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Dr. Mohammad Shariful Islam Professor, Department of Civil Engineering,

National Seminar on the Project: Development and Application of Potentially Important Jute Geo-textiles (CFC/IJSG/21) 1 st April 2014, JDPC, Dhaka.

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Dr. Mohammad Shariful Islam Professor, Department of Civil Engineering,

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  1. National Seminar on the Project: Development and Application of Potentially Important Jute Geo-textiles (CFC/IJSG/21) 1st April 2014, JDPC, Dhaka PERFORMANCE EVALUATION OF RIVER BANK PROTECTION USING JUTE GEO-TEXTILESAbdul Jabbar Khan, Mohammad Shariful Islam, Abu Siddique, Roman Kabir and ShamimaNasrin Dr. Mohammad Shariful Islam Professor, Department of Civil Engineering, Bangladesh University of Engineering and Technology (BUET) Dhaka-1000, Bangladesh

  2. River Bank Failure

  3. Failure Mechanism of River Bank Erosion Failed surface Cause I EROSION IS CAUSED BY WAVE ACTION Failed surface Cause II Typical river bank failure EROSION IS CAUSED BY SOIL LOSS DUE TO HIGH SEEPAGE FORCE

  4. Common Practices for River Bank Protection • Biological Protection • Bank Vegetation • Wood piling • Willow posts • Structural Measure • Revetments • Guide bunds • Boulders • Brick matressing • Geo-bag dumping Rigid structural protection system is widely used. Unfortunately our national budget is never sufficient which confines rigid structural protection measures to the most acute sections, never to the full length of the river bank or coastline and embankment. This BANDAGE APPROACHcompounds the problem.

  5. Protection Against River Bank: Formation of Filter Cake • The environments in which geotextile filters have to perform can be divided into three categories, based upon the flow conditions: • a) Fairly steady unidirectional flow • b) Reversing flow with a moderate cycle time • c) Reversing flow with a very short cycle time • Where the flow is unidirectional • - the filter effect is not confined to the geotextile but spreads to the adjacent soil. • some loss of fine soil particles occur through both aggregate based filters and geotextile based filters when they are subjected to water flow. • the loss of fine material from the natural soil will be greatest immediately adjacent to the geotextile sheet, leaving a zone where the remaining larger soil particles bridge over the geotextile pores. These comparatively large soil particles will restrain slightly smaller soil particles which will in turn restrain even smaller soil particles. • This causes the formation of a graded filter structure known as “Filter Cake” in the zone of soil in contact with the geotextile. After the formation of this soil filter cake, geotextile filter becomes redundant.

  6. Formation of Filter Cake Rip-rap Rip-rap Geotextile Geotextile Medium Size Particles Large Particles Large Particles Fine Particles Fine Particles Medium Size Particles System-I System-II

  7. Formation of Filter Cake Rip-rap Rip-rap Geotextile Geotextile Fine Particles Fine Particles Large Particles Medium Size Particles Medium Size Particles Large Particles System-III System-IV ONCE THE FILTER CAKE FORMS, THE JGT FILTER IS NOT REQUIRED ANYMORE. SO, BIODEGRADIBILITY OF JGT IS NOT A PROBLEM, (JMDC 2008).

  8. River Bank Protection System Used by BWDB Geotextile filter replacing a multi-layer granular filter in a bank protection system Bonded rip-rap protection system for canal side Extended toe of rip-rap protection system, to deal with scour

  9. Locations of River Bank Protection Trials 1 Possibility of using JGT in 11 river bank sites were investigated. Among these, 5 sites have been selected for field trails, situated at various geographic locations with varying soil conditions. Sites are: 2 1. Pathoraj, Panchaghar 2. Ghaghat, Rangpur 3. Gorai, Rajbari 4. MBR Channel, Gopalganj 5. Sakhbaria, Koyra, Khulna 3 4 5

