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Creating new spaces for humanity and the planet, from lessons learned from the earth.
All structures that we unconsciously use in our life such as buildings, bridges
and roads are built on top of the ground.
However, we cannot see the characteristics of the ground by observing it
from surface.
To prevent disasters that bring serious damage of structures such as uneven
settlement of ground or collapse of a cliff, it is necessary to know the charac-
teristics of the ground and reinforce it if necessary to suit it to the condition of
upper structures.
Fudo Tetra developed the world’s first Sand Compaction Pile method in
1950’s, and in present, it is reputed the representative ground improvement
method. Since 1950’s, we have kept researching and development with accu-
mulation of the design and the construction experiences and have got a reputa-
tion as an expert of the ground.
Through these long-lasting researches of ground improvement technologies,
we aim at providing safe ground to every structure and create environmentally
friendly society.
We provide most suitable and safe ground for any structures.
0101 02
Ideas from the EarthGround Improvement
by Fudo Tetra
Ground stabilization Reuse of construction materials and industrial by-products
Preservation, purif ication, and restoration of soil and groundwater
Fudo Tetra employs a diverse range of ground improvement technologies to provide foundations that are opti-mally suited to structures. Using technologies that have been culti-vated over many years, technological innovation is carried out at all times to offer the cutting-edge methods. These new methodologies are regis-tered with the New Technology Infor-mation System (NETIS) at the Minis-try of Land, Infrastructure and Trans-port , whi le e ffor ts are made to improve their credibi l i ty through means such as the acquisition of technical review certifications from public organizations.
Sludge, coal ash, concrete, and other materials generated at con-struction sites are reused as materi-als for ground improvements.
These technologies are used for pro-tecting soil and groundwater against pollution, and contribute to growing creatures and plants.
NETIS registrations: 20Candidate for recommendable technology in 2008
SAVE Compozer
Review certifications acquired:11(as of March 2009)
Earthquake-resistant measure of existing structures
We propose ground improvement methods that increase earthquake-resistance of foundation beneath the existing structures without interrupt-ing their operations.
Meeting the needs for sophisticated utilizations of urban spaces
We propose ground improvement methods that refresh structures with maintaining their functions and match with the trend of large-scaling and deepening of structures.
Development of new construction methods
We develop new construction meth-ods that are conformable to any con-ditions.
03 04
Fudo Tetra provides technologies that respond to a variety of construction needs with aims to create safe foundations and better environments.
SAVE-SP methods
X-jet methods
Super jet methods
Total Recycling System
Georaft method
Resoil method
Barge Consolider System
Ecogaia Stone, etc.
JACSMAN PJ methods
F-twin Jet method
X-jet methods
Super jet methods
TRD method
Fluidized Soil Placement method,
etc.
Triner method
Geolock method
Soil Restoration method, etc.
Compact construction equipmentConstruction equipment that reduces vibration, noise and displacementConstruction equipment that has higher productivityConstruction equipment that has higher efficiencyQuality control deviceSecure and reliable construction equipment
Ground Improvement by Fudo Tetra
Constructionachievements
Since 2005, we have resumed overseas business. By using our in-house methods, we have successfully completed 10 proj-ects in the U.S.A. and 7 projects in Viet-nam (as of April 2011). In the U.S.A., we carr ied out Sand Compact ion Pi le (Compozer) method and SAVE Compozer method for densification of loose sandy ground as a countermeasure against liquefaction during a seismic event. In Vietnam and in US New Orleans, we performed Cement Deep Mixing method for consolidation of soft clayey ground to stabilize and prevent settlement of the upper structures such as ports and harbors, levees, and power plants.
Craftsmanship on land and foundation
Overseas Business
Fudo Tetra creates foundations that are highly reliable, safe, economical, and environmentally friendly.
05 06
Foundations created by the Total Foundation Engineering System that depends on various reliable backgrounds are op-timally suited to the structures and people who use them.
Required performance of structureGround conditions Conditions for construction work
TOTAL FOUNDATION ENGINEERING SYSTEM
Planningcapability
Proposal for optimally suited foundation
Basicresearch
Technologydevelopment
Designperformance
Constructiontechnology
Constructionexperience
and know-how
Investigations and tests are conducted by utilizing state-of-the-art technologies.
This is ground survey equip-ment with superior mobility capable of performing accu-rate surveys by automatic recording of successive readings for the strength of the ground. Other equip-ments including cavity survey system, etc. are available.
A highly reliable con-struction management system that provides instructions to operators, based on analysis of al l construct ion factors by the computer system. Other systems including positioning systems using GPS, etc. are available.
■Investigative technologies
■Design technologies
■Computerized construction work
Booster (Ground survey equipment)
CONOS (COmpozer Numerical Operation Supporting system)
A diverse range of problems relating to grounds are solved by our engineers, who have doctorates and professional engineer qualifications, by using supe-rior information they obtained through participation in the committees of academies, official and statu-tory organizations, and private research institutes, along with a broad perspective and through the implementation of proprietary technologies.
Information processing is used for construction certainty, flexibility in responding to changes in conditions, along with safe operation and cost reduction.
Guaranty of performance and quality
Our “TOTAL FOUNDATION ENGINEERING SYSTEM” has been widely acknowledged overseas and has obtained successful reputations through various overseas construction projects.
Fudo Tetra’s overseas base and project location
Overseas Base (Subsidiary, Residence Office)Project Location Project Location (before 2005)
Cement Deep Mixing work on barge in Vietnam
CI-CMC work in New Orleans, Levee Construction US
Exposed top of Cement Deep Mixing Piles in Vietnam
SAVE Compozer work in California, US
In-land Cement Deep Mixing work in Vietnam
Tools supporting the TOTAL FOUNDATION ENGINEERING SYSTEM
Optimum foundation
Humanresources
SafetyInformation
SocialenvironmentEconomy
Ground Improvement by Fudo Tetra
A series of SAVE methods that prevent liquefaction of ground
Effort toward participation in architectural work
Effort toward participation in urban civil work
Densification of ground has received higher reputation in preventing liquefaction of the ground during seismic event. Especially, Compozer (Sand Compaction Pile method) is the world’s first densification method that was developed by us and has been widely used for various purposes in many loose grounds such as reclaimed ground.Since Compozer work needs vibration, applicable environment for Compozer is lim-ited. Therefore, SAVE Compozer has been developed for the application at an urban environment. SAVE Compozer, the densifi-cation method with no vibration and low noise and thereby is applicable adjacent to an existing structure, has many project his-tories and is selected as “2008 Recom-mendable Technology” in New Technology Information System (NETIS) by Ministry of Land, Transport and Infrastructure.Furthermore, SAVE Compozer has kept innovating and consequently given birth to SAVE Marine method that is an offshore type SAVE Compozer and SAVE-SP method that is applicable to the densification of ground beneath the existing structure.
