Soil improvement works

• Plastic Board Draining Method
• Sand Drain Operation System
• DECOM <Features of DECOM /CDM SYSTEM>
• Balloon Grouting Method
• Spiral Drain Method

The Plastic Board Draining Method is a method used to improve soft clayey foundations by accelerating dehydration and consolidation through the use of plastic boards installed into the ground. Surcharge loads are applied, generating excess pore water which is then drained through the boards, resulting in a drier, firmer and more stable foundation.

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The Sand Drain Operation System is a soil improvement method that works by installing sand columns into soft ground at desired locations. The technique involves driving closed-bottom casings into the sub soil using either Static Driving or Dynamic Driving according to soil conditions. When the casings reach the required depth, they are then filled with sand. The bottom of casings are then opened and the casings withdrawn leaving sand columns.

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DECOM (Deep Cement Continuous Cement Deep Mixing Method) is a method for hardening soft foundations by mixing sub-soil with stabilization agents such as cement slurry. A rotatable mixing shaft withblades is inserted to the required depth in the soil to be stabilised. The stabilization agent is then injected and mixed in-situ with the sub-soil. During this operation, the mixing shaft is gradually withdrawn thus forming hardened columns within the sub-soil.

The method is suitable for both onshore and offshore works and for various purposes such as massive construction, narrow space construction and treatment of contaminated soil.

<Features of DECOM / CDM SYSTEM>

1. (1) Ensuring the required strength is achieved.
2. (2) Effective reduction of overall construction period
3. (3) Eliminates settlement
4. (4) Minimizes environmental impact
5. (5) Reduces the volume of sub-soil needing improvement.
6. (6) Achieves cost savings through efficient use of resources.

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The Balloon Grouting Method is a chemical grouting method used to avoid liquefaction underneath existing structures and leakage of back-fill material behind existing wharfs. This method uses low pressure-injected chemicals into boreholes (96mm diameter) to strengthen foundations.

This operation can be carried out without damaging existing facilities and disturbing their operational activities. As the equipment is relatively compact, this method is particularly useful where space is restricted.

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The Spiral Drain Method is a technique to prevent sandy grounds from liquefaction by the installation of special polyethylene cylindrical pipes. The vertical / inclined – installed pipes can drain excess pore water which occurs during earth quakes and can dissipate its pressure immediately.

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