Pneumatic
caisson
technology
Shield tunneling
technology
Port and
harbor technology
Urban rejuvenation
/green technology
Outline of pneumatic caisson
Mud pressurization (DK) shield method
Dolphin dock construction method
Reinforce and Repair by Compound Closingwall (RECC) construction method

Outline of pneumatic caisson

This construction method sinks caisson through excavation using air pressure.

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Outline of Pneumatic Caisson
Construction Method

The pneumatic caisson method builds caissons made of reinforced concrete having a workroom where excavation is conducted, eliminates groundwater by sending compressed air matching the groundwater pressure to the workroom in order to perform excavation/sinking constantly in a dry environment, and installs the structure at the predetermined location. This construction method is widely used for underground structures including foundation of bridge, shield work shafts, and the foundation of the dam.

Procedure of Pneumatic Caisson
Construction Method

As for the work procedure, construction, excavation, and sinking is repeatedly conducted for each lot, and after ground support is confirmed, hollow-filling concrete is charged in the workroom in a dry environment.

Technology and process
of pneumatic caisson
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Principle of Pneumatic
Caisson
Construction Method

The pneumatic caisson method is an application of the principle that a cup turned upside down can prevent entry of water due to air pressure when it is pushed into water in a flat state. In fact, an airtight workroom is built in the lower area of the caisson, and by sending compressed air into it, entry of groundwater is prevented, allowing for excavation in a dry state. The inside of the cup corresponds to the caisson workroom, and the tip of the cup corresponds to the blade tip of the caisson.

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Characteristics of Pneumatic
Caisson Construction Method

Bridge foundations and structures built using the pneumatic caisson method have many superior characteristics.

- Highly reliable as a structure

- Durable

- Applicable to various soil properties from soft ground to rocks

- Secure process management

- Existing structure/foundation or unexpected underground obstacles can be securely removed

- Less impact on the surrounding environment

- Suitable for neighboring work

- Economical in terms of total cost

Comparison of Pneumatic
Caisson Foundation and
Other Construction Methods

Construction
method
Construction
condition
 Pneumatic caisson Open caisson Steel pipe sheet pile
well		 Continuous under
ground
wall		 Ready-made pile Cast-in-place pile
Driving Pile press-fitting by inner excavation
Construction
depth		 5 to 15m img img img img img img img
15 to 25m img img img img img img img
25 to 40m img img img img img img img
40 to 50m img img img img img img img
50 to 60m img img img img img img img
60 to 70m img img img img img img img
Soil
quality		 Soft soil img img img img img img img
Hard soil img img img img img img img
Base/
cobblestone		 img img img img img img img
Rock img img img img img img img
Removal of
obstacles		 img img img img img img img
Check of
bearing layer		 img img img img img img img
Underground
water		 Pressurized groundwater img img img img img img img
Flowing groundwater (flowrate of approx. 3 m/min or higher) img img img img img img img
Reliability Resistance
against earthquake		 img img img img img img img
Durability img img img img img img img
Workability Work above water img img img img img img img
Space with
narrow work area		 img img img img img img img
Work under floor img img img img img img img
Environment Measures against noise/vibration img img img img img img img
Influence on
adjacent structures		 img img img img img img img
Utilization of underground space img img img img img img img

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