We deeply understand characteristics of the ground and function of the upper structure, and reinforce the ground as a foundation of buildings.We provide exclusive methods for the treatment of building foundations.
The demand of upgrading of urban facilities such as enlargement of structures and utilization of deeply underground space requires higher construction technologies.We propose various sophisticated technologies such as more compact equip-ments, methods with low vibration, noise and displacement, methods that ap-plications adjacent to and contact with the existing structure are feasible, and these technologies satisfy strict requirements in urban civil work.
Quiet compaction, which does not rely on vibrating energy, is realized through the devel-opment of a rotary press construction method (wave construction method) that utilizes a forced penetration and withdrawal equipment with new structural configurations. This method is suitable for constructions at a site in proximity to existing structures.
SAVE Compozer (static sand compaction pile method)
SAVE Marine method(Non-vibrating, low-noise-type offshore Compozer)
A diverse range of construction equipment and mixing methods that respond to each kind of foundation and every type of construction size are adopted, in order to increase the strength of the foundations supporting structures through the creation of improved columns with a high strength and uniformity. This technology has been awarded the BCJ Assessment Certification No. 75 for Technology Assessment Certification of Building Construction Technology” (June 5, 2005) by the Kensetsu Center of Japan.
This method is used to create compacted sand piles without vibration and with low noise, as it uses non-vibrational forced penetration and withdrawal equipment and rotary equipment. This method is suitable for the waterside work such as reinforcement of a foundation for seawalls.
By using this method, the pumping and injec-tion of fluidized sand into ground through ultra-compact equipment accomplishes com-paction of the surrounding ground. This method realizes compaction of ground at narrow area and beneath the existing struc-ture.
SAVE-SP method (static ground compaction by sand injection)
These are the methods that combine mechani-cal mixing system and jet mixing system and have advantages of both systems with com-pensating disadvantage of each system.Complete improvement without remaining untreated area is possible.And improvement by contacting with existing structure is easily achieved.
JACSMAN and PJ methods (composite mixing methods by using cross jet)
This jet mixing method involves the discharging of slurry at ultrahigh pressure with large flow rates. The X-jet method can be used for ground improvements with a substantially superior quality and can be implemented with control on the diameter of the improved ground, made possible by the development of the cross jet method. Superior perfor-mance is delivered for protection of exit and entrance of shield machine from/to the shafts, shaft bottom improvement, kicker slab formation, and temporary earth retaining wall at discontinued part of the original walls due to existence of underground utilities.
F-twin jet method, X-jet method and Superjet method (high pressure jet mixing methods)
By t he i n s t a l l a t i on o f concrete piles into ground through SAVE Compozer procedure, densification of the surrounding ground is achieved to prevent lique-faction of the ground during seismic event, while the instal led concrete pi les increase bearing capacity of the ground.
Georaft method (Fluidization and backfill process of excavated soil with high strength and superior quality)
This is a new foundation method that ut i l izes demol ished concrete as an aggregate of fluidized backfill processing material for the building foundation.By adjusting specific gravity of fluidized mud, quantity of aggregate, and quantity of hardening agent, we can control the strength of the artificial foundation, even though the strength of the original foundation varies between soft clay equivalent and hard gravel equivalent.
Advansoil method (Fluidization and backfill process by mixing with demolished concrete)
The Georaft method (fluidization p ro c e s s i n g m e t h o d ) i s a foundation method developed as an a l ternat ive to rubble concrete of structural founda-tions. This new building founda-tion method is environment-friendly since it uses soils gener-ated by the other construction work to form highly rel iable solidified foundation.
08
We Provide Various Methods to Satisfy Any Ground-Related Requirements.
densification (non-liquefiable)
PROP(high-strength, deep mixing method)
HCP method (Hardening Compaction Pile; static concrete compaction pile method)
sand pile
settlement prevention
concrete pile
liquefiable layer
medium layer
bearing layer
Ground Improvement by Fudo Tetra
A hybrid (triple-layer) vibration-isolation wall method that uses gas cushions can be expected to provide vibration-isolation effects equal to that of a vibration isolation trench for a low frequency range (10 Hz or lower) of vibration and this vibration-isolation wall provides long-lasting func-tion. The vibration-isolation walls are composed of steel sheet piles, soil cement walls, and gas cushions. Gas Cushion is a vibration-isolation material that was
devised by Dr. K. Rainer Massarsch in the 1980’ s and has several examples of application in Europe.
This equipment can be used for both sand compaction pile method and deep mixing method through replacement of the attachments. Since this equipment has ultracompact dimen-sions, approximately one-fourth of that of conventional equip-ment, it realizes ground improvement work in narrow areas where such ground improvement work was infeasible in the past. This equipment is also easy to assemble and disassemble. Inclined work is available by using this equipment as well.
09 10
Closed System Triner method V-mixing method
Soil generated from construction site is effectively used as an alternative for natural sand. On-site processing of soils is feasible, and soils generated by excavation work can be reused.
Multi-type Ultracompact Construction Equipment
HGC method (Hybrid vibration-isolation wall using Gas Cushions)
A method used to build highly reliable water cutoff walls by combining soil cement walls and water cutoff plates made of sheets. Highly dense polyethylene sheets and special lightweight steel sheet piles can be selected as the sheets, de-pending on the purpose or ground conditions.
Surface treatment using trencher-type vertical mixing equipment, and its base with self-propelling rails in the horizontal direction, are combined to realize reliable mixing and acceler-ated construction work.
Fudo Tetra Cherishes Limited Resources by Effectively Utilizing Construction Materials and Construction Byproducts.
Fudo Tetra Creates Hybrid Technologies by Combining Conventional Technologies Each Other and Through the Adoption of Newly Developed Construction Equipment.
In addition, cost for the transportation of sand has to be counted, and collection and transportation of sand impacts on the surrounding environment.
Resoil method
Recycled materials
A new material made of steel slag, which is controllable in strength and expansion rates, is used as infilling material for sand compac-tion pile methods.
