Support of Transmission Line Structures Using HELICAL ANCHORS and PILES

Transcription

1 Support of Transmission Line Structures Using HELICAL ANCHORS and PILES

2 MITCHELL SCREW PILE & MOORING Maplin Sands Lighthouse st Recorded use was by Alexander Mitchell ( ) in 1836 for Moorings and was then applied by Mitchell to Maplin Sands Lighthouse in England in 1838 U.K. Patent No (renewed 1847) U.S. Patent No April 1, 1845

3 Advantages Screw Anchors/Piles Quick, Easy Turnkey Installation Immediate Loading Small Installation Equipment Pre-Engineered System Easily Field Modified Torque to Capacity Correlation Install in Any Weather Solution for: Restricted Access Sites High Water Table Weak Surface Soils Environmentally Friendly No Vibration No spoils to Remove No Concrete

4 Helical Piles Why Use Helical Piles? 1. Economically handle the loads Uplift Compression Shear and overturning moment due to wind loads 2. Resists Up-Heave due to: Ground Freeze Expansive Soils

5 3. Environmental Benefits: No excavation Eco system simplified permitting Removable, reuse or recycle Quiet installation Soil compaction without changing mean elevation 4. Fast, simple, low cost installation Standard excavation equipment Inexpensive Tooling High Production rates 100+ piles/day/crew Load the piles immediately Minimal training needed (a specialty contractor is not required)

6 Square Shaft Helical Products CHANCE SCREW ANCHORS SS5,SS150, SS175, SS200 & SS225

7 SQUARE SHAFT 356 mm 36 3 m 305 mm 254 mm 203 mm CHANCE Helical Anchors & Piles Tension/Compression Lead Section Helical Extension Extension

8 SQUARE SHAFT Torsion & Tension Ratings SS125 4,000 ft-lb 50 kip SS5 5,500 ft-lb 70 kip SS150 7,000 ft-lb 70 kip SS175 10,500 ft-lb 100 kip SS200 16,000 ft-lb 150 kip SS225 23,000 ft-lb 200 kip kgf kgf kgf kgf kgf kgf CHANCE Helical Anchors & Piles Tension/Compression Shaft Grade 70,000 psi (483 mpa) & 90,000 psi (621 mpa) minimum Helix Grade 50,000 psi (345 mpa) & 80,000 psi (552 mpa)

9 Square Shaft Series Product Ratings Product Series Torque Rating ft-lb (N-m) Ultimate Tension Strength* lb (metric ton) Tension Capacity in Soil** lb (metric ton) SS (7500) (32) (25) SS (9500) (32) (32) SS (14240) SS (21700) SS (31200) (45) (45) # (68) (68) # (91) (91) # * Based on Mechanical Strength of Coupling. ** Based on Shaft Torque Rating Tension/Compression = Shaft Torque Rating x K t Default K t for the SS Series = 10 ft -1 # Limited by Mechanical Strength of Coupling

10 Pipe Shaft Helical Products CHANCE SCREW PILES RS2875, RS3500, RS4500,RS8625, RS10750

11 ROUND SHAFT HELICAL PILES Torsion and Capacity Ratings CHANCE Helical Anchors & Piles Tension/Compression RS ,500 ft-lb 60 kip RS ,000 ft-lb 90 kip RS ,000 ft-lb 120 kip RS ,000 ft-lb 140 kip Shaft Grade 50,000 psi (345 mpa) minimum Helix Grade 50,000 psi (345 mpa) & 80,000 psi (552 mpa)

12 SS to PIPE SHAFT COMBO PILE 1-1/2 Square Shaft to RS /4 Square Shaft to RS Square Shaft to RS /4 Square Shaft to RS

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15 HELICAL PILES WITH GROUTED SHAFTS HELICAL PULLDOWN Micropile Characteristics ,000 ft lbs. Installation Torque Design Tension Loads up to 100 kip (445 kn), Design Comp. Loads up to 200 kip (890 kn) Helix Dia: 6 (152 mm) 8 (203 mm) 10 (254 mm) 12 (305 mm) 14 (356 mm), 16 (406 mm) Prevents Buckling Increases Capacity Corrosion Resistance Uses Type SS (Square Shaft) and RS (Pipe Shaft) Material

