Heaving or Squeezing
Bottom heaving or squeezing is caused by the downward pressure created by the weight of adjoining soil. This pressure causes a bulge in the bottom of the cut, as illustrated below. Heaving and squeezing can occur even when shoring or shielding has been properly installed.
![Example of Heaving](images/20180607_001_802_heaving_squeezing.png)
![Example of Heaving](images/20180607_001_802_heaving_squeezing.png)
![Example of Heaving](images/20180607_001_802_heaving_squeezing.png)
Boiling
Boiling is evidenced by an upward water flow into the bottom of the cut. A high water table is one of the causes of boiling. Boiling produces a "quick" condition in the bottom of the cut and can occur even when shoring or trench boxes are used.
![Example of Boiling](images/20180613_004_802_boiling.png)
![Example of Boiling](images/20180613_004_802_boiling.png)
![Example of Boiling](images/20180613_004_802_boiling.png)
Knowledge Check Choose the best answer for the question.
3-5. Which soil failure is caused by a high water table?
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