Ecogaia Stone
Scrap concrete and other materials gener-ated by demolition work are recycled on-site as infilling materials for Compozer or other ground improvement methods, or fluidized backfilling materials by mixing with special reagents.
Total recycling system
Sand has to be ordinarily purchased.
Cost for the transportation has to be counted, and associated impacts on the surrounding environment have to be considered.
Excavated soil is ordinarily carried out to a disposal area.
Reused as infilling materialsPre-treatment of the material is performed if necessary.
Closed system realized by utilizing materials generated by the other construction work within the same site
Reused as infilling material for SAVE Compozer, etc.
Manufacturing Delivery Placement
Recycled material
Fine granularization
Granularization
Reuse of construction waste materials
Hardening reagent
Mixing Loading Placement
Reused as fluidized backfilling material
NETIS Registration HKK-07001-ACertificate No. 10001, Coastal Development Institute of Technology
Triner methodWater cutoff wall with a three-layer structure
Conceptual diagram of Triner method
Contaminant
Aquiclude
Hybrid (triple structure) vibration-blocking w
all
Gas cushions
Gas cushions
Steel sheet piles
Steel sheet p
iles
Soil cement walls
Soil cem
ent walls
Gas cushion
Ground Improvement by Fudo Tetra
11 12
List of Available Technologies
Applicable or effective Applicable or effective depending on conditions
Protecting
Ground improvement method NETIS Registration Page
Retaining Supporting Weight reducing
ContainmentSubsidenceprevention
Liquefactionprevention
Landslideprevention
Earthretaining
Watercutoff
Excavationstabilization
Increase inbearing capacity
Increase in horizontalresistance of piles
Loadreduction
Void filling Soilremediation
SAVE Compozer
SAVE Marine method
Compozer
Resoil Compozer
Non-flow Compozer
Sand Drain method
Auger-type Sand Drain method
CF Drain method
Resoil Drain method
Packdrain method
Plastic Board Drain method
CS Drain method
Vacuum Consolidated Drain method
Fiber Drain method
PDF method
SAVE-SP method
Vibro-rod method
Mammoth Vibro-tamper method
Compaction Grouting Denver System
CI-CMC method
CMC method
MT-CMC method
CDM-LODIC method
TOFT method
PROP
DJM method
ALiCC method
HCP method
GCCP method
JACMAN
PJ method
FTJ method
X-jet method
Superjet method
Consolider method
V-mixing method
Power Blender method
Barge Consolider system
Permeating Solidification method
TRD method
Sheet Wall method
Geolock method
Triner method
LSS method
Georaft method
Advansoil method
High-grade Soil
FCB method
SGM Lightweight Soil method
Gravel Drain method
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static sand compaction pile method
Non-vibrating low-noise type offshore Compozer
Re-driving type sand compaction pile method
Compozer utilizing construction-generated soil
Large-diameter gravel compaction pile method
Partially-covered Sand Drain method
Drain method utilizing construction-generated soil
Bagged Sand Drain method
Plastic Drain method management system
Plastic Board Drain method
Natural Fiber Drain method
Floating type Plastic Board Drain method
Static ground compaction by sand injection
Vibrating rod method
Surface layer compaction method
Static compaction method by grouting
Large-diameter and superior quality deep mixing method
Cement deep mixing (CDM) method
Compact single-axis deep mixing method
Displacement-reduction-type deep mixing method
Aseismatic solidification method
High-strength deep mixing method
Powder discharge mixing method
Low improvement rate cement column method
Hardening Compaction Pile
Gravel cement compaction pile method
Cross-jetting-type composite mixing method
Cross-jetting-type composite mixing method by using compact equipment
Dual-flow cement slurry jet mixing method
High-pressure jet mixing method (cross jetting method)
High-pressure jet mixing method (large-diameter type)
Surface layer solidification method
Surface layer solidification method (by horizontally self-propelling trencher)
Shallow and intermediate layer mixing method
Pre-mixing method
Continuous soil cement diaphragm wall method
Special lightweight steel sheet pile water cutoff method
Vertical sheet method
Triple-layer structured water cutoff wall method
Fluidized soil placement method
Fluidization and backfilling processing of excavated soil with high strength and superior quality
Fluidization and backfilling processing by mixing with demolished concrete
Recycled soil by mixing with reinforcements
Air bubble incorporated soil
Air bubble incorporated soil
Gravel-piling method
CB-980039-V
HK-060002-A
CG-990065-A
KTK-040002-A
SKK-090002-V
QS-980018-V
TH-980041-V
KT-990165-A
HR-030032-A
KT-070009-A
HK-040022-A
QS-980153-A
CB-0500051-A
QS-040034-A
KT-990495-A
KK-980026-A
CB-980012-V
KT-990230-A
KT-980493-A
KT-990318-A
KT-980624-V
CBK-050002-A
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SMALLJUDGE
Available equipment specialized for offshore work
Compatible with offshore work
Low vibration & low noise
Use of recycled materials is available
Work on mud is available
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Applicable for countermeasures against soil and groundwater contamination
Equipment for work at narrow space and low height is available
Technical certificates by official statutory organizations are awarded
Mechanical mixing
With compaction
Jet mixing
Surface layer mixing
Premixing
Composite mixing
Grouting solidificationContinuous diaphragm wall
Consolidation, drainage, and compaction
Consolidation acceleration
Compaction
Water cutoff
Drainage
Lightweight
soil
Solidification
SAVE Compozer (Silent, Advanced, Vibration-Erasing Compozer)Static sand compaction pile method
The SAVE Compozer inserts and extracts casing pipes from the ground surface by the forced rotary press method (wave method), utilizing forced penetration and withdrawal equipment with new structural configurations. A casing pipe is first inserted to a prescribed depth before the wave processing is per-formed in short increments to increase the diameter of the pile and to compact the surrounding area. Quiet compaction is pos-sible, since no vibrational energy is used.
This method utilizes soil generated by construction work as an alternative material for natural sand which is the conventional ground improvement material. The same level of improvement as in conventional method is attained by inserting soil generated by construction work with artificial drain materials into the ground. It is a ground improvement method with consideration for the environment, offering both the conservation of natural resources and a solution for problems relating to the disposal of soil generated by construction work.
Compozer is a representative method of the sand com-paction pile methods in use. A vibrating casing pipe is penetrated into and pulled out of the ground repeat-edly, known as the "re-driving type method," in order to perform ground improvement by establishing well-compacted sand piles with large diameter to stabilize the ground. This method, developed and familiarized by Fudo Tetra, has been adopted worldwide, with a total completed pile length of 320,000 km.
