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Abstract For the very soft dredger fill site，it seems very hard for workers and construction machine standing and moving on the ground surface. That site is intended to be in use for agriculture. To meet such a need，the ground improvement should be implemented. Due to lack of the resources of sands，the sand cushion commonly used in the conventional method is replaced by reeds acted as drains in the vacuum preloading tests. Comparisons between results of vacuum preloading tests with and without bedding layer are obtained. Due to different loading processes of vacuum preloading tests with and without bedding layer，effects of consolidations of foundation vary considerably. In the case with no reed bedding layer，the velocity of consolidation in early stage is faster with small foundation settlement and low time cost，but this velocity decreases faster with the reduction in the settlement of the ground. In another case with reed bedding layer，the velocity of consolidation in early stage is relatively slow with some decreasing rate. It lasts about 33 d to make the same settlement magnitude as the site with no the reed cushion，and makes more 10.4% of total settlement than with no the reed cushion at the end. Moreover，the bearing capacity is higher than without reed layer. It shows that vacuum preloading method with reed bedding layer is a better ground treatment method. It has greater effects，shorter construction period and lower cost. It could be widely spread in the future construction.
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Received: 04 November 2010
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2011, Vol. 30 
