Structural/Hydrologic Design & Maintenance of Permeable Interlocking Concrete Pavement

Transcription

1 Structural/Hydrologic Design & Maintenance of Permeable Interlocking Concrete Pavement David R. Smith, Technical Director Interlocking Concrete Pavement InsCtute, Herndon, Virginia USA William F. Hunt, Ph D PE, Associate Professor North Carolina State University, Raleigh, North Carolina USA

2 PICP Soil Subgrade

3 Structural & Hydrologic Design Installer Qualifications

4 PICP Typical max. lifecme loads: 600,000 18,000 lb ESALs or TI = 8.5 Permeable Interlocking Concrete Pavements, ICPI 2006 ** Strengthen soil subgrade with crushed stone to full frost depth

5 AASHTO Typical ESALs by Road Class Road Class Arterial or Major Streets Design ESALs Urban 7,500,000 Rural 3,600,000 Major Collectors Urban 2,800,000 Rural 1,450,000 Minor Collectors Urban 1,250,000 Rural 550,000 Commercial/MulC- Family Locals Urban 425,000 Rural 275,000

6 Permeable Pavement Design Structural Analysis Hydrological Analysis Pedestrian Use Vehicular Use Time Steps Subgrade Characteristics: M r, CBR, R-Value Traffic Load: ESALs, Traffic Index Design Storm(s) Contributing Area Runoff Determine Surface & Base/Subbase Thickness Surface & Base/ Subbase Properties Infiltration Rate & Volume Through Subgrade Determine Depth of Water & Base/ Subbase thickness Outflow Rate & Volume Through Underdrains Revise Thickness or Adjust Outflow Revise Thickness No Structurally Adequate? Ye s Select the Limiting (Thicker) Cross- Section for Design Ye s Hydrologically Adequate? No

7 Permeable Design Pro Software for PICP Design

8 Define PICP Pavement & Contributing Area

9 Select/Design Pavement Material Properties

10 Traffic Analysis for Structural Design

11 AASHTO Structural Design Analysis

12 Establish Hydrologic Conditions and Design Storms

13 Calculate Total Water In-Flow

14 Select Drainage Parameters and Conditions

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16 Select Base Thickness from Rainfall Event

17 Repeat Analysis to Fine Tune PICP Design Include drain pipes as required

18 Maintenance 18

19 Completely clogged surfaces require restorative vacuum cleaning 19

20 Inspect & vacuum sweep 2x annually with standard equipment - no water d Inspect & vacuum Sweeping only equipment not effective in removing sediment Check infiltration in small areas with water - Use ASTM C1701 as needed 20

21 Least effective Sweeper Effectiveness Regenerative air vacuum sweeper - use 1-2 times/year for routine cleaning True vacuum sweeper very powerful for restoring highly clogged surfaces 21

22 Sediment collects in top ½ - 1 in. (13-25 mm) True vacuum sweeper cleans out clogged stone & restores surface infiltration refill with clean stone 22

23 Reinstated surface without damage or reduced service life 23

24 Exposed cap US Army Ft. Stewart, Georgia 24

25 Covered cap Exposed cap 25

26 Winter Maintenance Snow melts faster lower risk of ice Surface does not heave when frozen Use normal plows - dirty snow piles clog surface Deicing salts okay Sand will clog system use jointing material for traction 26

27 Managing dirty snow 10 yrs street winter sand accumulation Massachusetts 27

28 PICP Inspection Checklist from ICPI PICP manual Vacuum surface sediment Replenish aggregate in joints Inspect vegetation around PICP perimeter for cover & soil stability Repair all deformations exceeding 1/2 in. (13 mm) Repair pavers offset by more than 1/4 in. (6 mm) above/below adjacent units Replace broken units impairing surface structural integrity 1 to 2 times annually, adjust per loading As needed Annually, repair/replant as needed Annually, repair as needed Annually, repair as needed Annually Check drain outfalls for free flow of water & outflow from observation well Annually, after a major storm 28

29 Structural Design Conclusions All use empirical structural design methods PICP accounts for truck traffic loads and soil strengths, provides base/subbase thicknesses AASHTO 93 method reasonable for PICP Open- graded subbase/base more research needed in saturated base & soil condicons Need design catalog for PICP based on mechaniscc design TesCng needed using PA & PC bases for high ESAL facilices Maintenance Done with exiscng municipal vacuum equipment Based on use & periodic inspeccon, surface infiltracon tescng Surface traps most sediment, can be restored if fully clogged

30 Warrenville, IL