The Vibro-rod method is used to compact loose sandy ground by inserting a variety of special rods that are penetrated by means of vibration. These rods have charac-teristic tips and side shapes.
This Compozer provides significant effects for the enhancement of bearing strength of the foundation ground and the reduction in sub-sidence by means of creating large diameter piles with tightly packed gravels or crushed stones. In this method, we adopt casing drill-ing throughout the entire depth and leave the casing during subsequent creation of gravel pile in order to reduce the impact on the surrounding structures and ground.
This method is used to create compacted sand piles without vibration and with low noise, as it uses non-vibrational forced penetration and withdrawal equipment and rotary equipment. This method is suitable for the waterside work such as reinforce-ment of a foundation for seawalls.
It can be used to carry out construction work at locations in the vicinity of existing structures, since this method has minimal impact on the surrounding environment because it involves no vibration and has a low noise level.It delivers the same improvement effect as the conventional sand compaction pile method.A new construction management system (CONOS) is used to manage the construction work The CONOS system is a highly reliable construction work management system that provides specific instruc-tions to the operator, thereby ensuring proper sand compaction pile installation.It can be applied not only to sandy soils but also to cohesive soils and other types of soils. We can use various materials other than sand, such as gravel or slag. Furthermore, a composite pile which has both sand drain part and sand compac-tion pile part is installable, since the pile diameter can be easily changed with the same equipment. Construction costs are more economical in compari-son with other environment-friendly ground improve-ment methods.
Features of the SAVE Compozer
Features of Compozer
Resoil CompozerCompozer utilizing construction-generated soil
The Compaction Grouting Denver System is a static compaction method by grout-ing that injects mortar with extremely low fluidity (5 cm or less of slump) into the ground without application of any vibration or impact at all. This system proves to be significantly effective for use beneath or adjacent to the facilities that are currently in service or at narrow areas where other methods cannot be implemented.
Vibro-rod methodVibrating rod method
Compaction Grouting Denver SystemStatic compaction method
The Mammoth Vib ro- tamper me thod i s used to compac t ground surface layer by combining strong vibrator and a large-scale tamper. A 4 m2-type tamper and a 9 m2-type tamper are available and selection will be done depending on the purpose of application.
Mammoth Vibro-tamper methodSurface layer compaction method
Non-flow CompozerLarge-diameter gravel compaction pile method
SAVE Marine methodNon-vibrating, low-noise-type offshore Compozer
Compaction
Trajectory of casing pipe tip
(Positioning) (Penetration completed) (Pile formation completed)
Locationing Penetration Pile formation
Sand
CompletionPenetration of rod Compaction
LocationingCompaction Locationing Compaction
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Artificial drain materials (plastic board drain, etc.)
Construction-generated soil, etc.
Fc: Fine grain inclusion rate Construction-work-generated soil, etc.
Artificial drain materials
CompozerRe-driving type sand compaction pile method
SAVE-SP methodStatic ground compaction by sand injection
Compact the target ground by pumping and injecting fluidized sand into the ground through ultra-compact equipment. The pumpable sand by mixing with fluidizing reagent is forcibly ejected from tip of a rod that was penetrated into ground and densifies the surrounding ground. Fluidity of the ejected sand is
gradually disappeared by dehydration and effect of added retarding plasticizer, and dense ground is formed.
Improvement of existing jetty foundation
Improvement of subgrade at airport runway, etc
Vibrating equipment
CB-980039-VCandidate for recommendable technology in 2008
Vibration level(dB)
Distance from operating equipment(m)
Distance from operating equipment(m)
Noise level(dB)
Consolidation, Drainage, and Compaction
Wide range of applicable groundWide range of applicable purposesAssured creation of Compozer pilesHighly reliable construction management and quality controlHaving most experiences for countermeasures against liquefactionVery deep underwater work or subsurface work is feasibleEconomical methodSuperior versatilityMakes reuse of construction byproducts possible
Vibration standard value: 75dB (standard value for construction workplace vibration)
With the SAVE Compozer, vibrations cannot be felt even in close proximity to the construction equipment.Novibration
With the SAVE Compozer, conversations at a normal voice level can be carried out ten meters away from the construction equipment.Low noise level
Vibration level
Hardlysensible
Sensible
Barelysensible
SAVE Compozer
SAVE Compozer
Conventional-type Compozer
Conventional-type Compozer
Background vibration
Noise level
Close to passing train
Inside subway car
Inside bus
Noisy office
Normal conversation
Quiet location
Noise level standard value: 85dB (Noise Control Law)
Background noise
SAVE Compozer
Forced penetration and withdrawal equipment
Rotary drive equipment
Casing pipe
(Positioning)(Penetration completed)
(Pile formation completed)
Locationing Penetration Pile formationForced penetration and withdrawal equipment Sand filling
Motor
Casing pipe
Wave-shaped succession of withdrawal/re-driving
SEA R SMALLJUDGE R JUDGE
Primary (secondary) construction-work-generated soilPile arrangement example
Artificial drain materials are not necessary for compacting sandy ground.
700 mm dia.
Fc<=25%
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Special metal
Installation completed
The Sand Drain method is one of the most representative vertical drain methods and has a long history of use in Japan. By using this method, we create vertical sand piles in soft ground to consolidate and strengthen the ground by utilizing their draining effects and also the load of the piles.The construction work management system is used to ensure the certain formation of the drain piles, since continuity of the piles is an essential factor for this method.
This is a method aimed at economical work by using the advantages of Packdrain method and Sand Drain method, while covering only essential portions with meshed tubes. Continuity in load transfer during and after implementation of the work is maintained, and drain effect for consolidation of the surrounding ground are sustained throughout.
This method utilizes construction-generated soil as alternative material for natural sand which is the conventional material used. This method can be used to obtain the same level of improvement as conventional methods, since draining effect is obtained through artificial draining materials and bags attached by the artificial materials. Further-more, this method is an environment-friendly ground improvement method that is economi-cally superior, with consideration for natural resources and solution of problems relating to the disposal of construction-generated soil.
This is the method used for ultrasoft ground or soft ground under shallow water, and is per-formed by constructing a plastic drain directly from a special floating equipment. Sand mats that are required for conventional methods are not necessary because special plastic materials are used as a horizontal drain layer.
