1 Segmental Retaining Walls Best Practices Guide for the Specification, Design, Construction, and Inspection of SRW Systems Table of Contents | Segmental Retaining Walls Best Practices Guide About NCMA..3. Acknowledgments ..3. Preface ..4. Chapter 1 Preconstruction Considerations ..5. Design Roles and Responsibilities..6. Site Civil Engineer Responsibilities ..6. SRW Design Engineer Responsibilities ..6. Planning Considerations..7. Project Objectives ..7. Site Planning and Layout ..8. Geotechnical Report ..8. SRW Construction Drawing Submittals..8. Project Bidding..9. Preconstruction Meetings ..9. General Design Considerations ..9. Wall Embedment Depth .. 11. Chapter 2 SRW Units and Geosynthetic Materials .. 13. SRW Units.. 13. Minimum Property Requirements for SRW Units.
2 13. Freeze/Thaw Durability Requirements .. 14. Sulfate Resistance .. 16. Geosynthetic Reinforcement .. 16. Geotextile Material (Filter Fabric).. 17. Chapter 3 Soils and Compaction .. 19. On-Site Soils.. 20. Foundation Soils .. 20. Reinforced Soils .. 20. Retained Soils .. 21. Gravel Fill .. 21. Compaction Requirements at the Wall Face .. 22.. 22. Inspection and Testing Recommendations .. 22. Chapter 4 Water Management; General Design Considerations 23. Water Management.. 24. Surface Water .. 24. Below Grade Water .. 25. Chapter 5 Construction Considerations.. 31. Contractor Experience.. 31. Leveling Pad.. 31. Drain Pipe.. 31. SRW Unit Placement.. 32. Compaction Requirements.. 32. Water Management during Construction .. 32. Capping and Finish Grading.
3 32. Wall Step-Ups in Base Course .. 32. Stair Considerations .. 33. Construction Tolerances.. 33. Construction Safety .. 33. Segmental Retaining Walls Best Practices Guide Table of Contents | 1. Table of Contents | Segmental Retaining Walls Best Practices Guide Chapter 6 Geosynthetic Reinforcement Installation.. 35. General .. 36. Proper Orientation of Geogrid and Placement .. 36. Chapter 7 Inspection and Quality Assurance .. 37. Overview.. 37. Soil Inspection and Testing .. 37. SRW Units.. 37. Geosynthetic Reinforcement .. 37. Chapter 8 Tall Walls .. 39. Tall Walls .. 40.. 40. Compaction Requirements.. 40. Gravel Fill at the Face .. 40. Quality Control, Quality Assurance .. 40. SRW Unit Height Tolerances .. 41. Cracking .. 41. Chapter 9 Global Stability.
4 43. General .. 44. Wall Embedment with Toe Slope.. 44. When to Analyze Global Stability.. 44. Increase Global Stability Options.. 44. Chapter 10 Terraced Walls .. 45. Tiered or Terraced Walls .. 46. Chapter 11 Water Applications .. 47. Water Applications.. 48. Chapter 12 Seismic Considerations .. 49. Seismic Considerations.. 50. Chapter 13 Above Wall Considerations .. 51. Above the Wall Considerations .. 52. Minimum Geogrid Lengths at the Top of the Wall .. 52. Fences and Railings .. 52.. 52. Slopes Above the Wall .. 52. Landscaping .. 52. Chapter 14 Corners and Radii.. 53. General .. 54. Chapter 15 Checklists .. 57. Preconstruction Checklist .. 57. Design Checklist .. 57. Construction and Inspection Checklist .. 57. Post Construction Checklist.
5 59. Chapter 16 Notations .. 61. Chapter 17 References .. 63. 2 | Table of Contents National Concrete Masonry Association | Segmental Retaining Walls Best Practices Guide for the Speci cation, Design, Construction, and Inspection of SRW Systems About NCMA. The National Concrete Masonry NCMA promotes the use of Segmental information is accurate and conforms Association (NCMA) is an international Retaining wall products through the to current engineering Practices . NCMA. trade association representing development and dissemination of assumes no responsibility for errors or producers and suppliers in the concrete technical information. This Guide was omissions resulting from the use of masonry and hardscape industry. prepared by NCMA and is intended this Guide .
6 The Association is dedicated to the for use by those involved in the advancement of manufactured concrete All illustrations and other graphic products through research, promotion, inspection, and maintenance of SRW representation published in this education, and the development of systems. The material presented manual are property of NCMA unless manufacturing guides, design codes herein has been reviewed by otherwise noted. and resources, testing standards, and numerous individuals from a variety construction Practices . of backgrounds to ensure the enclosed Acknowledgments The efforts undertaken by Allan Block Additional reviewers and contributors Allan Block Corporation; Karen Nelson, Corporation in the initial drafting of to this Guide include: Don Armstrong, Versa-Lok Corporation; David Pitre, this publication are greatly appreciated Anchor Wall Systems/Oldcastle; Tim Pavestone Systems; Robert Race, Race as is the support and commitment of Bott, Allan Block Corporation; Glenn Engineering; Scott Vollmer, Oldcastle.
7 NCMA's SRW Technical Subcommittee. Herold, Oaks Concrete; Rich Lovdal, 2016 National Concrete Masonry Association | 13750 Sunrise Valley Drive | Herndon, VA 20171 | NCMA Publication Number: TR308. Edition: 1. Printing: 1 - Last Revised March 18, 2016. Segmental Retaining Walls Best Practices Guide | 3. Preface This Guide , Segmental Retaining Walls with the appropriate knowledge and . the wall owner. experience should be contracted by the project site civil engineer. It is of SRW Systems, is published and Segmental Retaining wall projects recommended that the wall contractor maintained by the National Concrete cover the spectrum of applications; not be responsible for securing the Masonry Association (NCMA). Since from simple, do-it-yourself projects to design services.
8 Segmental Retaining wall systems were highly complex endeavors involving multiple, interdependent design and When properly executed, SRW. has been a continuous evolution and construction considerations. The structures offer long-lasting solutions to advancement in the understanding scope of this Guide applies to those a wide array of applications. Successful of the technology and performance projects where an SRW design engineer projects, require: of these systems related to material is needed to assess site conditions, The use of quality materials properties, design recommendations, interpret the recommendations of this suitable for the anticipated and construction Practices . This Guide Guide , and apply engineering judgment exposure conditions.
9 As necessary for a successful project. The context of the discussion and A thorough understanding of knowledge collected over several recommendations presented in this SRW design methodology and the . Guide is limited solely to reinforced potential impacts site variables (soil proven solutions using Segmental SRW applications. Refer to NCMA's conditions, site geometry, water Retaining Walls (SRWs). The information Design Manual for Segmental Retaining management, loading sources and and recommendations presented in Walls (Ref. 1), TEK 18-11B, scenarios, etc.) can have on the this Guide are intended to augment the Guide for Segmental Retaining Walls performance of SRW systems;. design Practices and recommendations contained within NCMA's Design Manual (Ref.)
10 14), and related industry resources Clear communication between for Segmental Retaining Walls (Ref. 1), for additional guidance, information all parties (owner, designer, but are equally applicable regardless of and recommendations for both contractor, etc.) before, during, the design methodology selected. conventional (gravity) and reinforced and after construction; including SRW applications. The scope of this a thorough understanding of The creation of this resource was driven Guide does not apply to DIY residential performance objectives, roles and by the establishment of NCMA's Zero applications and projects of similar, responsibilities; and Failures Initiative; an industry-wide smaller scope where an engineer is Adherence to construction program to educate owners, designers, not involved.