7. VARIOUS GROUND IMPROVEMENT TECHNIQUES
TREATMENT SHALLOW
LAYERS
TREATMENT OF DEEP
LAYERS
Compaction
Stabilization
Freezing & Heating
Geotextile
Reinforced Earth
CNS Layer
Dynamic compaction and
consolidation
Vibroflotation
Compaction pile
Blasting
Heavy tamping
Pre-compression – Vertical
drain
Electro Osmosis
Lime piles and columns
Stone columns
Grouting
8.
9. Dr. D.L.SHAH
Professor (Retd.), M S University of Baroda.
Senior Consultant, GEO DYNAMICS
Chairman, Indian Geotechnical Society – Baroda Chapter
Consultant to SSNNL, Govt of Guj.
dr_dlshah@yahoo.com
Grouting Technology for Civil
Engineering Applications
10.
11. Definition
Grouting is a process of injection of setting fluids in to
the voids of the alluvium, or into the fissures of the
rock either to reduce permeability or to increase
strength or both.
Injected fluid (grout) will solidify by physico-chemical
or by chemical action with the passage of time and
thereby increases the strength and reduces the
permeability.
The success of the grouting is mainly dependent on
selection and type of grout materials and suitable
grouting techniques.
14. Civil Engineering Applications of Grouting
Alluvial Grouting of Earth Dam Foundations
Alluvial Grouting of Building Foundations
Rock Grouting of Masonry and Concrete Dam foundations
Grouting During Pipe Jacking Operation
Grouting of Foundation Soils of Existing Machine Foundations.
Grouted Anchors.
Grouted Mattress for Seepage and Leakage Control in Perennial
Canal
Microfine Cement Grouting in Tunnelling and other
Applications
Crack Grouting for Rehabilitation of Building and Dams
Jet Grouting for Deep Foundations & Tunnels
15. Alluvial Grouting for Earth Dam Foundation
Concrete Gravity Dam with Intersecting Fault Zone
Concrete rch Dam
Resist Unstable
Movements
17. Vibration Isolation for Machine Foundation
Cement/Chemical injection of foundation media is a recent
innovation in decreasing vibration. Such injection results in
increased rigidity of the base and consequently increased natural
vibration of the foundation. Increased rigidity increases the
difference between the frequency of natural vibration and the
frequency of the machine. Consequently the amplitudes of
foundation vibration are decreased.
The injection method has the special advantages of non-interruption
of work of the machine during the treatment.
27. Jet Grouting
• A relatively new and one of the most successful techniques
• A speed jet of water released from a 1 to 2 mm nozzle at the
end of a grout pipe at a pressure of 200 to 5000 kg/cm2 cuts
through the soil or soft rock.
• When the slot has been formed, a chemical solution grout is
substituted for the water and stabilizes in place as a solid
mass.
• The grout pipe is lifted from bottom of the hole as process
continues.
33. An outline of Grouting from beginning
to end
•Investigation
•Decide whether grouting necessary or not
•Design
•Site preparation
•Equipment
•Drilling
•Water testing
•Hook-up
•Commencing grouting
•Looking for trouble
•Review of mix
•Completion
•Assessment
•Long term performance
41. The Lugeon Test
The Lugeon Test The most commonly in-situ test
used to estimate hydraulic conductivity of rock
masses is the Lugeon test – also called the packer
test. The test, which derives its name from
Maurice Lugeon (1933), is a constant head type
test that takes place in an isolated portion of a
borehole. Water at constant pressure is injected into
the rock mass through a slotted pipe bounded by
pneumatic packers. A pneumatic packer is an inflatable
rubber sleeve that expands radially to seal the annulus
space between the drill rods and the boring walls.
42. One Lugeon value, which is empirically defined
as flow rate of 1 liter/minute per meter of test
hole under a reference water pressure equal to 1
MPa
46. Use of Automated Data Acquisition System
Automated data acquisition systems capable of
measuring, displaying and recording Lugeon test
and grouting data in Real Time have become
available over the last years. This equipment
measures flow rate and pressure at regular
intervals of time and displays the information on
an LCD display.