This method is considerate of the environ-ment, using natural fiber for drain materi-als. Once these materials have fulfilled their role as drain materials, they decom-pose and assimilate with the soil.
In principle, this method is the same as the sand drain method, except plastic ma-terials are used as the drain materials. Since the materials used are industrial products, quality of the materials is con-sistent, lightweight, easy to handle, and they offers superior workability.
The Vacuum Consolidated Drain method puts negative pressure on soft layer for consolidation by utilizing the upper clay layer as a diaphragm to the negative pressure. A drain equipped with a sealing cap and a drainage hose on top of it is installed to the prescribed depth through clay layer and the target layer is drained and consolidated by the vacuum effect together with the vacuum- sealing function of the upper clay layer.
This system is capable of accurately detecting the imple-mentation status of work (co-withdrawal of drain material during withdrawal of drain installation pipe, and fracture in the drain material, etc.) of plastic drains, which is difficult to detect from the ground surface, thereby realizing supe-rior quality in the management of the implementation.
The PDF method makes it possible to drive vertical drains on the water or on the mud by using coupled floats. Further-more, a pre-solidification of ground surface or placement of sand mats is not necessary to secure trafficability when performing work on the mud. Combination with horizontal drains can also be used instead of sand mats.
To create secure sand piles in the ground, bags made of flexible synthetic fiber are used for the drain materials to be infilled in order to maintain the continuity of sand piles during and after implementation of the work. Multiple sand piles (two or four) can be constructed simultaneously.
This is the Sand Drain method by using electrical motor to penetrate casing pipes by rotation into the ground. There is less vibration and noise during the performance of this method and creation of sand piles without deteriorating the strength or per-meability is achievable without affecting any neighboring structures.
Features of Sand Drain method
Features of the PDF method
Comparison with conventional vacuum consolidation method
Vibrator
Sand
Completion of drain pile formation
Fc: Fines Content
Secondary, tertiary (and quaternary) construction-generated soil
Fc>25% Construction-generated soil, etc.
Construction-generated soil, etc.
Artificial drain materials
Artificial drain materials
Bags filled with artificial drain materials
Bags attached by artificial drain materials
1,700
500mm dia.
Features of CF Drain method
Sand
Sand
Fill (clay) Covered drain
Alluvial clay Sand Drain
Meshed tube set
Positioning, Sand infilling
Penetration, Sand infilling
Installation of drain pile
90mm
<Combination with horizontal drains>
Vertical drain
Soft ground
Pore water
Intermediate sand layer
Below water surface
Ground surface is sand layer
Water cutoff seal
This method can be applicable to the following situations, which has been considered difficult to deal with by using a convent ional method, since this method does not require any sealing sheets.
Consolidation of ground with a sand layer on the ground surfaceConsolidation of ground located below the water surfaceConsolidation of ground with an intermediate sand layer
Appearance of materials
Cross section of fiber drain
Palm tree bark rope: 5mm dia./piece
Outside hemp cloth Inside hemp cloth
9mm
Seam
Sand Drain method
CF Drain method (Complexed Flexible Drain)Partially packed Sand Drain method
PDF method (Plastic board Drain by Floating system)Floating-type plastic board drain method
Vacuum Consolidated Drain methodPlastic board drain method
CS Drain method (Control System for Prefabricated Drain)Plastic drain method management system
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Auger-type Sand Drain method
Resoil Drain methodDrain method utilizing construction-generated soil
Fiber Drain methodNatural fiber drain method
Plastic Board Drain methodPackdrain methodBagged sand drain method
Features of PDF method
Horizontal drains
KTK-040002-A CG-990065-A
HK-060002-A
Numerous performance recordsThis is the representative of the vertical drain methods and it has been in use of a variety of applications.Suitable for a wide range of applications for both onshore and offshore work This is the method with the longest history of both onshore and offshore work. Construction work can be implemented at deep underwater or deep subsurface conditions. Precise construction work management The construction work management system is used to monitor the construction work, such as the volume of sand filled, the penetration depth of the casing pipes, and the movements of the surface of sand inside the pipes during the withdrawal of casing pipes.
Applicability This sand drain method can be applied even to ultrasoft ground that cannot sustain the continuity of sand piles by conventional method.Construction work management Monitoring of the depth to which casing pipes are driven, movements of sand surface level inside the pipes, and status of the meshed tubes that remain in the ground, is possible by using the construction work manage-ment gauging system (depth gauge, sand surface gauge, etc.). Economical efficiency This is an economical method, since covering can be implemented at an arbitrary depth in the ground and to only the necessary portions.
Consolidation Acceleration
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Materials
Pile arrangement example
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Time required for completing the work can be shortened. Sand mats will no longer be required. Work can be performed on lakes and swamps. Capacity of dredged soil for disposal to this landfill site can be increased. GPS is adopted for the positioning. No vibration and low noise Environment-friendly method
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Features of CI-CMC method
CMC methodCement Deep Mixing (CDM) method
The CI-CMC method is a deep mixing method for creating larger diameter and higher quality improvement areas. These advantages are realized through the development of an “ejector discharge” mechanism that discharges atomized slurry with compressed air. Displacement of the surrounding ground during the mixing can be greatly reduced and this advantage makes this method suitable for the application at urban areas and in the vicinity of existing struc-tures. The CI-CMC method realizes reduction of construction costs by means of high produc-tivity without sacrificing superior quality.
The Clay Mixing Consolidation method (CMC method) is the most representative deep mixing method that uses chemical binding effects by mixing improvement mater ia ls such as cement s lurry and cement mortar with soft cohesive soil in situ for the purpose of improving the ground. This method is widely used at both onshore and offshore works.
This method is performed by the mixing shaft with spirals in order to remove the spoils equivalent in volume to the injected cement slurry during construction, and conse-quently reduce the displace-ment of the surrounding ground which usually occurs due to the injection of solidi-fying agents for the CMC method.
This method is intended to prevent lique-faction by confining the target soil through the creation of solidified walls in grid formations in the ground.
The ALiCC method is applied to reduce sub-sidence of the clayey ground due to consoli-dation which occurs directly underneath the embankment, by arranging the soil cement columns with larger spacing throughout the entire area directly underneath the embank-ment. Lower improvement ratio in compari-son with that of conventional methods can be applied, and cost reduction with shortening of construction schedule will be achievable.This highly reliable cement deep mixing
method enhances the bearing capacity of the ground that supports structures. This method creates improvement ground with high strength and little deviation in quality.
