Deformation problem and Instability may occur in roads of katcha regions in Sindh during floods. Here an example (in 2010) in north region of Sindh, Pakistan by failure of Thori Bund which not only fail the system of Irrigation but massive destruction comes in result due to failure of Thori bund 1.21 Million houses were damaged and 2.33 Million people were died. Regarding to this major accident we should measure the stability of existing Bunds to avoid the Flood Problem

1. ANALYSIS OF FLOOD
PROTECTION BUND
FARHAN HUSSAIN WAGAN
IRRIGATION DEPARTMENT, SINDH, PAKISTAN.

2. Keywords:
Flood Protection Bund, Soil
Properties, Finite Element
Method, Plaxis 2D, Stability
Analysis, Pore Water Pressure,
Factor of Safety, Results.

3. ABSTRACT:
Deformation problem and Instability may occur in
roads of katcha regions in Sindh during floods.
Here an example (in 2010) in north region of Sindh,
Pakistan by failure of Thori Bund which not only fail
the system of Irrigation but massive destruction
comes in result due to failure of Thori bund 1.21
Million houses were damaged and 2.33 Million
people were died. Regarding to this major accident
we should measure the stability of existing Bunds to
avoid the Flood Problem.

4. … CONTINUE
In this sense, an example of Bund slope in katcha
region of Sindh near sehwan bridge which works as
Flood Protection (FP) bund during flood, To find the
stability we took soil samples from selected site and
measure by in situ tests and labority tests it
includes dry density test, sieve analysis,
permeability test, shear box test and Atterbergs
limits than measured values were putted in Plaxis
software which works on Finite Element Method.
Finally founded results are satisfactory regarding to
Pore Water Pressure and Factor of Safety which
was 1.7.

5. PROBLEM STATEMENT:
In Sindh, various roads are being constructed on katcha
regions along the route of river Indus. The roads are
constructed on embankments as high as 20-25 ft. These
embankments are mainly constructed of alluvial silts and
clays. In such road embankments, failure may occur when (i)
the flood is at highest level and (ii) immediately following the
recession of a flood. This is due to creation of potential shear
surface when pore water pressures remain high in the bank
after the flood water has been removed. Pore pressures
increase in the foundation and embankment body and as a
result shear strength decrease which may cause failure.
Such types of failures in road embankments located in flood
regions have occurred.

6. Figure shows overflow of water on Thori Bund

7. FAILURE OF BUND EMBANKMENT:
Action of flowing water through soil which may break loose
particles and transport them to new locations. This action
may cause geometric changes of a slope with serious
distress of complete failure of an embankment. When
water flows through soil in an embankment and
foundation, seepage forces act on soil particles. If
seepage forces acting in the soil are large enough as
compared to the resisting forces based on the effective
earth pressure, erosion occurs by washing soil particles
away from the surface, and piping successively develops
as erosion gradually progresses.

8. FINITE ELEMENT METHOD:
Finite element method is widely used in geotechnical
engineering for numerical analysis of various
geotechnical structures. With advancement of
computers, FEM is considered to be powerful when
it is used for analysis of slope stability with various
changes in geometry, soil and loading conditions.
The finite element method (FEM) is a numerical
procedure to obtain approximate solutions of
boundary value problems in all fields of
engineering.

9. PROPERTIES OF SOIL:
Regarding to engineering properties of soil as
Strength and Compressibility, plasticity of soil has
very important effect. Almost classification is based
on plastic consistency. Consistency of soil is its
physical characteristics at recorded moisture
content. The change in volume of saturated
cohesive soil is approximately proportional to a
change in moisture content.

10. PLAXIS 2D:
The Plaxis 2D is chosen for this study. The reasons
for selection of the Plaxis 2D are: (i) it is suitable to
analyse various geotechnical structures with
complex geometries, loading and boundary
conditions), (ii) it accounts for nonlinear material
behaviour, and (iii) in slope stability analyses
performed with the FEM, a failure surface is not
assumed in advance, instead, the failure surface
develops in those zones where the shear strength
of the soil is lower than the applied shear stresses.

11. PROPERTIES OF SOIL:
ATTERBERG’S LIMITS.
UNIFIED SOIL CLASSIFICATION SYSTEM (USCS).
MOHAR-COULOMB FAILURE CRITERIA.
PERMEABILITY TEST.
SHEAR BOX TEST.
DRY DENSITY TEST.
INSITUE TEST @ SITE.

12. OBJECTIVES OF RESEARCH:
 To analyze stability of a bund located in flood region
by considering the effect of flood water.
 To analyze with the help of numerical analysis
whether an existing bund located in flood region is
stable or not.

13. Figure shows Site view of case study
Figure shows site Model

14. Figure shows Water Level 3 m below Ground Level:
Figure shows Water level 3 m above Ground Level:
Figure shows Water Level 5 m above Ground Level:

15. Figure shows Maximum Pore water Pressure 9.5 KN/ m2at Present water level
3 m Below GL
Figure shows Maximum Pore water Pressure 13 KN/ m2 at Flood level at
3 m above Ground level

16. Figure shows Maximum Pore water Pressure 26 KN/ m2 at Flood level at 5 m above Ground level

17. Figure shows Maximum Pore water Pressure 36 KN/ m2 at Flood level at 7 m above Ground level

18. ANALYTICAL ANALYSIS:
To find stability of our research project manual
analysis was also performed to check and compare
values with Plaxis 2D software which is based on
Finite Element Method. Analysis was done through
method of slices which is one of the accurate and
reliable method.

19. … CONTINUE
 Draw Cross-Section to natural scale.
 Select failure surface
 Divide the failure mass into some slices
 Compute total weight (Wt) of each slice.
 Compute frictional resistance force for each slice
 Compute cohesive resisting force for each slice
 Compute tangential driving force for each slice

22. Figure shows Forces Acting on Each Slice.

23. Slices w/b  Φ Cohesion Pore Pressure Length
1 19 -1 24 15 4.9 2
2 57 2 24 15 15.2 2
3 95 5 24 15 22 2
4 129.2 15 24 15 17.16 2
5 144.4 19 24 15 7.6 2
6 144.4 31 24 15 0 2
7 71.25 40 24 15 0 1
8 56.06 52 24 15 0 1
9 41.8 58 24 15 0 2
Table shows Calculation for Factor of Safety of 3 m flood level Slope through Method of Slices

24. RESULTS:
A Flood Protection Bund was analyzed for different levels
of flood water and
 At different levels Factor of Safety was found 1.6, 1.4
and 1.3 for 3m, 5m and 7m flood water levels,
respectively.
 Analysis was carried out using a commercial finite
element program PLAXIS 2D.
 Over all present condition at site is satisfactory and
Factor of Safety was found 1.7.
 As expected the Factor of Safety reduced due to
increase in flood water level.
 For stability Factor of Safety should not be less than
1.5