CSM Cutter Soil Mixing

Equipment

Construction Procedure

PRODUCT INFORMATION 49e

PI 49e 8/2005-sd 2

Mixing head BCM

Types of wheels

The wheels are designed to cut and loosen the soil matrix and then to mix it with the slurry. The soil type dictates whether more emphasis needs to be put on the wheel’s cutting or mixing capability. In order to cover varying ground conditions, different types of wheels are available.

Type 1 Type 2 Type 3

non cohesive, sandy soil

in combination with short reamer

plates

non cohesive and cohesive clayey,

silty soil

in combination with long reamer plates

hard, dense soil including stones

short, long or no reamer plates

BCM 5 BCM 10

Torque 0 - 57 kNm 0 - 100 kNm

Rotation speed 0 - 40 rpm 0 - 35 rpm

Height 2,35 m 2,8 m

Panel length 2,4 m 2,8 m

Panel width 500 - 1000 mm 640 - 1200 mm

Weight 5100 kg (wheels 500 mm) 7400 kg (wheels 640 mm)

PI 49e 8/2005-sd 3

The BCM unit is supported by a Monokelly system. For smaller rigs and for a maximum depth of 12 m, the standard Kelly bar is round (Ø 368 mm). For extended depths, up to 35 m, a Kelly bar with a rectangular cross-section (600 mm x 340 mm) is used. With this cross-section the Kelly bar can, if necessary, be extended beyond the height of the drill rig mast. Two guide sledges connect the Kelly bar to the drill rig’s mast, they provide alignment, crowd and extraction forces and rotational movement. A hydrauli-cally operated locking mechanism transfers crowd and extraction forces to the Kelly bar and a rotating ar-rangement incorporated in the guides enables the CSM unit to be turned +45° to -90°.

Monokelly system

BG 18 H RG 16T / RG 19T BG 28

Panel depth 12 m 15 - 19 m 18 m

Engine power 173 kW 470 kW 300 kW

Extraction force 270 kN 200 kN 580 kN

Overall height 19 m 21,3 - 24,4 m 26,2 m

Operating weight 54 to 57 - 65 to 90 to

BCM (recommended)

BCM 5 BCM 5/BCM 10 BCM 5/BCM 10

circular

one string kelly

rotation facility

circular

one string kelly

rotation facility on

mast

rectangular multi-

section kelly

rotation facility

BG 18H RG 16T / RG 19T

19000

17

00

0

3920

3180 3000

264002

30

00

4070

BG 28

RG

16T

2930

RG

19T

3080

RG16T 3750

RG19T 3800

2230

RG16T 3500

RG19T 3700

RG

16T

21250

RG

19T

24400

RG

16T

17970 /

RG

19T

20140

PI 49e 8/2005-sd 4

Monokelly system

NIPPON SHARYO BG 28

Panel depth 35 m 30 m

Engine power 260 kW 300 kW

Extraction force ** 330 kN

Overall height 41,20 m 34,90 m

Operating weight ** 100 to

BCM (recommended) BCM 5 - BCM 10

rectangular multi-section kelly no rotation facility

** depends on model specifications

3753 5040

approx. / ca. 7300

32

50

0

41

20

0

87

00

34900

17196

NIPPON SHARYO DH 658 - 135

BG 28

PI 49e 8/2005-sd 5

Monokelly system (rectangular type)

The BCM cutter-mixer unit is held and guided by a Monokelly system. The kelly bar is rectangular (600 mm x 340 mm). The full string length is made of sectional pipes. The connectors can transfer all forces (especially bending moments resulting from the load case "assembling") and they are covered with protection shields to ensure a flush surface. Hy-draulic hoses and suspension pipes are located inside of the hollow kelly bar. The maximum length of the Mono-kellysystem is 30 m (for erection without additional crane) and 40 m (erection with auxiliary crane) The weight for a 30 m kelly (incl. hoses and inlet guide) is approx. 18 tons, for a 40 m kelly it is approx. 23 tons

1 Hose inlet guide

2 Flange connection

.

3 Hose couplings

4 / 5 Kelly bar guides and locking mechanism The kelly bar is guided and held with two sliding sledges. A hydraulically operated locking mechanism transfers crowd and pull forces onto the kelly bar. A twisting arrange-ment in the guides allows turning of the CSM unit from +45° to -90° locking device locking device (top) (bottom)

5

1

2 3

4

The kelly bar sections are connected with high quality screwed flange con-nections They can be covered with protection shield. Grooves in the protection shields allow locking of the kelly bar by cylinders of the holding system (4) All supply hoses can be coupled at the flange connections

PI 49e 8/2005-sd 6

Wire rope suspended system

For constructing deep panels, the mixing head BCM 5 and BCM 10 can be mounted at the bottom of a wire rope sus-pended guide frame (overall height 9 m) . For stabilising the unit side plates of the frame are extended during lowering of the unit and retracted during extraction of the unit for minimizing friction resistance in the mixed panel. For verticality control in x-direction the rotation speed of the wheels can be varied. For controlling the y-direction the inner frame can be tilted relative to the outer frame. Before mounting the system on a standard crawler crane, the suitability of the base crane has to be checked and con-

firmed.