The DJM method (the Dry Jet Mixing method) is a deep mixing method intends to enhance the strength of the ground by discharging pulverized improvement materials such as lime and cement to soft ground and mixing them with the soil in situ. The characteristics of the improvement bodies are similar to those of the CMC method that uses slurry. This method was put into practical applica-tion based on the technology developed as a par t o f the "Research of New Ground Improvement Technologies" project by the Ministry of Construction (the Ministry of Land, Infrastructure and Transport in present). Stan-dard dimension of mixing blades are 1,000 mm in diameter and the blades with larger diameter of 1,300 mm are currently being developed.
Compact construction equipment
Variety of improvement sections
Ejector discharging system
1,000mm dia. 1,200mm dia. (standard)
1,600mm dia. (standard)
2,000mm dia.
Ap: 0.79m2
Ap: 4.02m2
1,000
1,00
0
1,200 1,600 2,000
2,00
0
1,60
0
1,20
0
Ap: 1.13m2 Ap: 2.01m2 Ap: 3.14m2
1,600
Tangent configuration Independent configuration Overlapped configuration
Max. 2,000
1,60
0
1,60
0
3,200
1,60
0
1,400
3,000Max. 3,600
1,600mm dia.Ap: 4.02m2
1,600mm dia.Ap: 3.91m2
1,600mm dia.
This system discharges atomized slurry with compressed air and mixes the ground with slurry more precisely and uniformly.
Ejectordischarging
systemReduced displacement of
surrounding ground
Improved mixing efficiency
Improved penetration capability
Reduction of costs
Higher quality & larger diameters
Higher construction productivity
Construction sequence
Spoil
Schematic diagram for structure of dry jet mixing blade
Improvement column
Improvement materials & air
Blowout prevention cover
Exhaust
Improvement materials & air
GCCPGravel cement compaction pile method
In GCCP method, we use gravel with cement as an infilling material instead of sand that is generally used in conventional Sand Compaction Pile method, and create gravel cement pile with higher strength. Different from Cement Deep Mixing method that strength is fluctuated due to the character-istics of treated soil such as content of organics, GCCP piles have consistent qual-ity with higher strength.
Positioning of equipment
Penetration
Bottom mixing
Discharging of improvement materials and mixing during withdrawal
Cleaning of mixing blades and relocation of equipment
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CI-CMC method (Contrivance Innovation Clay Mixing Consolidation)Large-diameter, superior quality deep mixing method
CDM-LODIC method (Cement Deep Mixing - LOw DIsplacement Control)Displacement-reduction-type cement deep mixing method
TOFT methodAseismatic solidification method
ALiCC method (Arch action Low improvement ratio Cement Column)Low improvement rate cement column method
PROPHigh-strength deep mixing method
DJM methodPowder discharge mixing method
Single axis construction work
Spoil is withdrawn in steps or
Load of embankment on improved columns
QS-980018-A
HK-040022-A
TH-980041-V
KT-990165-A
HR-030032-A ※HL-DJM method
KT-070009-A
Fill Fill
Cement Deep Mixing (DJM, etc.)
GCCPPeat layer
Cost reduction, Shortening of construction duration
Clay layer
〈 Cement Deep Mixing 〉Diameterφ1,000mm Improvement ratio αp=50%Hardening agent: Special cement (expensive)Dosage of cement: Peat→more Clay→less
〈 GCCP 〉Diameterφ700mmImprovement ratio αp=25%Hardening agent: Portland cement (inexpensive)Dosage of cement: less for both Peat and Clay
Solidification
Superior quality large-diameter piles Improvement of the mixing efficiency achieves creation of larger volume of improvement with maintaining extremely small deviations in its quality. Superior penetration capability Improvement of the penetration capability makes it possible to perform mixing even in a ground with a higher resistance against penetration. Lower displacement The air lifting effect contributes release of internal pressure and significantly reduces displacement of the surrounding ground.
Twin axes construction work
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Arching effect
By the installation of concrete piles into ground through SAVE Compozer procedure, densification of the surrounding ground is achieved to prevent l iquefaction of the ground during seismic event, while the installed concrete piles increase bearing capacity of the ground.
HCP methodHardening Compaction Pile; static concrete compaction pile method
densification (non-liquefiable)
sand pile
settlement prevention
concrete pile
liquefiable layer
medium layer
bearing layer
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JACSMAN (Jet And Churning System MANagement)Cross-jetting-type composite mixing method
TRD method (Trench cutting and Re-mixing Deep wall)Continuous soil cement diaphragm wall method
FTJ method (Fudo’s Twin Jet)Twin cement slurry jet mixing method
PJ method (Petit Jet)Cross-jetting-type composite mixing method by using compact equipment
X-jet methodHigh-pressure jet mixing method (cross jetting method)
Superjet methodHigh-pressure jet mixing method (large-diameter type)
Features of JACSMAN
This method has advantages of both the mechanical mixing method and the high-pressure jet mixing method. With this method it is possible to create soil cement mass that contains no untreated soil chunks. The TRD method is used to create a con-
tinuous wall in the ground. A chainsaw-shaped cutter is inserted into the ground and connected with a base machine. Then the cutter is moved laterally and a ditch is dug while the solidifying agent is injected and mixed with the soil in situ to create a wall in the ground.
The barge consolider system is used to create landfill material from dredged sedi-ments, by mixing them with cement slurry on the sediment transport vessel (barge) equipped with a blade-type vertical mixing equipment and a cement slurry plant.
The FTJ method is used to create improvement areas with large cross-section by jetting solidifying slurries from the tips of the mechanical mixing blades. Furthermore, high-speed work is achievable by the twin jetting of slurry and construction time can be shortened. This method can be widely applied, including tight bonding of two different structures such as between earth-retaining wall and ground improvement mass that was mechanically created and not tightly connected with the wall.
This deep mixing method combines mechanical mixing and jet mixing methods, making it easier to implement overlapped improve-ment and tightly connected improvement. A single piece of equip-ment can be used to both high-productivity work and overlapped work, by using two different types of mixing blades. By means of downsizing of the equipment and reduction in weight of the plant facilities, this method is suitable for performing ground improvement work in narrow spaces in urban areas.
This method offers soil cement columns with constant diameter and uniform quality that are considered difficult to achieve by using conventional jet grouting methods, since the boundary of the improvement area is con-trolled by crossing of ultrahigh-pressure jets.
