Causes of slope protection on high-speed highway embankments include:

1. The subgrade foundation beneath the roadbed is an unstable natural sliding mass.

2. The road's embankments are too steep on both sides.

3. Incorrectly filling embankments using the incorrect slope grading method.

4. The soil is too moist, reducing its cohesion and internal friction.

5. The slope foot has been eroded by water.

6. Due to the stability disruption in certain rock sections caused by the construction of the highway, especially as the rock layers incline towards the road cut, followed by the destructive effects of water or earthquakes.

7. The rock stratum and composition on both sides of the highway are inherently unstable.

8. Landslide damage.