Dynamic compaction

1. Presented by:-
Gaurav Verma
IIT Roorkee

2.  Method invented and developed by Menard
Company in Late 1960’s
 Dynamic Compaction has been used on the
numerous sites all over the world for various
soil conditions and for a variety of
applications such as: roads, airports, large
halls

3.  Technique involves repeatedly dropping a large
weight from a crane
 Weight may range from 6 to 172 tons
 Drop height typically varies from 10 m to 40m

4.  Degree of densification achieved is a function of the energy
input (weight and drop height) as well as the saturation level,
fines content and permeability of the material
 6 – 30 ton weight can densify the loose sands to a depth of 3
m to 12 m

5.  Hook
 Boom
 Hoist Rope
 Kingpost
 Crawler
 Load cell
 Cab and
control
 Counter
weight
Hook
Hoist
rope
Boom
Kingpost
crawler
Load cell
Cab and
control
Counter
weight

6.  Dynamic compaction is done in 3 phases :-
 Phase one
 Phase two
 Phase three
 Each phase can have no of passes
primary, secondary, tertiary, etc.

7.  Spacing between impact points depend upon:
 Depth of compressible layer
 Permeability of soil
 Location of ground water level
 Deeper layers are compacted at wider grid spacing, upper
layers are compacted with closer grid spacing

8.  Deep craters are formed by tamping
 Craters may be filled with sand after each pass
 Heave around craters is generally small

9.  Applicable for all type of granular soil
 This technique is particularly well adapted to
non-organic, non-homogeneous fill and
reclamation areas with variable characteristics
 It is effective in both saturated and un-saturated
soils.
 The depth of the compaction most often
varies between 3.0 and 7.0 m.

10.  Expensive and time consuming
 Shock waves affect underground utilities in
developed areas
 The soil can be treated as close as 3 m from
underground services and can be treated 6 m
from the sound structures
 Causes environmental pollution by making
noise, gusts of air, vibrations