Geotechnical design and analysis Subject:
Korean ground improvement
I am working on a project constructing 110 km highway. We have an area of week soil which need to be improved. In Vietnam we normaly use "sand pile" to drain. I have heard that Korean have new technology of making this small "sand pile " with diameter of about 180 mm but with "fabric cover" which claimed to protect this "sand pile" from broken. Anyone knows about this please help.
1)For a vertical drainage system it is possible to install geosynthetic vertical drains (to accellerate the consolidation). You can combine this drains with a load transfer platform using a geogrid reinforcement.
2) For a raft foundation of buildings and dams we are using soil stabilisation with vertical columns, too. The CSV-method (Combined Soil Stabilisation with Vertical Columns) was developed on the principles of ground improvement using lime columns. The method consists of driving a worm flight auger of about 10 cm diameter with a special drilling head into the ground to a maximum depth of about 12 to 20 m. The driving process leads to lateral displacement of the soil. At machine level, the worm flight auger passes through a funnel, where aggregate is added. On reaching final depth, the auger is withdrawn and aggregate is simultaneously pressed into the surrounding soil with a compacting effect. Thus, columns with a diameter of about 10 to 20 cm are produced. The resulting diameter depends on the strength characteristics of the surrounding soils and the production parameters. The CSV-method can be applied in soft cohesive soils and loose non-cohesive soils, which are statically displaceable. The method cannot be applied in soil strata including gravel and stone layers, as these cannot be displaced by the auger. The CSV-method can be applied where the ground water table lies near the ground surface. It has no vibration impacts on the surroundings. The aggregate used usually consists of a dry mixture of sand (grain size 0/4) and cement. The compaction effect on the surrounding soil gives rise to pore water pressures, which upon dissipation, lead to drainage of the soil. pH-variations according to the type of aggregate used may also lead to dewatering of particular clay mineral structures. After seven days, the columns reach a compressive strength of about 5 to 10 N/mm².