1. Dr. Mohammad Shariful Islam
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-TEXTILES Abdul Jabbar Khan, Mohammad Shariful Islam, Abu Siddique, Roman Kabir and Shamima Nasrin
Dr. Mohammad Shariful Islam
Professor, Department of Civil Engineering,
Bangladesh University of Engineering and Technology (BUET)
Dhaka-1000, Bangladesh

2. River Bank Failure

3. Typical river bank failure
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
Structural Measure
Revetments
Guide bunds
Boulders
Brick matressing
Geo-bag dumping
Biological Protection
Bank Vegetation
Wood piling
Willow posts
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 APPROACH compounds 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
Geotextile
Large Particles
Fine Particles
Medium Size Particles
Rip-rap
Geotextile
Large Particles
Fine Particles
Medium Size Particles
Rip-rap
System-I
System-II

7. Formation of Filter Cake
Geotextile
Large Particles
Fine Particles
Medium Size Particles
Rip-rap
Geotextile
Large Particles
Fine Particles
Medium Size Particles
Rip-rap
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 Trials1
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
Name of River
Location
Facilitating Agency
Length (m)
Type of Flow
Maxm velocity (m/s)
HFL (m)
LFL (m)
Rainfall (mm)
Side
Slope
Maxm Scour Depth (m)
Pathoraj,
Panchagar
Northern part
BWDB
500
One way
1.5
63.5
60.7
2931
1:2
0.90
Gorai, Rajbari
Western part
100
1.6 –
2471
5.0
MBR Channel, Gopalganj
South part
200
Tidal
2.5
5.05
0.03
2105
1:3
9.72
Sakhbaria, Khulna
South-west part
400
3.35
-1.5
1734
13.0
Ghaghat, Rangpur
BWDB & SWO
750
2.0
32.5
27.6
BWDB: Bangladesh Water Development Board
SWO: Special Works Organisation

11. JGT USED IN RIVER BANK PROTECTION
River Name
Type of JGT used (gsm)
Condition of JGT
Pathoraj, Panchagarh
760
Bitumen Treated
Gorai, Rajbari
627
Additive Treated
MBR Channel, Gopalganj
Sakhbaria, Koyra, Khulna
Ghaghot, Rangpur
Untreated, Bitumen Treated

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

13. Additive Treated (627 gsm)
PROPERTIES OF JGT USED IN RIVER BANK PROTECTION
Parameter
Test Standard
Unit
Type of JGT
Description of Samples
Untreated
(627 gsm)
Bitumen Treated (760 gsm)
Bitumen Treated (627 gsm)
Additive Treated (627 gsm)
Mass per Unit Area
ASTM D3776
gm/m2
567
1177
860
638
Thickness
ASTM D1777 mm
1.86
3.24
2.46
2.27
AOS, O95
ASTM D4751* μm
<75
Vertical Permeability
(2 kN/m2) at 20°C
ASTM D4491
m/sec * 10-3
1.79
0.17
2.68
1.42
Grab Tensile Strength at 30°C
ASTM D4632 N
710/745 –
630/840
675/550
Grab Tensile Elongation at 30°C %
21/61
18/22
30/32
Wide Width Tensile Strength at
ASTM D4595
kN/m
20/17
35.4/
23.3
17/23
20/18
Wide Width Tensile Elongation at
11/9
15/17
12/12
CBR Puncture Resistance
DIN 54307
2830
4130
2930
2990

14. River bank prior to implementation of the trial
Pathoraj River Bank, Panchaghar
Characteristics
Value
Type of river
Mild
Type of flow
One way
Maxm velocity (m/s)
1.5
Highest flood level (m)
63.5
Lowest flood level (m)
60.7
Rainfall (mm)
2931
Bank Soil Type
Sandy Silt
Side slope
1:2
Maxm scour depth (m)
0.90
River bank prior to implementation of the trial

15. DESIGN OF RIVER BANK PROTECTION: PATHORAJ RIVER1 2 1m
CC Block (40 cm CUBE -60% or 30 cm UUBE -40%)
100 mm thick khoa filter
(40 mm to 20 mm & 20 mm to 5 mm), Well graded
Treated JGT
100 mm sand filter
(FM 1.0 to 1.5)
Volume of Launching Apron = 3.0 cum/m
3 m

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
Geotextile
Large Particles
Fine Particles
Medium Size Particles
Khoa filter
2nd Monitoring
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. River bank prior to implementation of the trial
Gorai River Bank, Rajbari
Characteristics
Value
Type of river
Mild
Type of flow
One way
Maxm velocity (m/s)
1.6
Highest flood level (m) –
Lowest flood level (m)
Rainfall (mm)
2471
Bank Soil Type
Clayey Silt
Side slope
1:2
Maxm scour depth (m)
5.0
River bank prior to implementation of the trial

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

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

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

27. River bank prior to implementation of the trial
MBR Channel, Gopalganj
Characteristics
Value
Type of river
Mild
Type of flow
Tidal
Maxm velocity (m/s)
2.5
Highest flood level (m)
5.05
Lowest flood level (m)
0.03
Rainfall (mm)
2105
Side slope
1:3
Maxm scour depth (m)
9.72
River bank prior to implementation of the trial

28. MBR Channel, Gopalganj

29. River bank prior to implementation of the trial
Sakhbaria, Koyra, Khulna
Characteristics
Value
Type of river
Mild
Type of flow
Both way
Maxm velocity (m/s)
1.5
Highest flood level (m)
3.35
Lowest flood level (m)
-1.5
Rainfall (mm)
1734
Side slope
1:2
Maxm scour depth (m)
13.0
River bank prior to implementation of the trial

30. Sakhbaria, Koyra, Khulna

31. River bank prior to implementation of the trial
Ghaghat, Rangpur
Characteristics
Value
Type of river
Mild
Type of flow –
Maxm velocity (m/s)
2.0
Highest flood level (m)
32.5
Lowest flood level (m)
27.6
Rainfall (mm)
2931
Bank Soil Type
Silty Sand
Side slope
1:2
Maxm scour depth (m)
3.0–4.0
River bank prior to implementation of the trial

32. DESIGN OF RIVER BANK PROTECTION: GHAGHAT RIVER1 2 1m
CC Block (40 cm CUBE -60% or 30 cm UUBE -40%)
100 mm thick khoa filter
(40 mm to 20 mm & 20 mm to 5 mm), Well graded
Treated JGT
100 mm sand filter
(FM 1.0 to 1.5)
Volume of Launching Apron = 3.0 cum/m
3 m

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