The permeability (k) of lime- and cement-treated clayey soils was investigated in the laboratory by flexible-wall permeability tests and oedometer tests. Test results indicate that for the cement-treated soils (with up to 8% cement content by dry weight), the value of k is almost equal to that of untreated soils under identical void ratio (e) conditions, and the k value decreases significantly when the cement content is higher than 8%. For lime-treated soils, the threshold lime content is about 4%. Investigation of the soil microstructure using the mercury intrusion porosimetry (MIP) test and scanning electron microscope (SEM) imaging indicates that when the cementation products formed by the pozzolanic reaction fill mainly the intra-aggregate pores, the value of k is comparable for the treated and untreated samples. When the cementation products begin to fill the interaggregate pores, the value of k of the treated sample becomes smaller than that of the untreated soil sample under the identical e value condition. An indication that the cementation products have filled the interaggregate pores is the rapid increase in strength of the treated soil.

Soil improvement by preloading with PVD in combination with vacuum is helpful when a considerable load is required to meet the desired rate of settlement in a relative short time. To facilitate the vacuum propagation, vertical drains are usually employed in conjunction. This ground improvement method is more and more applied in the Mekong delta of Vietnam to meet the needs of fast infrastructure development. This paper reports on a pilot test that was carried out to investigate the effect of ground improvement by vacuum and PVD on the rate of consolidation at the site of Saigon International Terminals Vietnam (SITV) in Ba Ria-Vung Tau Province, Viet Nam. Three main aspects of the test will be presented, and namely, instrumentation and field monitoring program, calculation of consolidation settlement and back-analysis of soil properties to see the difference before and after ground improvement.

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The Da River Basin is an international basin where available access to hydrological data is limited; it has a total basin area of 52,900 km 2 , about 50% of the area in which it is located, Vietnam. The Da River is the primary source of water for agriculture in 25 provinces and cities, and the primary source of drinking water for more than 30 million people in both urban and rural areas. It has huge economic and historical value. However, flood forecasting for the Da River basin has not been adequately addressed yet because of the challenge of the inconsistency, scarcity, poor spatial representation, as well as difficult access and incompleteness of the availability of ground observed rainfall data. In this research, the IFAS model has been utilized to assess the benefits of using satellite-based precipitation products to create flood forecasting for the whole research area. The results showed that the Integrated Flood Analysis System (IFAS) model was able to integrate the satellite-based precipitation products for simulating the flood event in the Da River basin. Also, the 3B42RT algorithm showed a definite improvement in reproducing the flood peak and low flow very well in the research area. These results could be used to enhance the effectiveness of flood management strategy in the basin.