The Deep Mixing Methods Background andHistory of Usage in the U.S.

Dr. D.A. Bruce

Original Classification of Deep Mixing Methods(FHWA 2000)

Nature of MaterialPlaced

Mixing/BlendingPrinciple

Mixing/Blending Location

U.S. Examplese.g.,

SSM, SCC, Mectool

Hayward Baker

e.g.,DSM, Trevimix

Schnabel

e.g.,GeoJet

e.g.,Lime-Cement

Columns

DM Methods

Fluid Grouts Dry Materials

Rotary Rotary and Jet Grout

Shaft Mix End Mix End Mix

Rotary

End Mix

Conditions Favoring DMM

Ground is neither very stiff or very dense Ground has no boulders/obstructions Treatment < 120-foot depth Unrestricted overhead clearance Good and constant binder source Large spoil volumes can be tolerated Vibrations are to be avoided Treated soil volumes are large Performance Specifications applicable Treated ground parameters well defined

Example of Wet Rotary Shaft System

Example of Wet Rotary End System

Example of Dry Rotary End System

Example of Wet Jet End System

Low vibration, moderate noise. Applicable in most soil conditions. In appropriate conditions, good homogeneity and

continuity can be achieved.

Conventional (Rotary Vertical Axis) DMM

Particular Advantages

Productivities can be high 2,000/3,000 sf/shift. Unit prices are low -

moderate. Several good, experienced

contractors in the U.S.

Large, heavy equipment. Practical depth 110 feet (vertical). Method sensitive to very dense or stiff soil, organics,

boulders. Mobilization/demobilization costs high.

Conventional DMM

Potential Drawbacks

Updated Classification (Bruce, 2010)

3. Category 2 Cut-Offs (Mix in Place)

DMM (Deep Mixing Methods)

RotaryVertical

Axis

JetAssisted Vertical Axis (Turbojet)

Trench Cutting and Mixing

(TRD)

HorizontalAxis Cuttingand Mixing

WetEndMix

WetShaftMix

DryEndMix

Conventional

LowPressure(CSM)

High Pressure(CT Jet)

Conceived in 1993 in Japan. First used in U.S. in 2005. 170 ft. depth capability, 18-34 inches

wide. Continuous wall created by lateral

motion of vertical chain saw, installed in a predrilled hole.

TRD (Trench Re-Mixing and Cutting Deep Wall) Method

Blue print

Blades vary according to soil condition

A)Standard bladeB)Rounding blade for hard clayC)Long-nosed blade for boulder

A B

C

Continuous, homogeneous, joint-free wall in all soil and many rock conditions. Productivities can be extremely high (instantaneous

production > 400 sft/hour).

TRD

Particular Advantages

High degree of real time QA/QC. Adjustability of cutting teeth. Can operate in low headroom

(20 ft). Very quite, modest size support

equipment, clean operation.

Sharp alignment changes. Especially hard/massive/abrasive rock. Trapping of post in soilcrete or refusal on

boulders/rock. Only one (excellent) contractor!

TRD

Potential Drawbacks

Joint Bauer Maschinen/Bachy Soletanche development in 2003 Combines expertise in hydromill and deep mixing. Rapidly increasing in popularity worldwide (over 30

units in service). Similar system developed by Trevi (CT Jet). Maximum depth 180 feet, 20-47 inches wide.

CSM (Cutter Soil Mix) Method

The CSM machine is fitted with aset of instruments that convey tothe operator, in real time, all theinformation that is needed tomonitor and control quality of thework.

CSM Quality Control Systems

BAUER B-Tronic system

External pressure sensor

Instruments that read:

Verticality on X and Y axes

Torque on cutting wheels

Wheel speeds

Continuity assured by very strict verticality control. Very homogeneous product. Applicable in all soil

conditions (peat should be removed). Adjustable teeth.

CSM

Particular Advantages

A j CSM can be mounted on non-specialized carriers. Productivity can be very high. Can accommodate sharp alignment changes. Quiet and vibration free.

As for all DMM variants, rock, boulders and organics are challenges.

Needs considerable headroom. Cost base (as for all DMM variants).

CSM

Potential Drawbacks

Overview of Deep Mix Methods

Historical Background U.S.A.1986 SMW Seiko arrive in U.S.Late 1980s Jackson Lake Dam, WY (Seiko/GeoCon)Late 1980s Start of Environmental Applications (GeoCon)Early 1990s Start of Levee (Cutoffs) and Dam (Seismic)

Remediations1992-1994 First major Earth Retaining Structure (Boston, MA)1995 Visit by U.S. engineers to Japan1996 First Lime-Cement Column project

(New York)1997-1998 Largest wet DMM project to that time (Boston,

MA)1997-2000 FHWA State of Practice Studies2001-2005 National Deep Mixing Research Program

(States Funded)

Historical Background U.S.A. (continued)2000-2003 Desk, Bench and Field Tests, New Orleans2003 International Conference in New Orleans2005 Katrina and Rita2006 Task Force Guardian2006-2007 Deep Mixing at Tuttle Creek Dam, KS2007-Present National Deep Mixing Project Revised2008-Present Cutoff Walls at Lake Okeechobee2010-2011 LPV 1112012 International Conference in New Orleans

PHASE 1: DESK, BENCH AND FIELD TESTS 2000-2003 - Inner Harbor Navigation Channel (IHNC)

PHASE 2: TASK FORCE GUARDIAN (2006) AND LATER WORKS TO 2010

PHASE 3: LPV 111 (2010-2011)

Brief History of Deep Mixing in New Orleans

Phase 1 Original Field Test

Extraction of Column

Loading of Test Area

Katrina and Rita, 2005

Mission Statement (paraphrased):

To restore the flood protection to pre-Katrina levels by 1 June 2006.