16 Grouted Helical Piles These Techniques Result in Grouted Helical Anchors

17 Grout Column in Sand Usually Cannot extract by direct pull Must look at grout formation in sands by excavation

18 CONSIDERATIONS Requires Grout and Displacement Plates Estimate 10% TO 15% additional cost based on 30 ft. pile Takes time and labor to mix grout Potential for Draw-Down in Compressible Soils. Potential for Negative Skin Friction in Expansive and Frozen Soils. Hydrostatic Pressure Required to Keep Grout Column Open. Usually Limited to Soils with SPT Blow Counts < 20 blows/ft

19 LARGE DIAMETER PIPE PILES 219 mm 168 mm RS ,000 ft-lb 300 kip RS ,000 ft-lb 200 kip kgf kgf

20 LARGE DIAMETER PIPE COUPLING

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23 ALLOWABLE CAPACITY Allowable Capacity Evaluated for Compression, Tension, Transverse Shear or a Combination of All Three Four Structural Elements Bracket Capacity Shaft Capacity Helix Capacity Soil Capacity

24 Screw Anchor/Pile Capacity in Soil Information Needed Clay & Silt (Fine Grain Soil) Cohesion (shear strength) Unit weight N value, or blow count from Standard Penetration Test (SPT) Sand & Gravel (Granular Soils) Phi (φ) angle (angle of internal friction) Unit weight N value from Standard Penetration Test (SPT) Water Table Elevation

25 Soils Suitable for Screw Anchor/Piles Granular Soils - Sand & Gravel

26 Soils Suitable for Screw Anchor/Piles Cohesive Soil Clay and Silt

27 Soils Not Suitable for Screw Anchor/Piles Not For Helical Anchors/Piles! Solid Rock

28 Plate Bearing Capacity Model Minimum Depth 5D UC f Total Capacity Equal to Sum of Individual Helix Bearing Capacities D Model valid for both tension and compression D 1 Helix Spacing Helix Spacing 3D 1 Min. Depth 5D (Default) Capacity (UC f ) Due to Friction Along Shaft = Zero.

29 Individual Helix Bearing Method Q ULT = ΣQ H where: Q ULT = Total Multi-Helix Anchor Capacity Q H = Individual Helix Capacity Q H = A H (CN C + qn q ) Q S - where: A H = Projected Helix Area Q S = Upper Limit Determined by Helix Strength

30 HeliCAP v2.0 Helical Capacity Software Provides the Theoretical Bearing Capacity - Based on Soil Strength For design purposes, Hubbell/Chance distributes a software package to engineers. This program, HeliCAP -v2.0, uses soil parameters chosen by the engineer to compute and output theoretical anchor capacities for design. Available from Chance Civil Construction Web Site

31 HeliCAP v2.0 Software HeliCAP v2.0 Workpage US Units

32 LOAD TRANSFER Friction & Bearing Two Mechanisms Side Friction, P s (skin friction) Toe-bearing Resistance, P t (point-bearing resistance,end bearing resistance, tip bearing resistance)

33 FRICTION CAPACITY EQUATION Q f = Σ[πDf s L f ] where: D = Diameter of Grouted Pile Column f s = Sum of Friction and Adhesion between Soil and Pile (force/area) L f = Incremental Pile Length over which πd and f s are Taken as Constant

