Sustainable soil improvement via vacuum preloading
The application of prefabricated vertical drains combined with vacuum and surcharge preloading is considered to be one of the most environmentally friendly ground improvement techniques. The natural atmospheric pressure is used to generate suction via a vacuum pump. In comparison with other ground improvement methods such as deep piling and deep mixing, this method will not only save a substantial cost in road and rail embankment maintenance and construction but will also enhance the speed of construction of coastal highways and rail tracks and their capacity to carry a greater traffic load. Moreover, as drains with vacuum pressure do not involve chemicals, the soil and groundwater chemistry will not change, unlike cement and lime treatment. Vacuum preloading will also reduce the impact on the environment by minimising the greenhouse gas emissions and the need for quarrying natural sand and gravel. The performances of three full-scale test embankments constructed in Thailand, China and Australia are discussed collectively, demonstrating the advantages and environmental benefits of vacuum consolidation in relation to a standard surcharge-only system.