TRENCHING AND SHORING MANUAL - California …

1 CHANGE LETTER TRENCHING AND SHORING MANUAL Revision No. 01. OSC TRENCHING AND SHORING MANUAL . September 12, 2011. Attached are revisions to the TRENCHING and SHORING MANUAL . Please make the following changes in your MANUAL : SECTION REMOVE DATED SECTION INSERT DATED. MANUAL REVISION 01 06/11 MANUAL REVISION 01 08/11. COVER COVER. LIST OF PAGES ix, x 06/11 LIST OF PAGES ix, x 08/11. FIGURES FIGURES. CHAPTER 4 EARTH PRESSURE 06/11 CHAPTER 4 EARTH PRESSURE 08/11. THEORY AND THEORY AND. APPLICATION APPLICATION. CHAPTER 8 RAILROAD 06/11 CHAPTER 8 RAILROAD 08/11. Chapter 4, Earth Pressure Theory and Application , is revised to correct Equation 4-43. from: W [tan ( + )]+ C oLc [sin tan ( ) + cos ]+ C a La [tan ( ) co s( ) + sin ]. Pp =. [1 tan ( + )tan ( + )]cos ( + ). to: P =. [ ] [ ] [. W ta n ( + ) + C oL c sin ta n ( + )+ c os + C aL a tan ( + )cos ( ) + sin .. ]. p [ ]. 1 tan ( + )tan ( + ) c os ( + ). Chapter 8, Railroad , is revised to correct the application of the boussinesq loading to comply with the Railroad's Guidelines for Temporary SHORING .

2 The guidelines infer that the railroad live load should start at the top of the SHORING system and not at the top of the railroad roadbed. These changes are reflected as follows: o Pages revised: 4-27, 8-2, 8-17, 8-19 to 8-25, 8-27 to 8-31. o Figures revised: 8-1, 8-8, 8-9, 8-10, 8-12, and 8-14. o Tables revised: 8-3 thru 8-7. o Page added: 8-32. o Figure added: 8-15. ROBERT A. STOTT, Deputy Division Chief Offices of Structure Construction STATE OF California . DEPARTMENT OF TRANSPORTATION. TRENCHING . AND. SHORING . MANUAL . ISSUED BY. OFFICES OF STRUCTURE CONSTRUCTION. Copyright 2011 California Department of Transportation. All rights reserved. Revision 1. August 2011. TABLE OF CONTENTS. CHAPTER 1 LEGAL REQUIREMENTS. LEGAL REQUIREMENTS AND RESPONSIBILITIES .. 1-1. LABOR 1-3. Cal/OSHA .. 1-4. STATE 1-7. FEDERAL HIGHWAY ADMINISTRATION (FHWA) .. 1-7. RAILROAD RELATIONS AND 1-8. SHORING 1-9. SUMMARY .. 1-11. CHAPTER 2 Cal/OSHA.

3 Cal/OSHA .. 2-1. SOME IMPORTANT CalOSHA DEFINITIONS .. 2-3. SOME IMPORTANT Cal/OSHA REQUIREMENTS .. 2-5. General Requirements Section 2-5. Protective System 2-6. Soil Classification .. 2-8. Sloping or Benching Systems .. 2-10. Timber SHORING for Trenches .. 2-12. Aluminum Hydraulic SHORING for Trenches .. 2-14. Shield Systems .. 2-15. MANUFACTURED PRODUCTS .. 2-15. ALTERNATE DESIGN CONSIDERATIONS .. 2-17. INFORMATION ABOUT TEXT FORMATTING IN THE CONSTRUCTION SAFETY. ORDERS .. 2-17. CHAPTER 3 SOILS. 3-1. SOIL IDENTIFICATION, CLASSIFICATION, DESCRIPTION AND PRESENTATION.. 3-1. SOIL PROPERTIES and 3-3. STANDARD PENETRATION TEST (SPT).. 3-4. CONE PENETRATION TEST (CPT) .. 3-6. FIELD and LABORATORY 3-8. SHEAR STRENGTH .. 3-9. CONTRACTOR SOIL 3-10. SPECIAL GROUND CONDITIONS .. 3-11. CHAPTER 4 EARTH PRESSURE THEORY AND APPLICATION. i CT TRENCHING AND SHORING MANUAL . GENERAL .. 4-1. SHORING TYPES .. 4-1. Unrestrained SHORING 4-1.

