The purpose of this experiment is to demonstrate the effect of loading on draine

Question

The purpose of this experiment is to demonstrate the effect of loading on drained and undrained soils. By using the apparatus you will be able to witness firsthand the effects of consolidation. Consolidation is the compaction of soil via the removal of water from the pore spaces as well as the deformation/displacement of the particles (figure 3). This usually requires a load to be placed onto the soil but there are other factors that can cause this effect. Consolidation is an important effect in civil design and the consequences of building a structure on poorly consolidated soil can lead to costly repairs (figure 4). The process of settlement is highly dependent on porosity (amount of pore spaces) of the sample. Large grained particles such as sand and gravel can be compacted relatively easily with almost instantaneous removal of water. Fine grained soils such as clay and silt have smaller particles. Therefore the flow of water between these particles is a much slower process due to the resistance caused by the pore space. An illustration of the settlement process is shown below, note the reduction in space between the particles as load is applied, what do you think will happen once the load is removed? Figure 3: Compaction of soil under external stress Figure 4: Examples of damages on houses caused by subsidence and settlements (Geoconsult, 2012),(Hulaproject.org, 2012)

Explanation / Answer

(1). It was harder to push the piston with water filled sponge. As when the air filled sponge is pushed down with piston, the air molecules in the sponge contracts, while in case of water filled sponge , the water molecules offer resistance being an incompressible fluid.

(2).As the piston is loaded it creates pressure on the sample and tries to consolidate it. As a result the water filled in the spaces come out, which makes the water table rise.

(3). When the release valve is open the water comes out of it and gets accumulated in the overflow beaker. The material gets deformed upto some extent due to pressure applied by piston which in result makes the sample compact by expelling out the water from it pores.

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