Ground Improvement technique Dewatering Methods

Ground Improvement technique

1. Dewatering Methods
Open sumps and ditches

2. Dewatering
•If water is leakinginto the trench
during foundationexcavation, it is very
important to dispose of it.
•If water is not removed from the
trench, it is difficult to make
concretingor masonryin the
foundation
•The action of removing waterfrom
the foundation is called dewatering.

3. Necessity of dewatering
•Ease of concretingor masonryin foundation.
•To prevent soil erosionaround the base.
•To protect concrete or masonry from the effects of water.

4. •The essential feature of this method
is a sumpbelow the ground level of
the excavation at one or more
corners. A small ditchis cut around
the bottomof the excavation, falling
towards the sump.
•The ditches size is usually 20cm in
diameterof a semicircle.
•Sumps are made at a distance of 40m
to 60min the ditches. The size of the
sumps is kept as 1m*1m*1m.

5. •The water flows into the ditches and collectsin 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 economicalof all methods of ground water
lowering.

7. Disadvantages
•In areas with steepslopes, this method is not demanded.
•This method will bring collapse of slopesand causes dangerous
problems.