This Presentation deals with latest Ground improvement Techniques for various civil engineering projects like highway construction etc. and river side protection techniques.

1. Submitted by:-
Er.Abhineet godayal (B.Sc. Non Med.,B.Tech Civil, Mtech
Geotechnical Engineering)
Research in Geotechnical
Engineering

2. INTRODUCTION :-
 Ground improvement is the most imaginative
field of the geotechnical engineering. It is the field
in which the engineer forces the ground to adopt
the project requirements by altering its natural
state , instead of alter in design.
 The result usually include saving in construction
cost and reduction of implementation time

3. NEED TO IMPROVE GROUND..
 To reduce settlement of structure
 Improve shear strength of soil and thus
increasing bearing capacity of soil
 Increase the factor of safety against possible
failure of embankment.
 Reduce the shrinkage and swelling of soils
 Increase the liquefaction resistance

4. SIMPLE METHOD TO DESCRIBE
GROUND IMPROVEMENT
 Drop a handful of sand from certain height. You
will get a heap of sand. Keep your foot over it,
sand will disperse in all directions. Measure this
dispersion as ‘x’
 Drop again handful of sand on the leap of sand .
Keep your handkerchief on the top and then keep
your foot . Dispersion of sand will again be there ,
but less than previous one.
 Reason :- Friction developed between
handkerchief and soil due to which adhesion took
place between cloth and soil particles, thus soil
did not flow away

5. Research in the use of
Geosynthetic product
 Geosynthetics like geotextiles, geogrid,
geomembrane can lead to less deformation and
high strength to road and can reduce thickness of
the pavement
Functions Geotextile Geogrids Geomembrane Geocompos
its
separation √ - - -
filtration √ - - √
reinforcement √ √ - -
Drainage √ - - √
Erosion control √ - - -
Slope
protection
√ - √ -

6. Geogrids
 Geogrid are integrally polymer meshes. The
meshes are made of high tensile polymer
(HDPE/PP) and are totally on biodegradable and
anticorrosive. They have fused or thermally
welded joints having high dimensional stability
and strength. These grids are immune from
naturally occurring soil alkalies,acids and mineral
salts

7. Geogrid usage in road
construction

8. Techniques for Slope
Protection

9. Types of Riverbank Protection
 Vegetation
 Windrows and Trenches
 Sacks and Blocks
 Gabions and Mattresses
 Articulated concrete mattresses
 Soil-Cement
 Retaining Walls
 Many others possible

10. Fig. Showing Types of Riverbank
Protection

11. Vegetation - Main Types
 Shrub
 Trees
 Grasses

12. Vegetation Structure- Fascines
 Bundles of cuttings tied together, placed in
shallow trenches parallel to the bank
 Partially buried and staked in place
 Creates log-like structure that will quickly root,
grow and provide plant cover
 Holds soil in place to protect stream bank from
erosion

13. Stream bank Revegetation and
Protection

14. Windrows and Trenches
Conventional Windrow
placement
Trench

15. Sacks
 Filled with soil or sand-cement mixture
 Primarily used for emergency work during floods
 Protects stream banks when proper riprap isn’t
available
Advantages compared to stone riprap
 Allow placement on steep slopes
 Use locally available materials
 Creates smooth boundary
 Cobblestone effect may be more aesthetic

16. Sacks and Blocks
Blocks
Sacks
-Manufactured with local materials or obtained
commercially Cast with openings to provide for
drainage
-Openings also allow vegetation to grow so
that the root structure can strengthen the bank
-Can be used with a filter if erosion is a
concern
Advantages
-Durable, less susceptible to freeze/thaw
-Easy pedestrian access to river
-Low channel boundary roughness

17. Gabions

18. About Gabions
 Rectangular wire boxes (baskets) filled with
small-sized stones
 Used where flow velocities are too high for riprap
of small stones
 Made of heavy galvanized steel with PVC coating
for corrosive environments
 Stacked on relatively steep slopes to resist river
flows and unstable banks
 Need to be periodically inspected and maintained
from damage

19. Mattress Gabions
 Shaped into shallow, broad baskets tied together
side by side to form continuous blanket of
protection
 Placed on a smoothly graded riverbank slope
 May still allow some natural vegetation growth

20. Comparison between geogrid
reinforced section & unreinforced
section
 Unreinforced
Reinforced
 40 mm — Bituminous concrete — 40
mm
 75 mm — Dense bituminous concrete — 55
mm
 250 mm — Granular base(WBM) — 200
mm
 250 mm — Granular sub base —
235 mm

21. PROPERTIES COMMON TO
GEOTEXTILES
 Good resistance to chemicals
 Resistance to biological degradation
 Thermal stability 0 to 120˚c
 Material – 100% polypropylene
 Specific gravity- 0.91
 Weight/sq m-206-303gm/m
 Thickness-0.58-0.78
 Tear strength- wrap way-21-69kg
-weft way-18-71kg
 Breaking strength- wrap way-245-500kg
- weft way-181-333kg

22. PROPERTIES OF GEOTEXTILES
continued…..
 Pore size:- 60-243 microns
 Water permeability:- 4.2-55 litre/sec/metre
@ 10 cm water head