Base Carrier

CBC 25

Base Carrier

BG

Base Carrier

Crawler crane

Hose handling system

HDS

Hose handling system

HSS

Hose handling system

HTS

Depth Depth Depth

80 m BG 28 38 m

BG 40 48 m

depends on type of

crane

e.g. HS 885 70 m

Extraction Lowering

PI 49e 8/2005-sd 7

Construction procedure

Mixing self-hardening slurries with native soils using a modified trench cutter technique is a new and effective method for

constructing:

• Cut-off walls.

• Earth retaining walls.

• Soil improvement.

CSM is used mainly for stabilizing soft or loose soils (non cohesive and cohesive), however the machinery used, derived

from Bauer’s cutter technology, extends the applicability of the method to much harder strata when compared to other

methods of soil mixing.

Main advantages of the method are:

• High productivity

• The in-situ soil is used as a construction material

• Very little generation of spoil (important factor in contaminated areas)

• No vibrations induced during construction (very important when working in soft soils in the vicinity of structures and

services)

• Extended depths (up to 80 m) can be reached - when using the rope suspended units.

Production rates are influenced by various boundary conditions:

Favourable conditions Unfavourable conditions

Soil structure uniform soil structure layered soil structure

Soil type loose to medium dense gravelly sand,

silty sand

dense to very dense soil, cobbles and boulders

embedded in soil, stiff or hard soil, cohesive or or-

ganic soil (reduction of the final strength)

Site geometry long, straight wall sections irregular wall layout

Wall depth wall depth > 10 m wall depth < 10 m (influence of non-productive peri-

ods such as moving, setting-up)

The construction process comprises the following sequence of steps:

Pre-excavation

Excavation of a guide trench for collecting surplus slurry (trench dimensions depend on site conditions. Recommended

size is 1,5 m wide, 1,0 m deep). The construction of a guide wall is not required. A guiding system is however recom-

mended, it could be in the form of a steel beam or similar structure. For weak surface conditions it is recommended to

use steel plates or similar as support for the base machine.

Mixing cycle

The mixing tool is driven into the ground at a continuous rate. The soil matrix is broken up by the cutting wheels and at the same time a fluid is pumped to the nozzles, set between the cutting wheels, where it is mixed thoroughly with the loosened soil. The direction of rotation of the wheels can be varied at any time. The preferred direction of rotation is from inside outwards. The rotating wheels and cutting teeth push the soil particles through vertically mounted shear plates that have the effect of a compulsory mixer. Penetration speed of the cutter and the volume of fluid pumped in are adjusted by the operator to optimise the ab-sorption of power and to create a homogeneous, plastic soil mass which permits easy penetration and extraction of the machine. The cutting and mixing cycles can be executed in two ways: Two phase system

During the penetration phase, cutting, mixing, fluidifying and homogenising is performed while pumping a bentonite slurry into the soil. The backflow of soil and bentonite can be pumped to a desanding plant where the sand is separated from the slurry that is re-cycled back to the machine.

shear�plate

slurry

PI 49e 8/2005-sd 8

truckremoval of backflow

panelguide trench

excavator

CSM rigsilos

bentonite and cement

with feed augers

mixer

agitator

cementdelivery

pump

air

compressor

HP 30

panelguide trench

CSM rig

desander

silos

bentonite and cement

with feed augers

mixer

agitator

bentonite

agitator

cement

delivery

pump

air

compressor

When the backflow becomes thick and no longer pumpable, it can be removed by a backhoe onto a screen where pri-

mary separation occurs. Using a Bauer Hose pump the fluid fraction is then pumped to the desanding plant unit for fur-

ther treatment.

After reaching the design depth, the flow of bentonite is replaced by a binder. Extraction of the machine begins and the

binder is mixed thoroughly with the fluidified soil. The speed of extraction and flow of binder are adjusted to ensure that

the total calculated quantity of binder is blended with the soil. The preferred direction of rotation is from outside inwards.

HP 30

mobile

sieve unit

panelguide trench

excavatorCSM rig

desander

silos

bentonite and cement

with feed augers

mixer

agitator

bentonite

agitator

cementdelivery

pump

air

compressor

Major advantages of the two-phase system are: • Increased safety when working at extended depths or when the working process is interrupted.

• Reduced wear and tear on the cutting wheels.

• Reduced cost for removal of spoil (a certain percentage of the slurry can be reused, the remaining spoil can be easily

removed as it is a dry material.

• Preferred application in difficult soil conditions, extended depths or for cut-off walls.

One phase system During the penetration phase, cutting, mixing, fluidifying and homogenising is performed while pumping the binder slurry

into the soil. As a rule of thumb you pump about 70 % of the total slurry volume during this phase. The backflow of soil

and binder slurry is collected in the pre-excavated trench or stored in a settling pond to be removed later off the site.