47. • To give a sense of proportion for the
unit:
• 1 lugeon unit is the type of permeability
where grouting is hardly necessary.
• 10 lugeons warrants grouting for most
seepage reduction jobs.
• 100 lugeons is the type of permeability met
in heavily jointed sites with relatively open
joints or in sparsely cracked foundations
where joints are very wide open.
49. Adapting Grouting to Suit the Geology
Features that can influence grouting design and construction
include:
• 1. Spacing of Joints
• 2. Joint Widths and Continuity
• 3. Joint Inclination
• 4. Uniformity of the Site
• 5. Rock Soundness
• 6. Strength
• 7. Piping
50. 1. Spacing of Joints
As far as cement grouting
is concerned, it is the
open, groutable joints
that are of interest. If
they are widely spaced,
the grouting is usually
easier than if closely
spaced where troubles
such as frequent surface
leaks, collapsing holes
and patchy penetrations
can happen. These make
for more expensive grouting,
perhaps requiring special
surface treatment.
51. 2. Joint Width and Continuity
The easiest joints to grout
have widths in the range
between about 0.250 in [6
mm] and 0.020 in [0.5 mm].
Continuity of open jointing
systems affects penetration:
lack of continuity means
that more grout holes will
be needed than if grout can
travel appreciable distances
through the systems.
52. 3. Joint Inclination
Where dipping is mainly between 20° and about 60°, vertical grout
holes may give optimum interception. These are the easiest to drill
and are preferable. Steeper jointing usually requires use of
inclined holes.
53. 4. Uniformity of Site
Uniformity of jointing permits a regular layout
of grout holes, whereas irregular jointing,
dykes, disconformities, and so on may
require placement of holes at various
inclinations and spacing . Weaknesses may
need to be treated intensively.
54. 7. Piping
Where material in
joints can be removed
by seepage, either by
taking the material
into solution or by
eroding it, the
grouting will need to
be more intensive than
otherwise in order to
ensure that seepage
through such joints is
virtually eliminated.
55. Starting Mix Decided on:
• The recommended water:cement ratio is 2 : 1
for starting many of the grouting jobs. This is
two parts of water to one part of cement,
measured by volume.
• However, if the majority of cracks are known
to be relatively FINE such as 0.75mm or finer ,
starting with 3 : 1 could be better.
At the other extreme, If cracks are fairly
WIDE such as 1.25mm, it is usually wise to
start with 1 : 1. (W:C ratio by volume)
•
56. Fast Grout take
If the hole takes grout very rapidly, use
of a thicker mix can be warranted,
except in the special case where large
voids are present; the water test before
grouting should have indicated
whether such voids are present.
Usually, a fast take with minimal pressure buildup indicates that the
cracks will probably accept a thicker mix without blocking. Therefore
the grout should be thickened by one step and injected into the hole so
as to use the thickest practicable grout and thereby gain maximum
durability.
Further thickening of the mix might be warranted if grout behaviour
warrants this.
57. STANDARD MIXES and THICKENING STEPS
There is no need to use any other mixes than
5 : 1 by volume
4 : 1
3 : 1
2 : 1
1 : 1
0.8 : 1
0.6 : 1
0.5 : 1
58. When thickening the mix during grouting,
proceed down the list one mix at a time - never
jump a mix. For instance, if thickening from 3 : 1,
go to 2 : 1 for a while and then to 1 : 1 and
perhaps on.
Never go straight from 3 : 1 down to 1 : 1 or else
the too sudden thickening is liable to
prematurely block cracks in the job.
60. ROCK GROUT CLOSURE WHEN DOING CEMENT GROUTING
Closure grouting is the process of drilling and grouting the first holes
in an area fairly widely apart, then drilling and grouting a hole midway
between them, then putting holes midway in the remaining gaps, and
so on, continuing this process of halving centres until enough grouting
has been done.
The first holes are usually called
PRIMARY.
The holes midway between them usually
are given the name SECONDARY.
63. When grout holes are longer than about 30
ft [10 m], it is usually best to divide them
into shorter lengths, called stages, and
grout each of these stages separately.
77. Refusal Criteria
Each grout operation should continue until refusal is reached.