Development of cross jetting method made it possible to control the boundary of improvement that is infea-sible by using conventional high-pressure jet mixing methods. This advantage makes the following possible:
Composite mixing offers the following advantages over conventional mechanical mixing methods:
Cross jetting Composite mixing
Type A
3,300
Type B
3,700
1,000
1,000
1,300
650 100 5002,300 2,300
1,400Improved area: Ap = 6.4m2 (Creation speed: 0.5m/minute or less) Improved area: Ap = 7.2m2 (Creation speed: 1.0m/minute or less)
Power Blender methodShallow and intermediate layer mixing method
Barge Consolider systemPremixing process method
Th is method uses a base mach ine equipped with a trencher-type mixing blades to mix improvement materials, such as cement or solidifying agents, into a slurry form, with soft soil in situ to solidify them.
Consolider methodSurface layer solidification method
This method is used to enhance the strength of soft ground by solidifying its surface to get enough trafficability.
The Permeating Solidification method has been made through the modification of the conventional double-tube, double-packer method to permeate loose sandy ground with special silica. Narrow tubes are used with compact equipment and highly perme-able permanent chemicals are injected only to the limited locations where countermea-sures against liquefaction are required. Because of these features, the impact of the injection on structures is small, thereby injection work adjacent to existing facilities is possible and totally economical work is achievable.
Permeating Solidification method
Foundation mullocks
Backfilling stones
Infilling sand
Infilling sand
Infilling sand
Caisson
Pre-treatment injection
Crushed rock layer
Diameter of the improvement area is accurately controlled, without being influenced by the ground conditions. Compressive strength of improvement mass can be freely adjustable within the range between 0.2 and 1.0 MN/m2. Since significant improvement in mixing performance has been achieved, highly eff icient production is possible without sacrificing the uniformity of improve-ment mass.
Trajectory of JACSMAN blade
Trajectory of JACSMAN blade
This ground improvement method creates soil cement columns with larger diameter by jetting solidifying agents into the ground with ultrahigh-pressure and large flow rate. High-speed construction efficiency, ten times faster than the conventional methods, is realized.
Cutter post
V-mixing methodSurface layer solidification method (by horizontally self-propelling trencher)
This solidification method that improves ultrasoft ground is developed through a review of the conventional method that is used to perform a solidification process by moving horizontal mixing blades vertically and laterally. With this method, a trencher-type vertical mixing equipment is mounted on the floating platform vessel, and the vessel moves laterally with the mixing equipment being inserted into the ground and mix the ground with hardening agent.
Permeated solidification
QS-980153-A
QS-040034-A
CB-0500051-A
KK-980026-A
KT-990495-A
CB-980012-V
KT-980493-A
KT-990230-A
Solidification
Tight connection with the existing structures or the adjacent improvement mass can be performed accurately and easily. Improvement mass with large cross-sectional area (four times larger than the conventional mass) can be created. Diameter of improvement mass can be changed at any arbitrary depth by stopping the cross jetting.
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Bearing stratumBearing stratumBearing stratum
GeoraftGeoraftGeoraft
GeoraftGeoraft Georaft
The Triner method is a vertical water cutoff wall to prevent seepage of contaminants into the surrounding ground or groundwater by confining the contaminated soil inside the wall. The Triner method is a highly reliable water cutoff wall method that combines two often used con-ventional methods, continuous diaphragm wall water cutoff (soil cement walls) and water cutoff sheet (water cutoff plate), and advantages of these two methods are obtainable.
The Georaft method (fluidization processing method) is a foundation method developed as an alternative method to the rubble concrete of structural foundations. This new building foundation method which makes highly reliable solidified foundation consists of the soils generated by the other construction work is environment-friendly. This concept of reuse of construction generated soils depends on the "Law for Promoting the Use of Regener-ated Resources" (abridged version). Further-more, this method is used not only for build-ing foundations but also as an earth-retaining method and other backfilling procedures.
High-grade Soil is a construction material made of construction-generated soil with added value to make it compatible with sophisticated and multifaceted require-ments. Four methods are applicable: the Air Bubble Composite Soil method, Foam Bead method, Bagged Drain method, and Synthetic Composite Soil method.
The Gravel Drain method prevents liquefac-tion by inhibiting the rise of pore water pressure during earthquakes by shortening the horizontal draining distance through installation of piles made of crushed stones in sandy ground.
The Geolock method is a water cutoff method that uses highly dense polyethylene sheets. This method is optimally suited as a water cutoff at waste disposal plants, since the material used has superior chemical resistance characteristics.
The Sheet Wall method is a water cutoff method, which creates continuous walls in the ground by using thin plates (sheet walls) with coupling functions.
The weight and strength can be adjusted easily by changing the mixing proportion of cement, soil, water, and air bubbles. Con-struction byproducts, such as soil or clay generated at construction sites can be used, as well as ash and sludge.
The LSS method that has highly f lu idized material shows satisfy-ing results at backfilling o r bank ing work in areas where compac-tion after the place-ment of the material is difficult or unexposed areas such as under floors. Various types of soil generated by construction work can be used as the regenerated resources.
Soft ground
Chemically stabilityDynamic rigidityUniform water cutoff
Solidified wall construction equipment
Sheet-driving equipment
Aquiclude
Triner methodWater cutoff wall with a three-layer structure
Contaminant
Water cutoff plate
Soil cement wall
Three-layer structured wall
Sheet (main body)
1,350(effective width) 200
A A’
200
800
2
A-A’
Sealing material (5.7mm dia.)
(Welding)(Welding)
Locking section (male component)
Locking section (female component)
Effective length (determined based on the depth to which sheets are driven)
Lower section for clamping when setting the sheet on sheet-driving equipment
Top section for clamping when setting the sheet on sheet-driving equipment
Features of Sheet Wall method
Cross section
1,000mm
Impermeable grout material
Bridge Air bubble incorporated lightweight soil
PavingAbutment Fill
Foundation pile
Drain creation completedPositioningPenetration, Materials inserted
Verifying depth of leading tip
Withdrawal Drain creation
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Triner methodTriple-layer structured water-cutoff wall method
High-grade SoilRecycled soil by mixing with reinforcements
This is a new foundation method that utilizes demolished concrete as an aggre-gate of fluidized backfill processing mate-rial for the building foundation.By adjusting specific gravity of fluidized mud, quantity of aggregate, and quantity of hardening agent, we can control the strength of the artificial foundation, even though the strength of the original founda-tion varies between soft clay equivalent and hard gravel equivalent.
