BANGLADESH WATER DEVELOPMENT BOARD THE PEOPLE’S REPUBLIC OF BANGLADESH THE PROJECT FOR CAPACITY DEVELOPMENT OF MANAGEMENT FOR SUSTAINABLE WATER RELATED INFRASTRUCTURE IN THE PEOPLE’S REPUBLIC OF BANGLADESH FINAL REPORT ANNEXES SEPTEMBER 2017 JAPAN INTERNATIONAL COOPERATION AGENCY (JICA) IDEA Consultants, Inc. INGEROSEC Corporation GE EARTH SYSTEM SCIENCE Co., Ltd. JR 17-110 LIST OF ANNEXES ANNEX 1: Design Manual for River Embankment ANNEX 2: Construction Manual for River Embankment ANNEX 3: Operation and Maintenance Manual for Hydraulic Structures ANNEX 4: User’s’ Manual for O&M GIS Database ANNEX 5: Action Plan for Dissemination and Effective Use of Manuals ANNEX 1: Design Manual for River Embankment BANGLADESH WATER DEVELOPMENT BOARD THE PEOPLE’S REPUBLIC OF BANGLADESH DESIGN MANUAL FOR RIVER EMBANKMENT IN BANGLADESH September 2017 PREPARED BY THE PROJECT FOR CAPACITY DEVELOPMENT OF MANAGEMENT FOR SUSTAINABLE WATER RELATED INFRASTRUCTURE Table of Content PREFACE ................................................................................................................................................ 1 1. PREREQUISITES CONCERNING RIVER EMBANKMENT DESIGN ..................................... 4 2. BASICS OF EMBANKMENT DESIGN ....................................................................................... 7 2.1 Required Functions of Embankments (General) .......................................................................... 7 2.2 Types of Embankments .................................................................................................................. 11 2.3 Embankment Design Procedure ................................................................................................... 11 2.4 Alignment of Embankment ........................................................................................................... 13 2.5 Set-Back .......................................................................................................................................... 14 2.6 Design Crest Level .......................................................................................................................... 14 2.6.1 Design Flood Level ................................................................................................................. 16 2.6.2 Selection of Design Flood Occurrence Frequency ................................................................... 18 2.6.3 Free Board ................................................................................................................................ 22 2.6.4 Extra Banking .......................................................................................................................... 24 2.7 Crest Width ..................................................................................................................................... 27 2.8 Side Slope ........................................................................................................................................ 28 2.9 Berm and Borrow Pits ................................................................................................................... 28 2.10 Selection of embankment materials ........................................................................................ 29 2.11 Compaction .................................................................................................................................. 31 3. DESIGN SPECIFICATION .......................................................................................................... 32 3.1 Slope Protection work .................................................................................................................... 32 3.1.1 General ..................................................................................................................................... 32 3.1.2 Projection of block .................................................................................................................. 32 3.1.3 Design of Revetments for embankment slope ......................................................................... 33 3.1.4 Block placement with open join .............................................................................................. 37 3.1.5 Toe Wall (Foundation work for slope protection blocks) ........................................................ 38 3.2 Seepage Protection Works ............................................................................................................. 39 3.2.1 General ..................................................................................................................................... 39 3.2.2 Methods in Embankment Body for Seepage Protection .......................................................... 39 (1) Cross Sectional Expansion Method ..................................................................... 39 (2) Surface Covering Method.................................................................................... 40 (3) Drain Method ...................................................................................................... 40 3.2.3 Method in Foundation Ground for Seepage Protection ........................................................... 43 (1) Method for shallow permeable foundation .......................................................... 43 1) River Side Seepage Control Method ....................................................................... 43 (2) Method for intermediate permeable foundation ..................................................... 44 (3) Method for deep permeable foundation ................................................................. 44 3.3 Toe Protection Works and Foot Protection Works ...................................................................... 45 i 3.4 Transition zone works and Edge Wall ......................................................................................... 45 3.5 Design of Crossing Structure of Embankment ........................................................................... 46 46 4. VERIFICATION OF EMBANKMENT SAFETY........................................................................ 47 4.1 General ............................................................................................................................................ 47 4.2 Verification of Embankment Safety with respect to Seepage ..................................................... 48 4.2.1 Embankment failure caused by Seepage .................................................................................. 48 4.2.2 Seepage Line and Piping .......................................................................................................... 50 4.2.3 Circular Slip (Sliding) .............................................................................................................. 51 4.3 Verification of Embankment Safety with respect to Erosion ................................................. 54 4.4 Verification of Embankment Safety with respect to Earthquake .............................................. 55 4.4.1 General ................................................................................................................................. 55 4.4.2 Basic policy .......................................................................................................................... 55 4.4.3 Determination of potential for liquefaction .......................................................................... 56 4.4.4 Liquefaction judgment and embankment stability calculation ............................................. 56 4.4.5 Calculation of subsidence amount ........................................................................................ 57 4.4.6 Strengthening work method ................................................................................................. 60 4.5 Verification of Embankment Safety with respect to bearing capacity of foundation ground .......................................................................................................................................................... 60 4.5.1 General ................................................................................................................................. 60 4.5.2 Process of sliding failure due to insufficient bearing capacity of a soft ground .................. 61 4.5.3 Soil constants for circular slide calculation of soft ground .................................................. 62 4.5.4 Countermeasures for stability of embankment constructed on soft ground ............................ 63 Annex-1 Pilot Project Design Report Annex-2 Assessment on Earthquake Resistance of the Embankment Appendix Assessment on Stability of Existing Embankment which is subject to flood water ii Preface The Standard Design Manual, comprising information and guidelines necessary for detailed design of structures pertaining to flood management works, irrigation works, drainage and road works of BWDB, was compiled by BWDB based on various overseas texts, publications, manuals and designs, etc. in 1995. The Design Manual for River Embankment in Bangladesh (Below, referred to as “design manual”) is prepared after reviewing the concerned sections of the current Standard Design Manual that pertains to river embankment design while taking the following points into consideration. (1) Almost the entire national land of Bangladesh is spread out over the downstream floodplains of three major rivers, the Ganges