Refusal is considered to have been reached when
intact grout at the desired limiting pressure is less
than 2 lit/min averaged over a period of 10 minutes
and the pressure greater than 3.5kg/cm2, or 1 lit/min
when the pressure is below 3.5kg/cm2.
82. Marsh Cone – Oriffice Type Viscometer
Horizontal Flow Meter for
Flow measurement of Sand Cement Grout
Bleeding Test for Bleeding
Potential Mearuement
Water Retentivity Testing Set Up
83. Penetrability and Washout Test Set Up for
Seepage Study through Grouted sample
Grout Injection Mould for
Strength Measurement
86. The basic material should be as follows:
A powder readily soluble in water.
Inexpensive & derive in abundant supply.
Non toxic
Non corrosive
Non explosive
The grout solution should have:
A low viscosity solution
Stable under all normal temperature
Non toxic, non corrosive, non explosive
Catalyzed with common inexpensive chemicals
Insensitive to salts normally found in ground water
Of stable pH
Readily controlled for varying gel times
Able to withstand appreciable dilution with ground water.
87. The end product should be:
Permanent gel
Unaffected by chemicals normally found in ground water
Non toxic, non corrosive, non explosive
High strength
88. Since about 1970, silicate and acrylamide-based grouts share a
market percentage between 85% and 90%, with the remaining
portion of the market divided among other products. Chemical
grouts fall into the following categories:
Silicate formulations
Acrylics (includes acrylamide and acrylate grouts)
Lignosulfonates
Phenoplasts
Aminoplasts
Other materials
Chemical Grout Types
89.
90. ELECTROKINETIC GROUTING
• Electrokinetic grouting may be applied towards solidification of soil, reducing
its permeability and thereby increasing the strength of the soil.
– Definition: When a DC current is applied across a sandy soil mass or any
fine grained soil, sodium silicate (Na2SiO3) in the cathode compartment
and the reactants like calcium chloride (CaCl2) as a hardener in the anode
compartment migrate. The anionic silicate will migrate toward the anode
due to electro-migration and cationic metal ions will migrate toward the
cathode. When these charged ions meet within the soil, the pH of sodium
silicate will be reduced and thereby form a gel within the soil and grout
the soil mass. In silty soil where electroosmosis (pore water flow from
anode to cathode) occurs due to application of D.C. electric field, it is
expected that water-soluble sodium silicate grout will be carried away by
electroosmotic flow from the anode towards the cathode. When the pH of
this grout is reduced by the H+, generated and migrated (Electromigration)
from the anode, the sodium silicate grout will form a gel and stabilize the
soil.
91.
92.
93. • Electrokinetic Grouting may also be used to trap or immobilize the
contaminants within their host soil medium instead of removing
them through chemical or physical treatment; simultaneously while
densifying the soil.
94. SOIL TREATED BY ELECTROKINETIC GROUTING
• This method, an application of electrokinetic remediation
technique, was used to improve the geotechnical properties
of the soil mass by using a chemical grout. Soil was
compacted in model by hand compaction.
• At anode concentration used was made using 2% calcium
chloride (CaCl2) powder dissolved in tap water, whereas
at the cathode 20%, 25% and 30% sodium silicate
(Na2SiO3) dissolved in tap water was used for different
tests.
• These solutions were used as two different components of
a most commonly used chemical grout.
• Carbon electrodes were then placed and connected to an
AC- DC converter unit.
95. Model No. L (cm) H (cm) W (cm) Fill Height (cm)
o/p 1 8.3 19.8 10.2 15
o/p 2 18.2 19.5 15.5 15
o/p 3 25 19.8 20 15
o/p 4 41 22 30 15
Different size of open model
96. 98
Comparison of initial and final UCS of soil at different
locations
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
Anode Middle Cathode
UCS
in
kg/
cm
2
Before Electrokinetic Grouting
After Electrokinetic Grouting
98. Work at KAKRAPAR Canals in Gujarat
At the instructions of the Government of Gujarat, a Study has been taken
up by Cemindia, Bombay under World Bank Credit for adopting the
method of Grouted Mattress in India. For this purpose pilot testing have
been taken up at two sections of Kakrapar Canal system near Surat. The
canal has a maximum flow of about 250 cusecs and water depth of about
1.8 meters, having bed of about 6.6 wide and side slopes are 1 vertical to
1.5 horizontal.
