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Compaction Grouting

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Ahmed Atef

on 18 July 2016

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Transcript of Compaction Grouting

Introduction
- Definition

- History

- Applications
Definition
Compaction grouting as a ground improvement technique involves the injection of very stiff grout material under a high pressure and low rate, in order to densify the treated soils by radially displacing the soil particles into a closer spacing.
History
Compaction grouting, one of the few US born ground improvement techniques, was developed in the US, California in the 1950's, then transferred to Europe and the world in 1990's with more applications
Applications
•Increasing the Bearing capacity of soil
•Underpinning
•Reduce foundation settlements
•Reduce liquefaction and seismic subsidence
•potential, permit construction on loose granular fills
•Reduce settlements in collapsible soils
•Reduce sinkhole potential or stabilize existing sinkholes in karst regions.
•Cavity Grouting
Effect of Soil type
Compaction grouting is most effective in free draining granular soils, low sensitivity soils and cohesionless soils.

- The expected improvement achieved in specific soil types is shown.

The grout pipe is either installed by means of a drill rig or a vibro hammer, depending on the soil and on the treatment requirements.

The grout paste is prepared in the mixing plant and pressed into the soil , individual intersecting grout bulbs are consecutively formed creating column shaped elements.

In order to achieve a uniform compaction of the soil, the injections are at first executed in a large primary grid, and may be compacted further by means of a secondary grid.
Procedure :
1- Installation of the grout pipe
2- Compaction Grouting
3- Staged Compaction
Compacting Grouting Procedure and Sequence
Sequence :
A- Bottom Up Sequence
Compaction grouting is typically started at the bottom of the zone to be treated and proceeds upward.

The treatment does not have to be continued to the ground surface and can be terminated at any depth. The technique is very effective in targeting isolated zones at depth.

It is generally difficult to achieve significant improvement within about 8 ft. (2.5 m) of the ground surface.
Sequence :
B- Top Down Sequence
In this procedure, grout is first pumped at the top of the treatment zone. After the grout sets up, the pipe is drilled to the underside of the grout and additional grout is injected.

This procedure is repeated until the bottom of the treatment zone is grouted.

If the injection rate is too fast, excess pore pressures or fracturing of the soil can occur, reducing the effectiveness of the process.

This sequence is used when
- Injections are near the surface
- Adjacent sensitive structure
Note that :
- Jet grouting is more likely to be a load transferring technique

- Compaction grouting is more likely to be soil improvement technique
Compaction
Grouting

Submitted By :
Ahmed Atef Abdel-Fattah Maklad
Contact info : ahmedmaklad590@hotmail.com


Submitted To :
Dr : Adel El-Kelesh
Compaction Grouting Parameters
- Compaction Grouting Parameters, and how they influence the effectiveness of the compactions grouting process :
• Grout Hole Spacing
- For deep injectionSpacings of 2 to 4 m are frequently used
- For shallow injection, final spacing usually range from 1 to 2 m.
- Holes spaced too far apart will leave zones of undensified soil
• Injection sequence
- Grout is usually injected with (0.3 to 0.9) steps
- it can be performed from the top down (stage down) or from the bottom up (stage up).
- While stage up grouting is generally more economical
Compaction Grouting Parameters


Grout Injection Pressure and Rate
-Injection pressure varies from (1 to 7) MPA
-Injection rates Varies from (0.05 to 0.125) m3/min = (50 to 125) lit/min


Excessive injection rates and pressures will result in premature heaving of overlying ground. The maximum pressure also depends on the sensitivity of adjacent structures.
• Grout injection Volume
- Depends mainly on soil type
- uneven distribution of grout will likely result in uneven improvement
- Injection volumes range from as low as 4% of the treated volume to as high as 20% for sinkhole areas.
Other factors influencing the effectiveness of compaction grouting :
•Grout mix
•Earth pressure
Overlying ground will heave if overburden pressure is low, and injection pressure and rate are too high.
•Soil Being Compacted
Cohesive soils are harder to compact than cohesionless soils. The technique is not effective in thick, saturated clayey soils
Compaction grouting is to continue at each hole stage until one of the following criteria occurs:
(When to Stop !)
1-Surface heave caused by the current grouting stage exceeds a certain value

2-Maximum Peak pressure or greater occurs at the current stage.
(Shear Resistance of soil is overcome)

3-Casing is forced out of ground by back pressure.

4-Target grout volume for the stage has been met.

5-Grout breaks out elsewhere at ground level.

6-The grout can no longer be injected in soil
Materials (Grout Mix)
• Generally, the compaction grout consists of
Portland cement, sand, and water
, Additional fine-grained materials can be added to the mix, such as natural fine-grained soils,
fly ash
, or
bentonite
(in small quantities
in order to maintain The grout Compressive strength
).

