Critical Condition of Slope Stability During Reservoir Operation

The stability of a slope is a crucial aspect of any dam construction. The most critical condition for the slide of the upstream (U/S) slope is the sudden drawdown of the reservoir. This is due to the following reasons:

Sudden Drawdown

When the reservoir is full, the water on one side of the slope exerts pressure on the soil particles, holding them together. However, when the water level suddenly drops, the pressure on the soil decreases, causing the particles to lose cohesion and stability. This sudden decrease in pressure can also generate pore water pressure, which can further reduce the stability of the slope.

Other Conditions

While steady seepage conditions and reservoir full conditions can also affect slope stability, they are not as critical as sudden drawdown. In steady seepage conditions, the water pressure is relatively constant, and the slope can adjust to this condition over time. Similarly, in the reservoir full condition, the slope is stable due to the pressure exerted by the water.

Prevention and Mitigation Measures

To prevent the slide of the U/S slope during sudden drawdown, several measures can be taken. These include:

- Limiting the rate of drawdown to avoid sudden changes in pressure
- Implementing drainage measures to reduce the pore water pressure
- Reducing the slope angle to increase stability
- Using geotextiles or other reinforcement materials to improve soil strength

Conclusion

In conclusion, the most critical condition for the slide of the U/S slope during reservoir operation is the sudden drawdown of the water level. This can cause a sudden decrease in pressure and pore water pressure, leading to a loss of slope stability. However, with proper prevention and mitigation measures, the risk of slope failure can be minimized.