When soil under compression and tension loadings, how does soil fail (orwhat is its failure mode)?

Soil failure under compression and tension loadings can occur in several ways, depending on the type of soil, the magnitude of the load, and the duration of the load. Here are the steps to understand how soil fails:

1. Compression Loading: When a soil is subjected to a compressive load, it tends to compact or consolidate. This is because the load forces the soil particles closer together, reducing the volume of air spaces between them. If the load is too great, the soil may undergo plastic deformation, meaning it will not return to its original shape once the load is removed. This is a type of failure known as compressive failure.

2. Tension Loading: Soil is generally weak in tension. When subjected to a tensile load, the bonds between soil particles can break, causing the soil to crack or fracture. This is a type of failure known as tensile failure.

3. Shear Loading: In addition to compression and tension, soil can also fail under shear loading. This occurs when one layer of soil slides past another. Shear failure is often the most critical type of failure for soil, as it can lead to landslides and other types of ground failure.

4. Bearing Capacity Failure: This is another common mode of soil failure. It occurs when the soil beneath a foundation or other load-bearing structure is unable to support the load placed upon it. This can lead to settlement or even collapse of the structure.

5. Slope Stability Failure: This type of failure occurs when the forces acting on a slope (such as gravity) exceed the strength of the soil making up the slope. This can lead to landslides and other types of slope failure.

In conclusion, the failure mode of soil under compression and tension loadings can vary widely, and is influenced by a number of factors including the type of soil, the magnitude and duration of the load, and the presence of water in the soil.