34 HeliCAP Friction Module No Need to Do Hand Calcs Let HeliCap Do it for You!!

35 Skin Friction from Various Sites Project Location Soil Description Average Friction Resistance (ksf) AT/FP Site Improvements Norfolk Naval Shipyard, Portsmouth, VA Soft/loose to medium silty clays and sands under medium-dense fill 1.8 McDuffie Island Coal Terminal Mobile, AL Soft clay over sand of increaseing blow count with depth 1.2 R.W. Harris Site Clearwater, FL Loose, wet sand w/ limestone lenses over stiff clay Eaton Dam site Leadwood, MO Sand tailings - φ = 33, γ = 105 pcf, c= Phillies Baseball Stadium Philadelphia, PA Loose to medium dense sand fill over soft to medium stiff clay 0.64 S & ME Office Building Mt. Pleasant, SC Soft clay and/or loose fine grained sands w/ fines Cooper Marl ft below surface 0.7 Duhon Machinery Yard Kenner, LA Soft clays and silts with occasional sand layers 0.5 Harrah s Casino St. Louis, MO Stiff to soft clay fill over loose to medium-dense sand 1.2

36 Lateral Analysis Using Finite Difference Methods (LPILE) Limiting Criteria: 1. Pile-Head Deflection 2. Bending Moment 3. Shear

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38 Torque to Capacity Correlation The Torque Required to Install a Helical Pile or Anchor is Empirically Related to Its Ultimate Capacity. Q ult = K t T Where: Qult = Ultimate Capacity [lb (kn)] K t = Empirical Torque Factor [ft-1 (m-1)] Default Value = 10 (33) for Type SS Default Value = 8 (26) for 2-7/8 Pipe Shaft Default Value = 7 (23) for 3-1/2 Pipe Shaft Default Value = 6-7 (20-23) for 4-1/2 Pipe Shaft Default Value = 4-5 (20-23) for 6 & 8 Pipe Shaft T = Installation Torque, [ft-lb (kn-m)]

39 Digital Torque Indicator New Product Measures Torque in ft-lb. Continuous Duty Torque Indicator, or Can be Used to Calibrate Pressure Gauge on Installation Equipment Wireless Unit available 1Q 2014

40 Helical Pile Installation

41 INSTALLATION LOG TORQUE VS. DEPTH SSI75 w/ 8, 10, 12 & 14 in HELICES, LENGTH 31 FT VERTICAL INSTALLATION CLAY SOIL Torque at Termination: Best if Steady or Increasing TORQUE (ft-lb) DEPTH (ft)

42 Example of Installation Torque Depth (ft) Torque Data- Depth = 15ft a-AG, Helix Diameter = 8" Torque (ft-lb)

43 Test Date: Oct 2005 Centralia, MO Load vs. Deflection Load (kip) Type SS /4 Square Shaft Pile Length = Deflection (in) TP-7 PL/AE PL/AE + 0.1D Average Torque = 5733 ft-lb Kt = 12.2

44 Torque Correlation AC358 Section Torque Correlation Verification Conforming Systems 1.5 & 1.75 Square Shaft Kt = /8 OD Pipe Shaft Kt = 9 3 OD Pipe Shaft Kt = 8 3-1/2 OD Pipe Shaft Kt = 7 Verification Requires 14 Full-Scale Load Tests in Soil Non-Conforming Systems Verification Requires 28 Full-Scale Load Tests in Soil

45 Corrosive Environments Soil Type Granular soils sand & gravel Fine grained clay and silts Organics Contaminants Disturbed versus undisturbed Moisture Content Corrosion potential increases with an increase in moisture content Saturated soils with little or no oxygen have reduced corrosion potential ph Neutral soils with ph~7 have lower corrosion potential Resistivity Used to determine corrosion potential Low resistivity means higher corrosion potential

46 Corrosion Protection Typical Life Expectancy for Galvanized Steel Screw Anchors/Piles in Soil Exceeds 100 Years Based on soils that are considered mildly corrosive 1/8 inch (3.2 mm) loss of material on shaft Sacrificial loss of steel Corrosion allowance Hot dipped galvanizing or other coatings (passive control) Zinc Nylon coated bolts Bituminous or asphaltic coatings Sacrificial anodes (active control) Magnesium or zinc bags