• The grout strength is generally not critical for soil improvement, and if this is the case, cement has been omitted and the sand replaced with naturally occurring silty sand.
Bentonite should be prehydrated if used, in order to prevent Bleeding and segregation.
Equipment
Required
Bentonite should be prehydrated if used, in order to prevent Bleeding and segregation.


Grout Mixers


Piston Pumps


Auger drillers

Hoses and Fittings

Safety on Site

Casings Headers

Pressure Gauges
- Three primary pieces of equipment are required to perform compaction grouting, one
to batch the grout
, one
to pump the grout
, and one
to install the injection pipe.
- The pump must be capable of injecting grout under high pressure and low rate.

(A piston pump capable of achieving a pumping pressure of (9 MPA) under a rate of (0.05 m3/min)
- In some applications, ready-mix grout is used eliminating the need for on-site batching.
Quality Assurance and Control
• Slump testing and sampling for unconfined compressive strength testing is performed during production.
• The production parameters should also be monitored and documented, such as pumping rate, quantities, pressures, ground heave, and injection depths
- This can be done using a
Compaction Grouting Monitor
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
Quality Assurance and Control
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
•The Grout Mix should be monitored during construction

• The Ground Heave must be monitored during the construction process

• Post grouting penetration testing (CPT – SPT) should be performed between injection locations to verify the improvement of granular soil.

•Load Tests and Ultrasonic, can be performed after the construction process as a part of the Quality Control process.
Advantages and Dis Advantages
Of Compaction Grouting
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
Advantages
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
• Spoil is not excavated when columns are constructed.
• Minimum risk during construction
• Minimum disturbance to the structure and the surrounding ground.
• Compaction grouting can be combined with other ground modification techniques to increase in density, shear strength and bearing capacity of the soil.
• High production rates, 10 times faster than convention grouting.
• No harmful vibrations to nearby structures/ utilities.
• Significant reduction in soil permeability.
• Greater economy. Although compaction grouting is expensive, it frequently is the most economical method.
• Increasing the liquefaction resistance of layers of loose granular soils at depth.
Dis Advantages
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
Disadvantages include the need for more technical understanding of the
treatment mechanisms, and guidelines to predict treatment effectiveness.

• Relative ineffectiveness in stabilizing near-surface soils: where the overlying restraint is small.
• Prohibitive cost for some structures if the faulty soil is excessively deep.
• Grouting adjacent to unsupported slopes may be ineffective.
• Difficulty of analyzing results.
• Not valid in decomposable material.
• Challenging to verify improvement.
• Danger of filling underground pipes with grout.
• Questionable effectiveness in saturated clays.
• It is still a relatively more expensive option for most conventional ground densification treatments.
Limitations
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
• Abundant research has not been performed on compaction grouting and most design methods are largely empirical.

• Although some successful implementations have been performed and documented, the design of compaction grouted projects relies largely on experience and requires careful monitoring and extensive testing before, during, and after construction.

• Some ground heaving can be experienced when the installation methods and procedures are not customized to the in-situ soils, or where the soils vary greatly with depth

•Compaction grouting is especially susceptible to ground heaving near the ground surface where large overburden pressures are not present to resist the grouting pressures. High fine-grained soil contents can lead to hydro fracturing under the high pressures, and conversely large coarse-grained soils with high void contents can allow the grout to fill the pores instead of densifying the surrounding soil.
COMPACTION GROUTING APPLICATIONS IN EGYPT
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
• Compaction grouting was first introduced in 1997. Only one project was carried out under that name but adopting a technique modified from that described above. That case and another close one are presented below:


Golden Pyramid Plaza-Heliopolis Project
• This job was carried out for the construction of a hotel and shopping center over an area of 126,000 m2 at El-Nasr City. Piles were first suggested for the foundation. But isolated footings were preferred with soil improvement to increase the bearing capacity and reduce differential settlements and absolute settlements. The method chosen for site improvement was called
“Reinforced Computerized Compaction Grouting Method” or “Reinforced Compaction Grouting Columns” (RCGC).
COMPACTION GROUTING APPLICATIONS IN EGYPT
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
1-

Site Conditions:
• The site was medium to fine sand, poorly graded, slightly cemented with traces of silt or clay. This soil with different combinations extended to a depth 45 m. There were no signs of ground water over that depth. The average dry density was 1.7 t/m3. Four types of preliminary tests were performed; pressure meter tests, collapsibility test, two load tests, and five pull out tests.
2-

Grout Mix composition:
• The mix per m3 was: 1200 kg of sulfate resistant cement (SRC) and 600 kg water (i.e. Water/Cement = 0.5). The grout density ranged between 1.79 and 1.87 t/m3 and the viscosity ranged from 40 to 45 sec/ lit.
• Compressive strength at 3 days, 7 days and 28 days had an average of 165. 227 and 357 kg/cm2, respectively.
• Young's modulus of elasticity was increased by 50%
3-

