Shallow Aquifer - Weakening Foundation
Significant Cracks on Building Structure
During the testing of our newly developed chemical for waterproofing, we observed significant cracks in the basement of the newly constructed buildings in nearly all the metro cities of India. On investigation, we found that these buildings or their neighbouring buildings have incorporated Ground Water Recharge Wells.
On further investigation, we found that the said Ground Water Recharge Wells were not been designed by competent personnel. The management has given the contract to the lowest bidder.
Note: Ground Water System is very complex and needs an expert to design a sustainable Ground Water Recharge Wells.
How are these major basement cracks related to Ground Water Recharge Wells?
During the design of the Foundation, we all came up with the terminology Uplift Pressure or Hydrostatic Uplift, defined as an upward pressure applied to a structure that has the potential to raise it relative to its surroundings.
For Building Foundation design, we make sure that the downward load should be greater than the upward load due to hydrostatic load.
For this, we consider a safety margin of 25%.
Considering a downward load of 65 kg/m2, the safety margin of 25% will be about 16.25 kg/m2.
The said safety margin accounts for a 4.0 m change in the height of the water from the water table to the bottom of the building foundation, which is a practically infeasible situation.
However, the generated water pockets of about 4,000 Liters may lead to an imbalance of the forces and lead to cracks in the structure.