Ground Improvement technique Dewatering Methods
- 1. Dewatering Methods Open sumps and ditches
- 2. Dewatering • If water is leaking into the trench during foundation excavation, it is very important to dispose of it. • If water is not removed from the trench, it is difficult to make concreting or masonry in the foundation • The action of removing water from the foundation is called dewatering.
- 3. Necessity of dewatering • Ease of concreting or masonry in foundation. • To prevent soil erosion around the base. • To protect concrete or masonry from the effects of water.
- 4. • The essential feature of this method is a sump below the ground level of the excavation at one or more corners. A small ditch is cut around the bottom of the excavation, falling towards the sump. • The ditches size is usually 20cm in diameter of a semicircle. • Sumps are made at a distance of 40m to 60m in the ditches. The size of the sumps is kept as 1m*1m*1m.
- 5. • The water flows into the ditches and collects in the sumps. • Water is pumped out from the sumps by the use of centrifugal pumps.
- 6. Advantages • This method is appropriate for small depth lowering. • The greatest depth to which water table can be lowered by this method is 8m below the pump level • It is most widely used and economical of all methods of ground water lowering.
- 7. Disadvantages • In areas with steep slopes, this method is not demanded. • This method will bring collapse of slopes and causes dangerous problems.