HVDM is a soft soil treatment method that is fast and combines vacuum drainage and deep dynamic compaction in designated cycles, so that soils at the project site can be improved through the effects of lowered water content and increased density. By using this method, soil strength and stiffness are improved, and the total and differential settlements after HVDM treatment are minimized.
The development of HVDM can be traced back to early 2000, when the inventor, Mr. Shi-Long Xu of Shanghai Geoharbour Group, began experimenting with the concept of high vacuum densification and applying it in a large scale to many well-known projects around Shanghai, such as Shanghai Pudong Airport Runway No. 2, Shanghai International Circuit, and the Shanghai port expansion.
Mr. Xu later filed patent applications and received Patent Cooperation Treaty approval for several separate but related soft ground improvement technologies. Among the three main patents are patent no. ZL 01127046.2, involving the use of multiple cycles of high vacuum process and varied dynamic compaction efforts (or mechanical compaction) to reduce water content in soft soils; patent no. ZL 200410014257.9, involving the combined use of surcharge preloading or vacuum consolidation, followed by HVDM; patent no. ZL 200510134966.5, involving the use of HVDM followed by construction of stone columns or other types of composite foundations. After initial successful applications in the Shanghai area, HVDM was expanded into other areas in China and other countries in Asia, such as Vietnam, Malaysia, and Indonesia. Currently, HVDM has become a major method used in land reclamation projects along coastal areas in China, with over 9 million meters square of land treated in the last 7 to 8 years.
HVDM can be described as a fast ground improvement technology utilising drainage, consolidation, and densification principles. HVDM is generally executed in a controlled manner based on feedback of on-site monitoring data collected for quality assurance and quality control (QA/QC) purposes.
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