  10. DETAILS OF SELECTED RIVER BANK SITES BWDB: Bangladesh Water Development Board SWO: Special Works Organisation

  11. JGT USED IN RIVER BANK PROTECTION

  12. JGT USED IN RIVER BANK PROTECTION Additive Treated JGT Bitumen Treated JGT

  13. PROPERTIES OF JGT USED IN RIVER BANK PROTECTION

  14. Pathoraj River Bank, Panchaghar River bank prior to implementation of the trial

  15. CC Block (40 cm CUBE -60% or 30 cm UUBE -40%) 1m 100 mm thick khoa filter (40 mm to 20 mm & 20 mm to 5 mm), Well graded Treated JGT 1 100 mm sand filter (FM 1.0 to 1.5) 2 Volume of Launching Apron = 3.0 cum/m 3 m DESIGN OF RIVER BANK PROTECTION: PATHORAJ RIVER

  16. Pathoraj River Bank, Panchaghar JGT Application: June-July, 2011 1st monitoring: January, 2012 2nd monitoring: April, 2013

  17. MONITORING • PVC pipe with: • 1.20 m long • 50 mm diameter

  18. RESULTS (GRAIN SIZE DISTRIBUTION) Chainage : 1657 m Chainage : 1657 m At implementation time After six months of implementation Chainage : 1657 m After twenty four months of implementation

  19. RESULTS (FINENESS MODULUS) Chainage : 1190 m (beneath JGT) Chainage : 1230 m (beneath JGT)

  20. RESULTS (FINENESS MODULUS) Chainage : 1657 m (beneath JGT) Chainage : 1070 m (beneath SGT)

  21. RESULTS (FINENESS MODULUS) Before Implementation 1st Monitoring Chainage : 1657 m Chainage : 1657 m Khoa filter Geotextile Large Particles Fine Particles 2nd Monitoring Medium Size Particles Chainage : 1657 m

  22. DISCUSSION • Considering the first monitoring (investigation after six months), from the grain size distribution curves and FM it was found that in case of three samples, soil particles of the outside layer or near JGT are coarser than the particles of middle and inside soil layer. So, it can be said that, filter cake has been formed partially. • (2) Considering the second monitoring(investigation after two years), from the grain size distribution curves and FM it was found that in case of one sample, soil particles of the outside layer or near JGT are coarser than the particles of middle and inside soil layer. So in this case it can also be said that, filter cake has been formed partially.

  23. Gorai River Bank, Rajbari River bank prior to implementation of the trial

  24. CC Block (400×400×200) 1m 100 mm thick khoa filter (40 mm to 20 mm & 20 mm to 5 mm), Well graded Treated JGT 1 2 100 mm sand filter (FM 1.0 to 1.5) 0.7m (minm) 1.4m (minm) Extended portion of JGT = 1 m 14.0 m DESIGN OF RIVER BANK PROTECTION: GORAI RIVER

  25. Gorai River Bank, Rajbari JGT Application: June-July, 2013 1st monitoring: October, 2013

  26. 1st MONITORING 31.10.2013 JGT was found in good condition

  27. MBR Channel, Gopalganj River bank prior to implementation of the trial

  28. MBR Channel, Gopalganj

  29. Sakhbaria, Koyra, Khulna River bank prior to implementation of the trial

  30. Sakhbaria, Koyra, Khulna

  31. Ghaghat, Rangpur River bank prior to implementation of the trial

  32. CC Block (40 cm CUBE -60% or 30 cm UUBE -40%) 1m 100 mm thick khoa filter (40 mm to 20 mm & 20 mm to 5 mm), Well graded Treated JGT 1 100 mm sand filter (FM 1.0 to 1.5) 2 Volume of Launching Apron = 3.0 cum/m 3 m DESIGN OF RIVER BANK PROTECTION: GHAGHAT RIVER

  33. CONCLUSIONS It is found that partial filter cake was formed within six month of JGT application. Although Bitumen treated JGT was decomposed in six months time, the additive treated JGT was found in good condition. So, it can be said that JGT is effective until the filter cake is formed for natural protection of the river bank.

  34. Thank You

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