Failure of weirs on permeable foundation
CAUSES OF FAILURE OF WEIRS ON PERMEABLE SOILS AND THEIR REMEDIES

Failure of weirs on permeable foundation

CAUSES OF FAILURE OF WEIRS ON PERMEABLE SOILS AND THEIR REMEDIES The weir failure may take place due to the following reasons 1. Piping or undermining. 2. By uplift pressure. 3. By suction due to standing wave. 4. By scour on the U/S and D/S of the weir. 1. Piping or undermining. When water seeping through the permeable foundation emerges out at the D/S end of the impervious floor of the weir, at hydraulic gradient or exit gradient greater than the critical value for the foundation soil, the soil starts boiling at the exit point. Boiling of the soil indicates lifting of the soil against gravity and it happens only when exist gradient of seeping water is greater than the safe limit for the foundation soil. The soil gets wash out with boiling water. With washing out of some soil from D/S side, the exit gradient increase and boiling of…

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