Acceptance criteria:
Acceptance criteria were both bearing and settlement criteria:
• Net safe bearing capacity of 7 or 8 kg/cm2.
• Maximum allowable settlement of 12 mm.
• A differential settlement of 0.05% of the distance between loads.
References
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
RST Instruments Ltd.
www.rstinstruments.com


Ground Improvement Techniques
Ronald D. Andrus
Riley M. Chung
October 1995


Review of Compaction Grouting Materials for Soil Treatment Abhishek S. Shethji and C. Vipulanandan
Methods of Soft Ground Improvement
James D. Hussin

Keller Group plc (Compaction grouting)
Ground Engineering Contractors
www.keller.co.uk

Field Investigation into Effectiveness of Compaction Grouting
Adel M. El-Kelesh, M.ASCE1; Tamotsu Matsui, M.ASCE2; and Ken-ichi Tokida3

COMPACTION GROUTING IN SAND
Gehan E. Abdelrahman
Mahmoud S. Abdelbaki
Fatma A. Balige
Thank You
Questions ?
Design
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
•The common design approach of compaction grouting as a ground improvement technique assumes that the volume of injected grout directly reduces the volume of soil voids.

•An index representing the volume of soil voids that is replaced by grout and defined as the replacement ratio (ratio of the volume of grout to the volume of treated soil)(aSD) is used as a design criterion.

•The improvement of soil evaluated by comparing the pretreatment and post treatment penetration resistances of (SPT - CPT) Tests

•The obtained improvements appear inconsistent with the predicted ones, this inconsistency is essentially attributed to the oversimplified design approach that does not account for the effects of the soil properties
Parameters such as the injection rate, injection sequence, and grouting procedure. Little effort, however, has been made to investigate such effects.

•The increasing number and scale of compaction grouting applications have resulted in a great demand for a better understanding
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
Case Study
A Field test conducted at Tokyo International Airport to evaluate the effectiveness of treatment by compaction grout piles under well-controlled grouting conditions.
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
Test Procedure
•The field test described was conducted at Tokyo International Airport at the location shown in Fig.1

•The test consisted of 87 compaction grout piles injected in three cases of different pile diameters and spacing, as shown in Fig.2
•The grout used was a mixture of fines containing aggregate, cement, and water.

•The grout had a slump of 2.0–4.0 cm, and was pumped at an average rate of 0:03 m3= min.

•The piles of Case 2 were injected first, then those of Cases1 and 3

•The three cases are characterized in Table 1. As Shown
Fig .2
Table 1
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
Ground Conditions
A description of the general strata of soils treated by compaction grouting, as determined by the recovered SPT soil samples, is as follows:

1. Pavement: reclaimed soil (Bs) of gravel with sand overlain by asphalt that is 0.15 m thick; extends to a depth of approximately 1.45–1.80 m;

2. Fine sand (As0): fines content (Fc) ranges from 7 to 31%; fines are nonplastic and approximately from 1.45–1.80 to 8.70–9.00 m in depth;

3. Silty sand (As1): Fc ranges from 38 to 48%; fines are nonplastic and approximately from 8.70–9.00 to 9.90–10.25 m in depth; and

4. Sandy silt (Ac2): low plasticity with plasticity index (PI) ranges from 5.2 to 19.5, the groundwater level is approximately 1.13 m below the surface.
Ground Surface Displacement
•Fig. 4 shows the vertical displacements of the ground surface measured along the A-A and B-B lines because of treatment by Case 2. Also shown are the positions of L2-1 to L2-7 and the numbers of the piles after which the displacements were measured
Fig. 4
•Fig. 5 shows the vertical displacements measured during treatments by Cases 1 and 3 and reveals that the heave because of Case 1 is smaller than that because of Case 3. For both cases, heave was larger in the direction of injection (to the left and right for Cases 1 and 3, respectively).
Fig. 5
Compaction Grouting Monitor
- The Compaction Grout Monitor System provides operators and engineers real-time display of key grouting parameters to enhance the understanding of site conditions.

- It is invaluable in providing a permanent record of key grouting parameters for quality assurance, quantity documentation, pressure and flow readings.
Spt Results
•The SPT test is the most widely used test to evaluate the soil improvement because of compaction grouting.


•Fig. 6 shows a comparison between the pretreatment and posttreatment N-values of SPT for the three cases; also shown are the depth intervals of the grout bulbs and the general strata of soil profile.
(ΔN) is the Ground improvement
Fig. 6
•It's also important to control the Position and slope of the grout columns as a part of controlling the layout.
Faculty of Engineering
Zagazig University
Full transcript