Rehabilitation of Existing River Piers for

Transcription

1 Creating Value Delivering Solutions Rehabilitation of Existing River Piers for Dick Henderson Bridge, West Virginia i i Joe Carte, P.E. W.V. Department of Transportation Scott Zang, P.E. Michael Baker Jr., Inc.

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3 Project Location location West Virginia Charleston 3

4 Project Location I-64 Bridges Dick Henderson Bridge Charleston 4

5 Nitro Project Location St. Albans 5

6 Existing Bridge Nitro Built 1934, Rehabbed Ton Weight Limit St. Albans 6

7 Existing Bridge 20 ADT (2007) Functionally Obsolete Sufficiency rating 42.5 out of 100 7

8 Proposed bridge 8

9 Why reuse the piers? 9

10 Nitro Residential Residential School Fields Marina/ docks Car Dealer St. Albans 10

11 Schedule Reusing existing piers shortens the time the bridge is out of service BRIDGE CLOSED 11

12 Permitting Permitting for new piers not required 12

13 Span Length and Grade Required grade to clear extended opening Existing Opening = 450 x60 Possible Required Opening for New Bridge = 600 x 70 13

14 Condition of Existing Main Piers Sound except at very top In Depth Inspection 14

15 Condition of Existing Main Piers 15

16 Subsurface Conditions 600 Very thin soil (0-3 ) Clay 550 Silty Sand Soft Claystone 500 Sandy Shale 16

17 Soft Claystone Sandy Shale 17

18 Evaluation of Existing Spread Footing B (ft) q R Strength Limit State φ = (KSF) q R Extreme Limit State φ = (KSF)

19 Evaluation of Existing Spread Footing F x Extreme II Barge Impact F x = 1377 kips 40.4 V V = 6758 kips e = 82ft 8.2 ft. B = 2.1 ft σ = 74.4 ksf ksf >596ksf

20 Micropile Concept Construction Sequence 1. Install cofferdam 20

21 Micropile Concept Construction Sequence 2. Install micropiles 21

22 Micropile Concept Construction Sequence 3. Place tremie seal 22

23 Micropile Concept Construction Sequence 4. Dewater cofferdam 23

24 Micropile Concept Construction Sequence 5. Cast new footing 24

25 Micropile Concept Construction Sequence 6. Cast stem encasement 25

26 Micropile Concept 12 clear to new footing 10 ¼ Hole 9 5/8 OD x 0.5 wall N80 pipe 5000 psi grout 2 x #18 Gr Casing embedment 28 Bond zone q r = 526 kips 26

27 3 Months less closure time Improve Existing Pier Time Savings? None overall Vs. Reduced superstructure cost Cost Savings? None for pier Demolish and Build New Pier 27

28 Construction 28

29 Contractor s Proposed Pile Construction ti Method 1. Place drilling deck with 14 guide pp pipes 29

30 Contractor s Proposed Pile Construction ti Method 2. Install temporary 11 pipe pp into competent rock or top of existing footing 30

31 Contractor s Proposed Pile Construction ti Method 3. Drill hole to final tip elevation 31

32 Contractor s Proposed Pile Construction ti Method 4. Lower permanent N80 casing and center reinforcing bar to bottom of hole NOTE: permanent casing is coupled to reinforcing bar with custom bracket that suspends it at the proper height ht in the hole 32

33 Contractor s Proposed Pile Construction ti Method 5. Lower grout standpipe over top of permanent casing. NOTE: Grout standpipe seals to top of permanent casing with a rubber compression seal and is held down by drill rig 33

34 Contractor s Proposed Pile Construction ti Method 6. Insert grout tremie tube to bottom of pile 7. Place grout till return is observed in outside pipe 34

35 Contractor s Proposed Pile Construction ti Method 8. Remove tremie tube 9. Install pressure cap and pressurize till grout returns or 100 psi 35

36 Contractor s Proposed Pile Construction ti Method 10. Remove standpipe 11. Remove e temporary casing pipe 36

37 Pre-Production Load Tests Clay Silty Sand Soft Claystone Sandy Shale 37

38 Test Pile Installation 38

39 Test Setup 39

40 St. Albans - Results Dis splacem ment (in n) Load (kips) Top of Pile Elastic Compression Approx. Max. bond stress mobilized = 62.1 psi 40

41 Drilling Piles 41

42 Installing Reinforcing and Casing 42

43 Tremie Grouting Grout Return 43

44 Grout Return Grout Pressurization 44

45 Encapsulation Dowels 45

46 Excess Grout Cleanout by Divers 46

47 Dewatering Cofferdam 47

48 Dewatered Cofferdam 48

49 Dowel Holes and Piles 49

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52 Creating Value Delivering Solutions Questions? Joe Carte, P.E. W.V. Department of Transportation Scott Zang, P.E. Michael Baker Jr., Inc.