Approximately 169 miles of levees and floodwalls repair work.

Task Force Guardian (2006)

Independent Technical Review

Phase 2 Work (Task Force Guardian 2010)

Orleans Avenue Interim Closure Structure

17th Street Canal Interim Closure Structure

Homeplace Levee Enlargement

IHNC Deep Mixed Cutoff Wall

Four TFG Projects (2006)

17th Street and Orleans Avenue Canal Closure Structures

Orleans Avenue

Flood SideProtected Side

Phase 2: Wet Mixing at Orleans Avenue

Phase 2: Dry Mixing at 17th Street Canal and Homeplace Levee

Phase 2: Dry Mixing at 17th Street Canal

Phase 2: Homeplace Levee Enlargement Plaquemines Parish

P24 Column LayoutPlan View

Homeplace Levee Enlargement (P24) (2006)

Inner Harbor Navigation CanalSeepage Cutoff Walls

During hurricane Katrina a substantial percentage of New Orleans East Levee System failed, including LPV111.

The Hurricane Protection Office of the US Army Corps of Engineers attributed the failure of the system to overtopping, erosion, and subsequent breaching of levees along the GIWW.

Phase 3: LPV 111

LPV 111 - Project Overview

In order to address the technical and logistical demands of the project, the deep mixing method was designed as the most suitable technology utilizing Early Contractor Involvement.

In order to prevent settlement of the additional overburden and resist potential lateral forces originated by storm surges, the ground improvement was designed to cover 30% of the new levee footprint to create rows of parallel buttresses, approximately 15 feet apart, perpendicular to the levee axis. In between adjacent buttresses, an individual element was installed to avoid differential settlement.

Large diameter single and double deep mixed columns were incorporated in the design.

The larger columns allowed the reduction of the total number of elements to be installed with obvious advantages for the highly demanding schedule.

Design

Design

Technology

Over 60% of the ground improvement was accomplished with the Trevi Turbo Mix technology, single and double axis.

The TTM method is a recent development of the deep mixing technology. It combines the injection of cement slurry at high velocity into the ground with mechanical mixing of the rotating blades.

The additional energy provided by the grout jets greatly improves the quality of the mixing of the soil with the grout and reduces the time required for the installation of the soil-mix columns.

Pre-Construction

The contract required that pre-construction activities be performed during the design phase to determine the most appropriate construction parameters and technical solutions:

Soil Investigation (2 phases) Desk Study Bench Scale mixing program (4 phases) Field Validation Test program (5+ phases)

Due to schedule constraints, only the first stages of the pre-construction activities were accomplished before the beginning of the actual production. The remaining stages were performed as work areas became available .

Production

PRODUCTION START DATE 1/14/2010PRODUCTION COMPLETION DATE 3/18/2011

TOTAL CALENDAR DAYS N 439.00 TOTAL MONTHS N 14.43

TOTAL SHIFTS WORKED (as of 3/18/2011) N 3,309 TOTAL MANHOURS (as of 3/18/2011) N 502,817

TOTAL DMM ELEMENT INSTALLED N 18,028 TOTAL VOLUME TREATED CY 1,681,579

TOTAL CEMENT USED SHTON 457,693 TOTAL TRUCK-LOADS (approx.) N 17,500

TOTAL WATER USED GAL 136,832,094TOTAL CORING N 506

TOTAL UCS TESTS N 5,082 OVERALL AVERAGE UCS (required = 100 psi) PSI 292

TOTAL FAILING UCS TESTS (

Construction

2x12 hrs/shifts, 5.5 days/week 6 dual auger + 2 single auger

rigs 8 active batch plants producing F\KURIJURXW

approximately 460,000 tons of cement used o 17,500 trucks

3 coring rigs over 500,000 man-hours in 14

months of production

LPV111 CHALLENGES:schedule logistics design soil characteristics size of the job

Phase 3: LPV 111

Dr. D.A. BruceDFI Deep Mixing SeminarApril 7-8, 2011

Conference Papers on LPV 111(New Orleans, February 2012)

Overview of Deep Mixing at Levee LPV 111, New Orleans, LA (Cali et al. (2012)

Deep Mixing Design for Raising Levee Section, LPV 111, New Orleans, LA (Cooling et al. 2012)

Construction Operations and Quality Control of Deep Mixing at Levee LPV 111 in New Orleans (Schmutzler et al. 2012)

Bench-Scale testing and Quality Control/Quality Assurance Testing for Deep Mixing at Levee LPV 111 (Bertero et al. 2012)

Use of Deep Mixing Return Material for Levee Construction at LPV 111 (Druss et al. 2012).

Enjoy the Seminar!