When we talk about Slopes we mean any surface that was inclined with respect to the horizontal. There are numerous types of slopes, both natural and artificial, and they can take a temporary or permanent form depending on their nature.
In this article we are going to tell you about the types of slopes, how they are formed and their main characteristics.
Main types of slopes
A surface that is inclined with respect to the horizontal is considered a slope. There are natural slopes that have a structure formed by soil or rock. On the other hand, there are artificial slopes created with cement, asphalt, or other elements and used to create uneven surfaces out of necessity or convenience.
We are going to differentiate which are the main types of slopes:
- Natural: are those that are formed in nature through the various geological agents that act on soils and bedrock.
- Artificial: They are those that are created from the hand of man. They mainly have objectives to be able to build roads, dams, railways, embankments, etc.
When constructing a slope for a dam, whether made of rock or earth, a very detailed prior design study is required. Just consider that if we create a slope to contain the waters of a reservoir, said slope must be able to support the weight of the water without breaking. Otherwise, if a dam fails, all the water could rush out and affect the population downstream. Furthermore, the stability of these slopes is related to the topography of the surrounding terrain, considering the impact of heavy rains that can cause flooding in nearby areas, as mentioned in floods in torrevieja.
Slope design should have a limit and a thorough analysis. The first is to assume a failure surface. As we know, the most seismically active zones are located on the surface of faults. This can cause earthquakes that can destroy slopes. One of the fundamental aspects of slope design is the application of the different criteria of the resistance of materials. The slopes are built with different materials. You have to compare the resistance of each material with the one that is built, adapting it to any mechanism that may fail.
Most common types of slope failure
A slope failure occurs through a sliding of the soil mass. This mass acts as a rigid solid body that slides along the fault. This can significantly affect the slope's stability. Let's analyze the most common types of failure:
- Failure by a shallow landslideThis type of failure also depends on the weather and climate of the region. In this case, meteorology plays a significant role when constructing a slope. If a region's climate is rainier, the risk of a surface landslide increases more frequently.
- Landslide on natural slopes on pre-existing fault surface: it is usually easier for faults to appear on slopes that are already formed by slope deposits naturally. Sometimes these deposits are located on other firmly laminated materials.
- Slope movement failure: are those that take place through the movement of the slope either by various external agents such as water or wind.
- Rotation failure: it is a curved surface along which slope movement takes place.
- Translational failures: It occurs along weaker surfaces with less resistant materials. The surface is usually horizontal or slightly inclined.
- Flow: This flow is very similar to that of a viscous liquid such as lava or honey and can occur on an uncemented surface.
- Erosion failure: The continuous drag of wind and water can cause a surface to fail. It's important to keep in mind that for this to happen, the action of these geological agents must be very intense and widespread over time.
- Liquefaction failure: it takes place when it has a more or less firm shape than that of a suspension.
- Bearing capacity failure: occurs when a structure with greater weight is built on top of what the slope can support.
Cause of movements
When we see a movement of slopes it is necessary to analyze well what are the causes of it. Let's see what they are:
- Unstable floors: They tend to move towards the bottom, acted upon by the force of gravity or other forces or loads that are greater than their holding capacity.
- Non-cohesive soils: These are soils with a granular texture or pure sand in which the failure surface is flat. Slopes built on non-cohesive massifs will be stable as long as the slope's inclination angle is less than the angle of internal friction of the sand or granular surface.
Natural slopes come in different shapes. These are rarely homogeneous slopes or slopes without stratification. They are also not chemically stable and are usually overconsolidated soils. One of the main characteristics of natural slopes is that they present fissures and cracks that form weaker points in the structure. Therefore, they are said to have no stratification.
The soils in which slopes most frequently form are loose soils, moist sands, loose silt deposited on clays, soils with fissured clays, and hard soils with fissured clays. On natural slopes, the causes of movement are usually due to the following factors:
- Weight gain
- Decreased issue of materials
- Increase in porosity due to excess erosion
- Shear decrease
These causes are increased by some agents that predispose and facilitate sliding. These agents are the geological formation, the topography of the terrain, the weather, the water cycle, gravity, the difference in temperatures and the type of vegetation.
I hope that with this information you can learn more about the slopes and their characteristics.