I know the normal process of how bored piles are normally constructed, but I need to know in case we have a water table at 1.5 m under the surface level and the pile must be at a depth of 25 m. How do they prevent the water from filling into the bored pit. Because when they pour concrete they must remove the water from the drilled pit but if the water keep filling the pit and at very deep depth how could they prevent this ?
One more question I was thinking about is How much does the strength of the concrete get affected in a pile (due to the presence of water and some unwanted soil in it) ?