Advansoil methodFluidization and backfill process by mixing with demolished concrete
This is the regenerated soil by adding and mixing with solidifying agents, such as cement and air bubbles, to the cohesive construction-generated soil. The soil is used as land filling and backfilling material for creating stable and lightweight ground in harbor, port, and sea environments.
SGM Lightweight Soil method (Super Geo-Material)Air bubble incorporated soil
The EPS method is the banking method that uses large blocks of Styrofoam as banking materials and piling and unifying them. By using this new method, we can create stabilized ground with ultralight-weight, compression resistant, water resis-tant, and self-standing characteristics when piled up.
EPS method (Expanded Poly-Styrol)Banking method by using foam polystyrene
Geolock methodVertical sheet method
Sheet Wall methodSpecial lightweight steel sheet pile water cutoff method
Georaft methodFluidization and backfilling processing of excavated soil with high strength and superior quality
Gravel Drain methodGravel piling method
LSS methodLiquefied-Soil placement Stabilization method
FCB method (Foamed Cement Banking)Air bubble incorporated soil
Features of Gravel Drain method
KT-990318-A
KT-980624-V
KT-980397-V
CBK-050002-A
Water cutoff DrainageLightweight soil
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Secured water cutoff effectsWater cutoff effects are secured by using sheet walls with a large width (one meter by the stan-dard) and injection of impermeable grout mate-rial to the couplings.Cost effectivenessSince thickness of the sheet walls is thinner (2.7 to 4.5 mm by the standard) than the conven-tional sheets, this method needs less material and cost effective.Easy installationInstallation can be implemented accurately and rapidly by using specialized frames for the sheet driving. Furthermore, installation can be carried out even in the layer with gravel. Since the driving direction can be changed at the coupling sections, the water cutoff wall base lines can be adjustable to meet the required conditions.
Low levels of vibration and noise This method is applicable for the countermea-sures against liquefaction in urban areas. Availability in the vicinity of existing structures Since ground deformation caused by the imple-mentation of work is extremely small, there is no impact on the existing structures in the vicinity.Superior quality A dense gravel drain is created by using a special vibrating probe mounted at the tip of the casing pipe.
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Constructionachievements
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Haneda airport shoulders Japanese skyways. Fudo Tetra has been proposing and being adopted various on-shore and off-shore ground improvement methods such as Com-pozer, Sand Drain, CF Drain, and CMC for the extension projects of this airport since their first phase in 1984.At construction of East Side Terminal Building, Compozer has been adopted as a counter-measure against liquefaction of the ground at apron area, while CMC and JACSMAN have been adopted for the stabilization of excava-tion bottom and excavated slope to realize one-time excavation at building construction work.At present, the fourth runway (D runway) and international flight area are under construction. Off-shore Compozer is adopted for the stabili-zation of reclaimed foundation for seawall at runway area and SAVE Compozer is adopted as a countermeasure against liquefaction of the ground at international flight area.
Tokyo International Airport (Haneda)
This is the refurbishing work performed at the Chiba Thermal Power Plant, the oldest power plant of the Tokyo Electric Power Company and whose operation began in 1957. Thirty five (35) sets of construction equipments were fully operat-ing during the peak period and 486,000 meters of Composer and 249,000 meters of Sand Drain were constructed in a half-year period.
Tokyo Electric Power Company’ s Chiba Thermal Power Plant
Urawa-Misono Train Depot of the Saitama Railway Company
A practical foundation method that satisfies both securing bearing capacity and countermeasure against liquefaction which occurs at ground during earthquakes is realized by arranging high-strength PROP columns in a grid formation with the TOFT method at the Sakata site and the Tsuruoka site of the Tohoku University of Community Service and Science located in Sakata City and Tsuruoka City in Yamagata Prefecture. The work involved the construction of two-axis columns with a diameter of one meter, over-lapped by 20 centimeters to form a cross-sectional improvement area of 1.5 square meters throughout the liquefaction zone. The maximum length of the columns is 12 meters with a total of 2,651 sets.
Tohoku University of Community Services and Science
The Saitama Railway Line is a subway system designed to increase the capacity of transportation in the area between the JR Keihin Tohoku Line and Tobu Isesaki Line for the residents’ convenience. A total length of 137,136 meters of Sand Drain was constructed at the Urawa-Misono Train Depot (approximately 65,000 square meters) located closest to Saitama Stadium as a countermeasure against consolidation settlement, while 5,769 cubic meters of JACSMAN was constructed to improve the bottom of the excavated portions and to tightly connect the bottom improvement with diaphragm walls in the runway of the subway that links up with the train depot.
[Design administrator : Nihon Sekkei, Inc.]
Ground Improvement by Fudo Tetra
Constructionachievements
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The Osanbashi Jetty, fulfilling the role as the marine gateway to Yokohama since its opening in 1894, has been reborn as a new pas-senger ship terminal. JACSMAN and CDM-LODIC work were performed for the construction of the new terminal to reinforce the ground behind the quay walls.
International Passenger Ship Terminal of Yokohama Osanbashi (Jetty)
The Composer, Sand Drain, and Pack Drain methods were imple-mented in order to obtain rapid stabilization, prevent subsidence after completion, and prevent liquefaction on the plant site that was approximately 300,000 square meters. The surface layer solidifica-tion process and sheet netting methods were implemented to secure trafficability for the ground improvement equipments and install temporary roads on the landfill area in its early ages. Further-more, Tokoname clay was effectively reused as banking material.
Toho Gas Company’ s Chita-Midorihama Plant
The Coastal Subcenter of Tokyo is built on the 448 hectares of landfill that is located approximately in the middle of Tokyo Bay and is protected by various ground improve-ment technologies. The Sand Drain method was adopted as prevention of ground sub-sidence, while Compozer and SAVE Compozer were adopted as countermeasure against the liquefaction of the ground beneath major facilities. The CMC method was adopted to stabilize earth-retaining walls for excavation and as a countermeasure against liquefaction for the construction of common utility ducts.
The Coastal Subcenter of Tokyo (Tokyo Rinkai Fukutoshin)
Recovery work by employing deep mixing methods such as CMC, CDM-LODIC, and DJM was conducted to repair levees in the Torishima district that had serious damage due to the Hyogo-Ken Nambu Earthquake in 1995. The function of these levees was restored in a short period of time.
Disaster Recovery Work at Torishima in Yodo River
Ground Improvement by Fudo Tetra
