In order to understand the mechanical properties of the compaction results and to optimize the relevant energy design of the repeated Rapid Impact Compaction (RIC), a series of California Bearing Ratio (CBR) tests were performed on the compaction sample with RIC electro-mechanic system. In this laboratory test, samples were compacted at various RIC impact energy levels. A mass of different weight and various of falling height was used to compact the samples in a CBR cylindrical test. The mass was repeatedly dropped on the anvil plate with a frequency of 30-40 blows per minute. The compaction process carried out by varying number of blows from 5 to 35 for each compacted sample, and all compaction processes were controlled by electro-mechanic new development system. The test results represented that there was a variation of CBR value at the same RIC energy levels. The CBR values at the same energy level with the larger number of blow increased higher in lighter mass, whereas than the RIC energy level for larger masses with the smaller number of blows also occurred with the same trend to the result of relative compaction density test. This advantages that with a better understanding of RIC mechanisms and relevant energy designs, it is a new practical idea to improve compaction degree as well as CBR value on fill construction works with appropriate equipment and lower energy consumption.

Liquefaction process is associated with the loss of the shear strength of the saturated loose sands caused by strong earthquakes. Due to mitigitation of liquefaction hazard, an appropriate mitigation of liquefaction using environmentally friendly methods is critical and becoming increasingly important and unavoidable. The laboratory investigation was carried out to study the shear strength behaviour of liquefiable sand of Petobo treated by agarose on different concentration 1%,3% 5%. A series of direct shear test were conducted under three level of vertical stress 10 kPa, 20 kPa, and 30 kPa on the specimen. It was found that the optimum content of agarose which can be considered is at 1%-3%, using stress ratio (τ/σv) analysis shows that stress ratio decreases with increasing the vertical stress on the same agar content. The implication this result that the application of this method must consider variation of material source and characteristic, and the suitable level of vertical stresses.

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