47 Applications Transmission and Substation

48 WIND PRESSURE ON POLE Loads Steel Pole Line Single Mast Mono-Pole Line Deflected Shape

49 Wind Pressure (P) LOAD at GROUNDLINE Moment Large Shear Moderate Compression - Light Moment (M) Force (F)

50 2 POLE STRUCTURE Moment Moderate Shear Moderate Compression - Light Deflected Shape 2 Pole Structure

51 H FRAME STRUCTURE Moment Low Shear Moderate Compression Light Tension - Light Deflected Shape H-Frame Structure

52 SELF SUPPORT LATTICE STRUCTURE Moment Low Shear High Compression High Tension - High

53 SELF SUPPORT LATTICE STRUCTURE Moment Low Shear Light Compression High Guy - Moderate

54 Saskpower 230 kv Transmission Line Structure: Location: Soil: clay. Frost Depth: Guyed Steel H-Frame Construction Saskatoon to Regina, Saskatchewan Medium dense sand and gravel. Some isolated pockets of stiff 7 feet

55 Saskpower 230 kv Transmission Line Type 1 Anchorage 221 kn (50 kip) Acceptance Criteria: No anchor creep greater than 12 mm (1/2 inch) allowed after 60 seconds at this pull-out load. Type 2 Anchorage 275 kn (62 kip) Acceptance Criteria: No anchor creep greater than 12 mm (1/2 inch) allowed after 60 seconds at this pull-out load. Type 3 Anchorage 400 kn (90 kip) Acceptance Criteria: No anchor creep greater than 12 mm (1/2 inch) allowed after 60 seconds at this pull-out load.

56 Saskpower 230 kv Transmission Line Type 1 (Option 2) 221 kn (50 kip) SS175 w/ 8, 10 & 12 Installation Torque 6,000 ft-lb

57 Saskpower 230 kv Transmission Line Type kn (62 kip) SS175 w/ 8, 10 & 12 Installation Torque 6,700 ft-lb Option w/14 helix extension

58 Saskpower 230 kv Transmission Line Type kn (90 kip) SS200 w/ 8, 10, 12 & 14 Installation Torque 10,000 ft-lb Option w/14 helix extension

59 Saskpower 230 kv Transmission Line

60 RIO MADEIRA PROJECT 600kV dc Line June 2010 Update

61 D Porto Velho Araraquara 1 600kV Line CC 2375km - Consorcio Madeira G Porto Velho Araraquara 2 600kV Line CC 2375km Consorcio Integração Norte B Cuiaba Rio Verde 500kV Line HB 602km - Cymi

62 Rio Madeira 600 kv Transmission Line

63 Rio Madeira 600 kv Transmission Line CHANCE Type SS200 Helical Anchor

64 Rio Madeira 600 kv Transmission Line

65 Ejemplo para uso en anclaje de Tirante Linha Porto Velho-Araraquara Tipo: Estaca maciza Modelo SS200 Carga ruptura: 68t Torque Instalacion: 14,000 ft-lbs

66 Tension Test to Ultimate Capacity

67 Tension Test Type SS200 Anchor

68 Guy Anchor Test Rio Madeira - Brazil 500 kv Guyed Structure Max Test Load: 130 kip Type SS200 Anchor

69 Engevix - Brazil Transmissora Sul Litoranea De Energia, S.A. LT 525 kv Marmeleiro Povo Novo

70 Helical Pile Supported Mast Base Type SS175/RS3500 Helical Pile

71 Helical Guy Anchor Supported Tower Type SS200 Anchors

72 Helical Pile Supported Tower Base 4-Legged Self-Support Type SS175/RS3500 Helical Piles

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74 Compression Test Type SS175/RS3500 Helical Pile