4 Restrained SHORING Systems .. 4-1. 4-2. GRANULAR SOIL .. 4-4. At-Rest Lateral Earth Pressure Coefficient (K0).. 4-10. Active and/or Passive Earth Pressure .. 4-11. Rankine's Theory .. 4-11. Coulomb's Theory .. 4-14. COHESIVE SOIL .. 4-19. SHORING SYSTEMS AND SLOPING 4-24. Active Trial Wedge Method .. 4-25. Passive Trial Wedge Method .. 4-27. Culmann's Graphical Solution for Active Earth Pressure .. 4-28. Example 4-1 Culmann Graphical Method .. 4-33. Example 4-2 Trial Wedge Method .. 4-37. Example 4-3 (AREMA MANUAL page 8-5-12) .. 4-39. Example 4-4 (AREMA MANUAL page 8-5-12) .. 4-43. Example 4-5 (AREMA MANUAL page 8-5-13) .. 4-45. Example 4-6 (AREMA MANUAL page 8-5-13) .. 4-48. EFFECT OF WALL FRICTION .. 4-50. LOG SPIRAL PASSIVE EARTH 4-50. Composite Failure 4-52. Force Equilibrium Procedures .. 4-52. Moment Equilibrium 4-55. Noncomposite Log Spiral Failure 4-60. Force Equilibrium 4-60. Moment Equilibrium Method.

5 4-61. SURCHARGE LOADS .. 4-70. Minimum Construction Surcharge Load .. 4-70. Uniform Surcharge Loads .. 4-71. Boussinesq 4-72. Strip 4-72. Line Load .. 4-73. Point Load .. 4-74. Traffic Loads .. 4-76. Example 4-7 Sample Problem Surcharge Loads .. 4-79. Alternate Surcharge Loading (Traffic) .. 4-80. CHAPTER 5 STRUCTURAL DESIGN OF SHORING SYSTEMS. 5-1. ALLOWABLE WORKING STRESSES .. 5-1. ii TABLE OF CONTENTS. 5-1. 5-2. MECHANICS OF STRESS ANALYSIS .. 5-5. 5-7. 5-7. CHAPTER 6 UNRESTRAINED SHORING SYSTEMS. TYPES OF UNRESTRAINED SHORING SYSTEMS .. 6-1. LATERAL EARTH PRESSURES FOR UNRESTRAINED SHORING SYSTEMS .. 6-2. EFFECTIVE 6-9. DEFLECTION .. 6-11. SOIL PRESSURE DISTRIBUTION FOR LAYERED SOIL .. 6-13. Example 6-1 Cantilevered Soldier Pile Wall .. 6-14. Example 6-2 Cantilevered Soldier Pile Wall .. 6-17. Example 6-3 Deflection of a Cantilevered Soldier Pile Wall .. 6-23. CHAPTER 7 RESTRAINED SHORING SYSTEMS. LATERAL EARTH PRESSURES FOR RESTRAINED SHORING SYSTEMS.

6 7-1. COHESIONLESS SOILS .. 7-2. COHESIVE SOILS .. 7-5. Stiff to Hard .. 7-5. Soft to Medium Stiff .. 7-6. CALCULATION 7-8. Single Tieback/Brace System .. 7-8. Multiple Tieback/Brace System .. 7-10. 7-13. Example 7-1 Single Tieback Sheet Pile Wall .. 7-14. Example 7-2 Multiple Tieback Sheet Pile Wall .. 7-23. CHAPTER 8 RAILROAD. 8-1. SELECTED EXCERPTS FROM Guidelines for Temporary SHORING .. 8-2. 8-2. General Criteria .. 8-2. Types of Temporary SHORING .. 8-4. SHORING Box .. 8-4. Restrained Systems .. 8-4. Unrestrained 8-4. Cofferdam .. 8-4. General SHORING Requirements .. 8-5. iii CT TRENCHING AND SHORING MANUAL . Required .. 8-6. Field Survey .. 8-6. Geotechnical 8-6. 8-7. Drainage (AREMA ) .. 8-8. Structural Design Calculations .. 8-8. Computation of Applied Forces .. 8-8. Structural Integrity .. 8-9. EXAMPLE 8-1 (Railroad Example) .. 8-14. DEFLECTION CALCULATION .. 8-27. CHAPTER 9 CONSTRUCTION AND SPECIAL CONSIDERATIONS.

