/13 05/20/13 06/18/13 07/19/13 08/21/13 09/19/13 10/18/13 12/05/13 01/16/14 02/14/14 03/21/14 04/18/14 05/23/14 06/17/14 07/18/14 08/15/14

16 16 Site Visit and Data Collection 8 6 Pressure (psi) 4 2 PC #1 PC #2 0 Mar-15 Apr-15 May-15 Jun-15 Jul-15 Aug-15 Time (Month-Year) The data presented in the plots was collected from March 2015 PC #1 and PC #2 were installed horizontally at 2 ft. (0.6 m) and 8 ft. (2.4 m) under the pavement surface.

17 17 Analysis of Field Data Prediction of a Long Term Settlement of the Test Embankment: Predicted from the collected field data. Using Hyperbolic method (Lin and Wong, 1999). The hyperbolic relationship between the settlement and time: t = α + β(t) or S = t S (α+ ββ) t = time from the start of embankment fill (days); S = measured settlement as any specific time (mm); β = gradient of the straight line between t and t S ; and α = intersection of the straight line on the t S axis.

18 18 Analysis of Field Data Prediction of a Long Term Settlement of the Test Embankment: By plotting the data with the function of time-settlement ratio, the values of β and α can be determined. Time/Settlement (days/mm ) Time da s Substituting β and α back into the Equation S = t (α+ ββ), the settlement at several times can be calculate and the plot between the settlement and time can be provided.

19 19 Prediction of Long Term Settlement 0. 0 Time ( days ) Settlement (in. ) mm The total settlements of 1.42 in. and 1.50 in. are predicted to occur at 10 year and 20-years intervals. 40

20 20 Numerical Modeling of Geofoam Embankment Geometry of the Test Embankment Section: Material Properties: Properties of the embankment fill and foundation soil were derived from the laboratory test results. Properties of EPS 22 geofoam provided in ASTM D were used.

21 21 Numerical Modeling of Geofoam Embankment System Results of the Numerical Modeling: Vertical Displacement (inch) Time ( days ) Vertical Dis lacement mm Contours of the total vertical displacement on the EPS geofoam embankment model after full dissipation of pore pressure. The vertical displacement time plots at points A, B, C, D, and E.

22 22 Development of Design Charts Design charts to evaluate minimum thickness of EPS geofoam layer S u = FF [ σ pppppppp + σ ttttttt + σ ffff mmmm ] σ pppppppp = σ o, pppppppp W+ H EEE. W σ ttttttt = σ ffff mmmm = σ o, ttttttt W W+ H EEE. γ EEE A EEE + γ ffff ssss A ffff ssss W+2 SSSSS H EEE. A EEE = W + SSSSS H EEE H EEE A wwwww eee. = W + 2 SSSSS H pppp. + SSSSS H EEE. H EEE. A ffff ssss = A wwwww eee. A EEE Minimum Thickness of EPS Geofoam Layer ( ft) Undrained Shear Strength, S u (kpa ) Embakment Height = 50 ft Top Width of Embankment = 76 ft FS = FS = FS = FS = , 000 1, 250 1, 500 1, 750 2, 000 2, 250 2, 500 2, Minimum Thickness of EPS Geofoam La er m Undrained Shear Stren th, S u psf

23 23 Development of Design Charts Design charts to evaluate minimum thickness of EPS geofoam layer (Bearing capacity controls the height of Geofoam) Comparisons of the thickness of EPS geofoam layer

24 Long Term Assessments 24

25 Long Term Assessments 25

26 26 TxDOT: Richard Williammee, Jimmy Si, Wade Blackmon RTI Office Joe Adams, Sonya Badgely and Wade Odell UTA Geotech Research Group Acknowledgements