Debris flow generally occurs in rivers in mountainous areas. This flows is a very dangerous and
destructive. This happens because the debris flow has a high speed and carry a mixture of
sediment and other materials. Of infrastructure is built on rivers area flow pattern makes the need
for special handling to maintain the protected structure with a substantial investment. This study
focuses on the modeling and observation influence debris flow on bridge piers with three (3)
conditions: unprotected bridge piers, using gabion protection, and bored pile protection on the
model.
By using a discharge of 1.54 liters/sec on a scale model of the maximum scours depth is obtained
that occurred on bridge piers unprotected condition, that is equal to 1.7 cm and the minimum
scours occurs in conditions of safety piers the bored pile is equal to 1.48 cm. The maximum scours
volume occurs in the downstream bridge using gabion protected, amounting to 400 cm 2 , while the
minimum volume of sediment scours occurs by using a safety bored pile 257.5 cm 3 . By the using
protected piers bored pile more effective to resist scours due to debris flows. This is due to the
construction of bored pile does not impede the flows that occurs so that the effect scours will
reach a point of equilibrium