Field (in-situ) Soil Tests

Visual examination: By digging trenches, test pits, visual examination can be done. Visual examination is the first thing to be done, for obtaining soil data and it can be obtained from walking the site, while drilling holes, or from dug trenches or test pits. In terms of cost and schedule, test pits and trenches can […]

Subsurface Investigation

In order to design the foundation of structures, we must have good understanding of the soil conditions. The first step to this is to perform subsurface investigation. The most reliable and preferred way for this, is to see the actual soil, by taking samples. This can be done by drilling boreholes in the ground. The […]

Critical State of Soil

This is a relatively new (in comparison to many decades old of soil mechanics theories) but very useful concept in soil mechanics. It is a topic that is analysed in advanced soil mechanics courses only, in masters level classes, but it doesn’t prevent us from at least describing it, as it is good to know […]

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

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

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, […]

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