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TRENCHING and SHORING MANUAL – Revision No 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 (α + φ ) + C o Lc sin α tan (α − φ ) + cos α ][ + C aL a tan (α − φ )co s (− ω ) + sin ω ] P = p [1 − tan (δ + ω )tan (α + φ )]cos (δ + ω ) to: W [ta n ()α + φ ] + C o L c[ sin α ta n ()α + φ + c os α] + Ca L a[tan ()()α + φ co s −ω + sinω ] P = . p [1 − tan (δ + ω )tan (α + φ )] c os (δ + ω ) Chapter 8, “Railroad”, is revised to correct the application of the boussinesq loading to comply with the Railroad's Guidelines for Temporary Shoring. 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 1.0 LEGAL REQUIREMENTS AND RESPONSIBILITIES ................................................ 1-1 1.1 LABOR CODE .................................................................................................................. 1-3 1.2 Cal/OSHA ......................................................................................................................... 1-4 1.3 STATE STATUTES .......................................................................................................... 1-7 1.4 FEDERAL HIGHWAY ADMINISTRATION (FHWA) ................................................. 1-7 1.5 RAILROAD RELATIONS AND REQUIREMENTS ......................................................1-8 1.6 SHORING PLANS ............................................................................................................ 1-9 1.7 SUMMARY .................................................................................................................... 1-11 CHAPTER 2 Cal/OSHA 2.0 Cal/OSHA ......................................................................................................................... 2-1 2.1 SOME IMPORTANT CalOSHA DEFINITIONS ............................................................ 2-3 2.2 SOME IMPORTANT Cal/OSHA REQUIREMENTS ..................................................... 2-5 2.2.1 General Requirements Section 1541 .................................................................... 2-5 2.2.2 Protective System Selection .................................................................................2-6 2.2.3 Soil Classification ................................................................................................ 2-8 2.2.4 Sloping or Benching Systems ............................................................................ 2-10 2.2.5 Timber Shoring for Trenches ............................................................................. 2-12 2.2.6 Aluminum Hydraulic Shoring for Trenches ...................................................... 2-14 2.2.7 Shield Systems ................................................................................................... 2-15 2.3 MANUFACTURED PRODUCTS .................................................................................. 2-15 2.4 ALTERNATE DESIGN CONSIDERATIONS .............................................................. 2-17 2.5 INFORMATION ABOUT TEXT FORMATTING IN THE CONSTRUCTION SAFETY ORDERS ......................................................................................................................... 2-17 CHAPTER 3 SOILS 3.0 INTRODUCTION............................................................................................................. 3-1 3.1 SOIL IDENTIFICATION, CLASSIFICATION, DESCRIPTION AND PRESENTATION ........................................................................................................................................... 3-1 3.2 SOIL PROPERTIES and STRENGTH............................................................................. 3-3 3.3 STANDARD PENETRATION TEST (SPT) .................................................................... 3-4 3.4 CONE PENETRATION TEST (CPT) .............................................................................. 3-6 3.5 FIELD and LABORATORY TESTS................................................................................ 3-8 3.6 SHEAR STRENGTH ........................................................................................................ 3-9 3.7 CONTRACTOR SOIL INVESTIGATIONS.................................................................. 3-10 3.8 SPECIAL GROUND CONDITIONS ............................................................................. 3-11 CHAPTER 4 EARTH PRESSURE THEORY AND APPLICATION i CT TRENCHING AND SHORING MANUAL 4.0 GENERAL ........................................................................................................................ 4-1 4.1 SHORING TYPES ............................................................................................................ 4-1 4.1.1 Unrestrained Shoring Systems .............................................................................4-1 4.1.2 Restrained Shoring Systems ................................................................................ 4-1 4.2 LOADING......................................................................................................................... 4-2 4.3 GRANULAR SOIL ........................................................................................................... 4-4 4.3.1 At-Rest Lateral Earth Pressure Coefficient (K0)................................................ 4-10 4.3.2 Active and/or Passive Earth Pressure ................................................................4-11 4.3.2.1 Rankine’s Theory ............................................................................. 4-11 4.3.2.2 Coulomb’s Theory ...........................................................................4-14 4.4 COHESIVE SOIL ........................................................................................................... 4-19 4.5 SHORING SYSTEMS AND SLOPING GROUND ....................................................... 4-24 4.5.1 Active Trial Wedge Method ..............................................................................4-25 4.5.2 Passive Trial Wedge Method .............................................................................4-27 4.5.3 Culmann’s Graphical Solution for Active Earth Pressure ................................. 4-28 4.5.3.1 Example 4-1 Culmann Graphical Method ......................................4-33 4.5.3.2 Example 4-2 Trial Wedge Method .................................................4-37 4.5.3.3 Example 4-3 (AREMA Manual page 8-5-12) ................................4-39 4.5.3.4 Example 4-4 (AREMA Manual page 8-5-12) ................................4-43 4.5.3.5 Example 4-5 (AREMA Manual page 8-5-13) ................................4-45 4.5.3.6 Example 4-6 (AREMA Manual page 8-5-13) ................................4-48 4.6 EFFECT OF WALL FRICTION ....................................................................................4-50 4.7 LOG SPIRAL PASSIVE EARTH PRESSURE.............................................................. 4-50 4.7.1 Composite Failure Surface ................................................................................. 4-52 4.7.1.1 Force Equilibrium Procedures .........................................................4-52 4.7.1.2 Moment Equilibrium Procedures ..................................................... 4-55 4.7.2 Noncomposite Log Spiral Failure Surface .........................................................4-60 4.7.2.3 Force Equilibrium Method ............................................................... 4-60 4.7.2.4 Moment Equilibrium Method ..........................................................4-61 4.8 SURCHARGE LOADS .................................................................................................. 4-70 4.8.1 Minimum Construction Surcharge Load ........................................................... 4-70 4.8.2 Uniform Surcharge Loads .................................................................................. 4-71 4.8.3 Boussinesq Loads............................................................................................... 4-72 4.8.3.1 Strip Load......................................................................................... 4-72 4.8.3.2 Line Load ......................................................................................... 4-73 4.8.3.3 Point Load ........................................................................................ 4-74 4.8.4 Traffic Loads .....................................................................................................
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