PTI DC35.1-14: Recommendations for Prestressed Rock and Soil Anchors

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New! PTI DC35.1-14: Recommendations for Prestressed Rock and Soil Anchors

This publication represents the current state of the art in the design and construction of permanent and temporary prestressed rock and soil anchors using high-strength prestressing steel. The recommendations provide practical guidance for the design, installation, and testing of prestressed rock and soil anchors.

These recommendations supersede the 2004 edition and include major revisions in the requirements for: • Added "Extended Temporary Anchor" category • All permanent anchors = Class I protection • Added "Special Prestressing Materials" section • Minimum tendon bond length requirements • Improved guidance for anchorage protection • Improved guidance for coupler protection • New reference to ADSC grouted wedge testing • Improved guidance for repair of corrosion protection • Additional guidance for evaluating creep movement • Improved decision tree for anchors that fail • Guidance for epoxy-coated strand has been updated, remains in supplement section.

This document was prepared by the PTI Committee for Prestressed Rock and Soil Anchors (DC-35) with input and review by the Anchored Earth Retention Committee of the International Association of Foundation Drilling.

TABLE OF CONTENTS

1.0 — Scope

2.0 — Definitions

3.0 — Specifications, Responsibilities, and Submittals

3.1 — Specifications

3.1.1 — Prescriptive specifications

3.1.2 — Performance specifications

3.1.3 — Open specifications

3.2 — Responsibilities

3.3 — Submittals

3.3.1 — General

3.3.2 — Preconstruction submittals

3.3.3 — As-built records

4.0 — Materials

4.1 — General

4.2 — Prestressing steel

4.2.1 — Strand

4.2.2 — Bar

4.2.3 — Epoxy-coated strand

4.2.4 — Epoxy-coated bar

4.2.5 — Special prestressing materials

4.2.6 — Patching materials

4.3 — Anchorages

4.4 — Couplers

4.5 — Centralizers and spacers

4.6 — Corrosion-inhibiting compounds

4.6.1 — Grease

4.6.2 — Gel

4.6.3 — Wax

4.7 — Plastic tubing

4.7.1 — Bond breaker

4.7.2 — Sheath

4.7.3 — Tendon bond length encapsulations

4.8 — Heat-shrink sleeves and tapes

4.8.1 — Heat-shrink sleeves

4.8.2 — Heat-shrink tapes

4.8.3 — Petrolatum (wax) tapes

4.8.4 — Adhesive tapes

4.9 — Grout tubes

4.10 — Grout socks

4.11 — Cement grout

4.11.1 — Cement

4.11.2 — Water

4.11.3 — Aggregates

4.11.4 — Admixtures

4.11.5 — Supplemental cementitious materials

5.0 — Corrosion protection

5.1 — Design aspects

5.2 — Corrosion protection selection criteria

5.2.1 — Service life

5.2.2 — Aggressivity of anchor environment

5.2.2.1 — Soil resistivity

5.2.2.2 — pH

5.2.2.3 — Chemical properties of soil and groundwater

5.2.2.4 — Physical properties of soil and groundwater

5.2.2.5 — Potential stray current sources

5.3 — Corrosion protection requirements

5.4 — Corrosion protection details

5.4.1 — Anchorage protection

5.4.1.1 — Anchor heads

5.4.1.2 — Bearing plates and anchor head covers

5.4.1.3 — Trumpets

5.4.2 — Free stressing length protection

5.4.2.1 — Permanently unbonded free stressing length

5.4.2.2 — Fully or partially bonded free stressing length

5.4.3 — Free stressing length/bond length transition protection

5.4.4 — Tendon bond length protection

5.4.4.1 — Class I protection

5.4.4.2 — Class II protection

5.4.5 — Protection against stray currents

5.4.6 — Coupler protection

6.0 — Design

6.1 — Introduction

6.2 — Feasibility of anchors

6.3 — Design objectives

6.4 — General considerations

6.4.1 — Corrosion protection requirements

6.4.2 — Fully bonded, partially bonded, or unbonded anchors

6.4.3 — Restressable anchor systems

6.4.4 — Destressable and removable anchor systems

6.5 — Site evaluation

6.5.1 — Rock anchors

6.5.2 — Soil anchors

6.6 — Anchor design load and safety factors

6.7 — Bond length

6.7.1 — Rock anchors

6.7.2 — Soil anchors

6.8 — Free stressing length

6.9 — Anchor geometry

6.9.1 — Anchor spacing in bond length

6.9.2 — Drill hole diameter

6.9.3 — Overburden depth

6.9.4 — Anchor inclination

6.10 — Tendon components

6.10.1 — Anchorage

6.10.2 — Encapsulation

6.10.3 — Spacers and centralizers

6.11 — Grout mixture

6.12 — Grout socks

7.0 — Construction

7.1 — General

7.2 — Fabrication

7.3 — Storage and handling

7.4 — Drilling

7.4.1 — Open hole drilling

7.4.2 — Cased holes

7.4.3 — Hollow-stem augers

7.4.4 — Combination methods

7.4.5 — Hole alignment and tolerances

7.4.6 — Hole cleaning and overdrilling

7.5 — Water pressure testing, pregrouting, and redrilling rock anchor drill holes

