## Slope Stability

Natural slopes tend to slide or fall to their lower side, given long enough time. Depending on the saturation degree of soil, the slope angle, overall 3D geometry, and the soil material itself, this sliding or falling can happen in very different ways and speeds, some can be very slow and virtually harmless, and some […]

## Consolidation Settlement

Consolidation settlement is a time dependent settlement that occurs in clay soils, due to applied loads  from above. As we wrote before, settlement of soils in general has three stages: The immediate settlement as the load is applied, which is elastic settlement, the gradual, slow consolidation settlement while water is escaping through soil pores, and […]

## Elastic Settlement

After finding stresses in soil, we can calculate settlement amount. Settlement of soils in general has three stages: The immediate settlement as the load is applied, which is elastic settlement, (for all soils) the gradual, slow consolidation settlement while water is escaping through soil pores, (for cohesive soils only) and the secondary compression due to […]

## Stress Increase in Soils

We have looked at bearing capacity of the soil in the previous section but checking only that is not enough. We must also make sure that, even if the soil can bear the pressure, it will not settle too much.  Before calculating settlement amount in soil however, we must first know the stresses in soil. […]

## Bearing Strength of Soil

So far, under soil strength section, we have explained total and effective stresses, pore pressure, angle of internal friction, shear strength, lateral earth pressure coefficient, and cohesion of clay. Now we are ready to start seeing how these are actually used, when designing foundations.   In this subsection we will now learn about bearing strength, […]

## Cohesion of Clay

Cohesion, although thought to have only one meaning by many engineers, actually has two close meanings to each other. One meaning is in soil physics, which means, is the attraction of particles in soil, creating a sticking action. The other meaning comes for soil mechanics, and it means the shear strength of soil, when there […]

## Angle of repose

We talked about angle of internal friction of soil, in previous posts of this series. There is also the angle of repose, which is often confused with angle of internal friction. Angle of repose is the angle a soil forms with the horizontal, when poured over a surface in it’s loosest state. Although angle of […]

## Triaxial Test

A more complicated version of direct shear test which we talked about in the previous post, is called triaxial test, where you can also control the water drainage turning off or on, plus you can measure at what angle the sample will shear, which we will talk about more in the following paragraphs. Both of […]

## Direct Shear test

When we want to test the shear strength of soil vs. how much we press on it vertically, we can use a mechanism like below, which is called direct shear test. It is the most basic shear test method for soil. In it’s simplest from it can be shown as: Direct shear test is a […]

## Angle of Internal Friction

Think of this post as a direct continuation of the previous two posts of this series, shear strength of soil and lateral earth pressure. Now let’s present another very important characteristic of soil, the angle of internal friction, which we briefly mentioned already before in those sections. Let’s consider a block resting on a surface, […]