For effective drainage in a tunnel, it is generally preferred to provide
- AA perfectly flat longitudinal profile to prevent water flow.
- BLarge open ditches in the center of the roadway.
- CA slight longitudinal slope to allow water to flow by gravity to a sump or portal.Correct
- DHigh-pressure pumps at every 10 meters of tunnel length.
Solution
Concept
Tunnel Drainage System
Formula
N/A
Step-by-step solution
1. Identify the question regarding the preferred method for effective tunnel drainage. 2. Recall that providing a slight longitudinal slope allows water to flow naturally by gravity to sumps or portals. 3. Select Option C as the correct choice.
Explanation
Providing a slight longitudinal slope allows water inside the tunnel to drain naturally by gravity toward a sump or the tunnel exit, preventing water accumulation simply and effectively without relying entirely on continuous pumping.
Shortcut
To remember tunnel drainage design, use the rule "Slope for Flow, Gravity to Go": - Slope & Gravity: A slight longitudinal slope allows water to drain naturally by gravity to a sump or portal, preventing water ponding without relying on costly pumping systems.
Common mistake
A common mistake is selecting Option A by assuming a flat profile simplifies construction, ignoring that a zero slope leads to water stagnation and ponding inside the tunnel. Another frequent error is choosing Option D by overestimating the reliance on mechanical pumping systems, whereas civil engineering design prioritizes natural gravity flow using a slight longitudinal slope to minimize operational costs and maintenance.
Correct answer: C) A slight longitudinal slope to allow water to flow by gravity to a sump or portal.