7 SPECIAL CONDITIONS .. 9-1. ANCHOR 9-2. Anchor Block in Cohesionless Soil .. 9-3. Anchor Block in Cohesionless Soil where D/H .. 9-9. Anchor Block in Cohesive Soil near the Ground Surface D H/2 .. 9-10. Anchor Blocks in Cohesive Soil where D H/2 .. 9-12. Example 9-1 Problem Anchor Blocks .. 9-13. HEAVE .. 9-16. Factor of Safety Against Heave .. 9-18. Example 9-2 Problem Heave Factor of Safety .. 9-20. PIPING .. 9-21. Hydraulic Forces on Cofferdams and Other Structures .. 9-21. SLOPE STABILITY .. 9-23. Rotational Slides .. 9-24. Fellenius Method .. 9-28. Example 9-3 Problem Fellenius Method .. 9-29. Bishop Method .. 9-31. Example 9-4 Problem Bishop Method .. 9-32. Translational Slide .. 9-33. Example 9-5 Problem Translational Slide .. 9-36. Stability Analysis of SHORING 9-37. The Last Word on 9-37. CONSTRUCTION CONSIDERATIONS .. 9-38. 9-38. Encroachment Permit Projects .. 9-41. Tieback Systems .. 9-44. Construction 9-44.

8 Tieback Anchor Systems .. 9-44. Tieback Anchor .. 9-47. Forces on the Vertical Members .. 9-50. Testing Tieback Anchors .. 9-51. iv TABLE OF CONTENTS. Proof Testing .. 9-53. Evaluation of Creep Movement .. 9-55. Wall Movement and 9-56. Performance Testing .. 9-56. Lock-Off Force .. 9-57. Corrosion Protection .. 9-58. Steps for Checking Tieback SHORING Submittal .. 9-59. Example 9-6 Tieback Testing .. 9-60. SUMMARY .. 9-62. Appendix A California OCCUPATIONAL SAFETY AND HEALTH. STANDARDS FOR EXCAVATIONS. Appendix B Memos Appendix C Surcharges Appendix D Sheet Piles Appendix E Examples Appendix F Brochures Appendix G Notes & FAQ's v CT TRENCHING AND SHORING MANUAL . vi LIST OF FIGURES. Figure 3-1. Cone Penetration Test (CPT) Boring .. 3-6. Figure 3-2. Typical CPT Plot .. 3-7. Figure 3-3. Mohr-Coulomb Criteria .. 3-9. Figure 4-1. Active and passive earth pressure coefficient as a function of wall displacement .. 4-2.

9 Figure 4-2. Comparison of Plane versus Curve Failure Surfaces .. 4-4. Figure 4-3. Lateral Earth Pressure Variation with Depth .. 4-5. Figure 4-4. Mohr Circle Representation of Earth Pressure for Cohesionless Backfill .. 4-7. Figure 4-5. Rankine's active 4-12. Figure 4-6. Rankine's passive wedge .. 4-13. Figure 4-7. Coulomb's active wedge .. 4-15. Figure 4-8. Coulomb's passive wedge .. 4-16. Figure 4-9. Mohr Circle Representation of Earth Pressure for Cohesive Backfill .. 4-19. Figure 4-10. Tension crack with hydrostatic water pressure .. 4-20. Figure 4-11. Cohesive Soil Active Passive Earth Pressure Distribution .. 4-21. Figure 4-12: Load Distribution for Cohesive 4-22. Figure 4-13. Sloping Ground .. 4-24. Figure 4-14. Active Trial Wedge .. 4-26. Figure 4-15. Passive Trial 4-27. Figure 4-16. Single Wedge and Force Polygon .. 4-28. Figure 4-17. Culmann Trial Wedges .. 4-30. Figure 4-18. Culmann Graphical Solution to Scale.

10 4-32. Figure 4-19. Retaining Wall with Irregular backfill by Culmann Method .. 4-33. Figure 4-20. Culmann Trial Wedge Method to Scale .. 4-34. Figure 4-21. Culmann Graphical Solution Using Force Polygon .. 4-36. Figure 4-22. Critical Active 4-37. Figure 4-23. Culmann AREMA page 8-5-12 .. 4-39. Figure 4-24. Culmann Trial Wedge .. 4-40. Figure 4-25. Culmann Graphical Solution Using Force Polygon .. 4-42. Figure 4-26. Critical Active Wedge Method .. 4-43. Figure 4-27. Retaining Wall with Irregular backfill .. 4-45. Figure 4-28. Culmann Trial Wedge .. 4-46. Figure 4-29. Culmann Force Polygon .. 4-47. Figure 4-30. Critical Active 4-48. Figure 4-31. Passive Active failure surface; straight line versus spiral surface of sliding.. 4-50. Figure 4-32. Geometry of the developing mobilized failure plane (Shamsabadi, et al,. 2005) . 4-51. Figure 4-33. Geometry of the failure surface and associated interslice 4-54. Figure 4-34.