99. Grouted Geotextile Mattress
Preamble
As a consequence of research and development jointly
by the Applied Mechanics Department & Textile
Engineering Department of Faculty of Technology &
Engineering and indigenous technique of GROUTED
GEOTEXTILE MATTRESS for canal lining under
flowing water condition was devised by R & D
Division of Cemindia. Model and field studies have
revealed that the strength of material in lining attained
at 28 days is about 180 kg/cm2 and the permeability and
rugosity co-efficient of lined canal are within the limit
of code of practice.
100. Technique
The technique involves use
of and mattress cove made
with two layers of a specially
woven synthetic fabric (Fig.)
Strip or threaded spacers are
provided in the dual walled
fabric which give the mat its
characteristics “cobbled”
effect.
The woven fabric is positioned on the prepared slope or surface
and subsequently filled with fine grained sand-cement grout mix.
The completed mat provides a slab of nominal 100 mm thickness.
Construction of the concrete matting starts with the positioning
and securing of the mattress on the ground profile.
101. Special pipes are then
inserted to the bottom of the
frame work. Colloidal sand
cement mix is then pumped
into position as the pipes are
gradually with drawn to the
surface. (Fig.) Pumping in
this way under low pressure
ensures continuity and
uniformity of the filter and as
the concrete mat is casted, it
adapts itself to the ground
profile. The mix is normally
used for pumping consists of
sand, cement and water.
102. Mattress fabric cover with spacer
A typical fabric developed for this purpose which involves special
three dimensional weaving technique. The fabric is a double layered
one and the two layers can be separated by a predetermined amount
with the help of spacer yarns. The spacer yarn ensures the continuity
of the two layers of the fabric shell as well as the thickness of the
lining without any hindrance to the fluid flow of the grout mix
during its application.
The length and distribution of the spacers yarn in total fabric matrix
can be manipulated to suit the specific requirements of the lining
thickness and grout pressure. To resist the pressure it is essential that
fabric shell possess sufficient tensile and bursting strength as also
low value of elongation at all levels of loading. The fabric is resistant
to acids, alkalis and other common chemical as also to weathering
and exposure to sunlight.
103. CHARACTERISTICS OF DOUBLE LAYER GEOTEXTILE88
1) Warp – Nylon yarn – Count – 1120 Deniers , Breaking load
– 7.36 Kgs. At 10 cms gauge length
2) Weft – Polypropylene flat Tape – Count – 1038 Deniers
Breaking load – 3.66 Kgs at 10 cms gauge length
%age Elongation – 41.83 %
3) Space Yarn –Nylon woven ape – Count – 7160 Deniers
Breaking load – 41.42 Kgs.
%age Elongation – 45.10 %
No. of ends and picks per inch 22
Two spacer yarns are used.
104.
105. The Canal perimeter was cleared of vegetation and trimmed to provide a
reasonably working surface. A canal perimeter is about 14.7 m. The mattress
length of about 15 m was laid, in the flowing water conditions, on the bed and
side slopes of the canal. It was properly secured along the edges. The next
length of the mattress was joined to the first 15 m length after completion of
the in-filling of the mattress. The joining of bed lengths was carried out in the
flowing canal. The mattress was filled up with a pumpable mix of cement-
sand – water and additives by the help of screw type pump. The nominal
thickness of the lining as achieved in about 11 cm. Tests carried out on
samples from the lining itself showed that the strength of the materials
attained at 28 days is about 180 kg/cm2.
106.
107.
108. Concluding remarks
It is essential to have good understanding of the
geologic conditions being treated by grouting. The
grouting program should be designed to address
those conditions and maintain sufficient flexibility
to accommodate new information obtained
following implementation. “Cook Book
Programme” will not suffice. The geologic,
grouting and permeability should be continuously
monitored so that appropriate changes in the
design can be made, and so that the impact of the
inevitable geological surprise can be minimized.
