Section 4: Soil and Water Conservation Engineering
Gully Control and Drop Spillways
Subtopic: Drop Spillway Components
Question Statement:
In a structural drop spillway, cut-off walls and toe walls are provided primarily to:
Options:
(A) Prevent piping and seepage flow beneath the structure and resist sliding
(B) Increase the flow discharge over the weir crest
(C) Provide an anchor for trash racks
(D) Serve as decorative abutment facings
Answer Key:
A
Step-by-Step Solution & Explanation
Cut-off walls extend deep into firm subgrade to lengthen the percolation path (seepage creep length) to eliminate piping failure and anchor the floor against sliding under hydrostatic thrust.