7.6 — Tendon repairs

7.7 — Tendon insertion

7.8 — Grouting

7.8.1 — Grouting equipment and mixing

7.8.1.1 — Neat cement grouts

7.8.1.2 — Site-mixed sanded grouts

7.8.1.3 — Ready mixed sanded grouts

7.8.2 — QA/QC for mixed grout

7.8.2.1 — Preproduction lab tests

7.8.2.2 — Preproduction field tests

7.8.2.3 — Routine QA/QC during production

7.8.2.4 — Test methods for cement-based grouts

7.8.3 — Grouting operations

7.8.3.1 — Grouting uncased holes

7.8.3.2 — Grouting cased or hollow-stem auger holes

7.8.3.3 — Grouting encapsulated tendons

7.8.3.4 — Grouting very permeable ground

7.8.3.5 — Temperature considerations

7.8.4 — Post-grouting

7.9 — Installation of anchorage

8.0 — Stressing, load testing, and acceptance

8.1 — General

8.1.1 — Preparation prior to stressing

8.2 — Equipment

8.2.1 — Requirements for equipment

8.2.2 — Equipment setup

8.3 — Testing

8.3.1 — Preproduction tests

8.3.2 — Performance tests

8.3.3 — Proof tests

8.3.4 — Supplementary extended creep tests

8.4 — Lock-off procedure

8.5 — Initial liftoff reading

8.6 — Acceptance criteria

8.6.1 — Creep

8.6.2 — Movement

8.6.2.1 — Residual movement

8.6.2.2 — Minimum apparent free tendon length

8.6.2.3 — Maximum apparent free tendon length

8.6.3 — Initial liftoff reading

8.7 — Procedures in the event of failure during testing

8.8 — Finishing work for permanent anchors

8.8.1 — Cutting stressing tails

8.8.2 — Corrosion protection (Class I or II)

8.9 — Monitoring service behavior

9.0 — References

9.1 — Referenced standards

9.1.1 — ASTM International

9.1.2 — American Association of State Highway and Transportation Officials (AASHTO)

9.1.3 — American Public Health Association (APHA)

9.1.4 — American Water Works Association (AWWA)

9.1.5 — American Concrete Institute (ACI)

9.1.6 — American Petroleum Institute (API)

9.1.7 — Federal Test Method Standard (FTMS)

9.1.8 — Post-Tensioning Institute (PTI)

9.2 — Cited references

Supplement A — Supplementary requirements for epoxy-coated strand tendons

SA1.0 — Scope

SA3.0 — Specifications, Responsibilities, and Submittals

SA3.3.2 — Preconstruction submittals

SA4.0 — Materials

SA4.2.3 — Epoxy-coated strand

SA4.3 — Anchorages

SA6.0 — Design

SA6.6 — Anchor design load and safety factors

SA6.8 — Free stressing length

SA7.0 — Construction

SA7.2 — Fabrication

SA7.3 — Storage and handling

SA7.7 — Tendon insertion

SA7.9 — Installation of anchorage

SA8.0 — Stressing, Load Testing, And Acceptance

SA8.1 — General

SA8.1.1 — Preparation prior to stressing

SA8.2 — Equipment

SA8.2.1 — Requirements for equipment

SA8.3 — Testing

SA8.4 — Lock-off procedure

SA8.6 — Acceptance criteria

SA8.6.1 — Creep

SA8.6.1.1 — Creep correction values

SA8.6.1.2 — Creep test options

SA8.6.1.4 — Acceptance criteria

SA8.6.2 — Movement

SA8.6.2.2 — Minimum apparent free tendon length

SA8.7 — Procedures in the event of strand slippage through wedges

SA9.0 — References

SA9.2 — Cited references

Supplement B — Requirements for polyester resin rock anchors

SB1.0 — Scope

SB1.1 — Definitions

SB1.2 — Specification, responsibilities, and submittals

SB1.3 — Materials

SB1.4 — Corrosion protection

SB1.5 — Design

SB1.6 — Installation

SB1.7 — Testing

SB1.7.1 — Performance testing

SB1.7.2 — Proof testing

Publisher: PTI/November 2014/109 pages/8.5 x 11 in. (Soft cover)/ISBN NO. 9780870319471