75 San Pedero Sula - Honduras Caracol Knit kv Electrical Feed for Biomass and Textile Plants

76 Three Self-Support Towers Helical Piles: CHANCE Type SS175/RS Combo Piles Training Installation Crew at first Tower Site

77 Pouring Pile Caps

78 Loads: Approx. 170 kip per Leg Four Helical Piles per Leg Production Rate: One tower/per day (16 piles per day)

79 Xcel Energy Stinson-Bayfront Helical Pile Foundations Line 3315, 32.1 mile rebuild 115 kv H-Frame

80 Structure Types Running Angle Deadend

81 Xcel Energy Stinson - Bayfront 115 kv Full Scale Load Tests Hager City, WS

82 Load Cases

83 Forces in Helical Piers (KIPS) Axial Force is positive for uplift and negative for compression Deadend Deadend Reactions Case 1 Case 2 Pier Vertical Shear Y Shear Z Vertical Shear Y Shear Z

84 Running Angle Reactions Forces in Helical Piers (KIPS) Axial Force is positive uplift and negative compression Running Angle Case 3 Case 4 Pier Vertical Shear Y Shear Z Vertical Shear Y Shear Z

85 Deadend Load Case 1 100%

86 Deadend Case Case 100%

87 Running Angle Case 100% Case 100%

88 Test Deflections Type Pole Top Flange Plate Pile (up) Pile (down) Pile Lateral Deadend Running Angle

89 Xcel Energy Stinson - Bayfront 115 kv

90 Steel Tri-pod Grillage

91 Hydro One Networks Tower Foundation Replacement with Helical Piles 500 kv Guyed V-Shaped Structures

92 Hydro-One Networks 500 kv Towers Note Jig that Allows the Track-hoe Operator Visually Check the Installation Angle

93 Hydro-One Networks 500 kv Towers Piles Installed and Awaiting Cut-off

94 Hydro-One Networks 500 kv Towers Tower Structure Being Lifted off Old Grillage Foundation

95 Hydro-One Networks 500 kv Towers Tower Grillage Complete and Ready for Backfill

96 Self-Supported Structures

97 Four Leg Self Support Tower

98 Three Screw Piles per Leg

99 Winter Construction

100 Grillage Fabricated in the Field

101 Monopole in Remote Site

102 Screw Pile Supported Steel Grillage

103 Guyed Telecom Tower 330 Guyed Tower At Morganza, LA Fan/Spreader Plate Assembly 7 Guywires to 4 SS5 Series Anchors Required Total Ultimate Capacity = kips

104 Installation Machine Swamp Buggy South Bend, LA Installation of 6 Guy Anchor Cluster Resultant Design Load = 95.0 kips

105 Multi-Screw Pile Concrete Pile Cap South Bend, LA Guyed Tower 12 RS Series Piles for Tower Mast Required Ultimate Capacity per Pile = 70.0 kips

106 Multi-Screw Anchor Guy Point in Concrete Guyed Tower at Abita Springs, LA 4 SS175 Series Anchors at the Inner Guywire Cluster Resultant Load = kips 4 SS175 Series Anchors at the Outer Guywire Cluster Resultant Load = 94.0 kips

107 Multi-Screw Piles with Concrete Cap SST at Bayou Blue (Houma), LA 12 Stepped Helical Pulldown Micropile per tower leg Ultimate Capacity per pile = 95.0 kips Load Tested to over kips in tension Installed Depths = 70-0

108 Installation Equipment SST at Bayou Blue (Houma), LA 12 Stepped Helical Pulldown Micropile per tower leg Pile Installation using John Deere

109 Augmentation of Existing Foundation

110 Instant Screw Pile Foundations Roadway Lighting, Parking Lots, Site Lighting Maximum installing torque 6 5/8 O.D. 15,000 ft-lb. 8 5/8 O.D. 20,000 ft-lb. 10 3/4 O.D. 20,000 ft-lb.

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