PI 49e 8/2005-sd 9

After reaching the design depth extraction begins and the remaining volume of binder slurry is blended into the soil. The

speed of extraction can be high as the majority of the binder slurry has already been mixed with the soil (penetration

phase).

Major advantages of the one-phase system are:

• No auxiliary desanding circuit required.

• Higher speed of extraction

• Preferred application in easy and uniform soils, depth range < 20 m, construction of retaining walls

Forming a continuous wall

A continuous wall is formed by a series of overlapping primary and secondary panels. Overcutting into fresh adjacent panels is called the “fresh-in-fresh method“. The CSM technique also performs the “hard-in-hard method“, where secon-dary panels cut into already hardened primaries - a typical sequence after work interruptions (weekends or holiday breaks).

Installation of reinforcement

Reinforcing elements, required for structural purposes, can be inserted into the completed wall. Normally steel stan-

chions are used. In shallow depths these will usually penetrate under their own weight; otherwise a light vibrator can be

used to assist their installation.

The distance between reinforcing elements and their size are designed on the basis of the applied loads and on the

results of the characteristic strength of the soil/binder mix.

Materials

Components of the binder

The components of binders normally used in the construction of CSM walls are: cement, bentonite, and water. It is pos-

sible also to use additives (if required) or admixtures (such as fly-ash)

Mix design and rate of consumption

The mix design is highly dependent upon: The application:

• Cut-off walls (permeability, strength, plasticity, erosion stability)

• Retaining walls (strength, permeability, plasticity of the fresh material, reinforcing)

The soil conditions: Particle size distribution, grain size, fines content, organic content, density, SPT values, porosity, groundwater level,

groundwater chemistry.

The mix proportions should always be determined by suitability tests prior to the start of construction. The following

tables give values for an initial design of the mix proportions. They should be used for reference only and must be con-

firmed by appropriate suitability tests.

2.200 - 2.800 mm 2.200 - 2.800 mm

2.200 - 2.800 mm

variable

P 1 P 2 S 1 500 - 1.200 mm

PI 49e 8/2005-sd 10

Wall characteristics

Cut-off walls Retaining walls

Compressive strength 0,5 - 2 MPa 5 - 15 MPa

Permeability approx. 1x10-8

m/sec

Auxiliary equipment

The list is intended as a guide for the auxiliary equipment required, or recommended, for uninterrupted work. kW

approx.

Slurry mixing station e.g. MAT SCW type, capacity not less than 15 m³/h

(depends on rig dimensions) 15

Delivery pump frequency controlled slurry pump with remote control,

capacity depends on volume of panel and speed of mixing.

typically: 200 - 400 l/min, 12 – 15 bars

30

Agitator tank approx. 3 - 5 m³ for the binder slurry 5

Silos for cement and bentonite with screw conveyors 2 x 5

Hydraulic backhoe for excavation of guide trench, maintenance of working platform,

handling of backflow 50

Hoses for conveying the binder or bentonite from the agitator to rig.

typically: 1,5” or 2” rubber hose (length to suit site requirements)

Agitator tank approx. 3 - 5 m³ for the bentonite slurry 5 2-phase system

HP Hose pump

(+ hoses)

pumping of reflux slurry from trench to desanding plant 20 2-phase system

Desanding plant for separating sand out of the reflux slurry e.g. Bauer BE 100 25 2-phase system

Mobile sieve unit located near the trench for pre-screening dense reflux slurry 10 2-phase system

Rig support steel plates or similar (depends on site surface condition) optional

Air compressor 7 - 14 bar / 7 - 10 m³/min 60 optional

Service crane +

vibrator

for inserting universal beams or other reinforcement into the

panel. Size of crane depends on length and weight of beams and

if a vibrator is also used.

Typical vibrator - RB 8000

60 optional

PI 49e 8/2005-sd 11

Quality control

Control of production parame-

ters displayed on the monitor of

the rig operator:

• Depth

• Volume

• Slurry pressure in hoses

• Slurry-soil pressure in trench

• Pumped volume vs. time

• Pumped volume vs. depth

• Inclination

• Speed of mixing tool

Documentation:

All production parameters are monitored, recorded and stored inside the rig throughout the construction process and can be printed out in the form of a quality assurance record for each individual panel.

Technical Specifications are subject to change without prior notice and incurring responsibility for machines previously sold. The shown

machines may have special equipment. Technical data do not consider power losses.

PI 49e 8//2005-sd 12

Site references

1 mixing in gravel (Italy)

2 circular kelly on BG (Italy)

3 excavated wall (Netherlands)

4 working in restricted conditions

(Netherlands)

5 CSM unit on Nippon Sharyo

(Japan)

6 excavated wall (Netherlands)

7 BCM 5 on RG 16T

1111 2222 3333

4444

5555

6666 7777