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Grip length and its importance

Short answer

Grip length is the depth of well below maximum scour level, at least one-third of the maximum scour depth. It provides lateral stability through passive soil resistance, safety against unexpected scour, fixity to reduce tilt and settlement, and ensures the base rests in firm undisturbed soil.

What do you understand by grip length? What is its importance in well foundation?

Grip length is the depth of the well foundation below the maximum scour level (up to the bottom of the well). IRC practice takes it as at least 13\tfrac{1}{3} of the maximum scour depth (the scour depth is measured from HFL).

Importance

  • It gives the lateral stability: the passive resistance of the soil on the sides of the grip length resists the horizontal force and the overturning moment.
  • It gives safety against scour greater than expected, and protects the base of the well from exposure.
  • It provides fixity and reduces the tilt and settlement of the well.
  • It makes sure the base rests in firm, undisturbed soil.

✓ Answer checked by Claude Sonnet 5.5

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