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Experiment One 2019
Construction Technology 2 (Substructure) (300721)
Western Sydney University
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Sandy soils have a significantly higher coefficient of friction compared to clayey soils, due to having rough particles eliminating the chance of slipping, whereas clay soils have smoother particles increasing the chance of the particles slipping and moving. Therefore, sandy soils also have a greater angle of repose compared to clay soils due to their greater frictional resistance.
c (Mohr) = 0
c (Coulomb) = 5.
The C value represents the soil cohesion level. The C value will increase proportionally to the increase in Normal Stress and Shear Stress in sandy soils. However, the opposite will occur with Clayey soils, where a constant C value will be exhibited, no matter the Shear Stress and Normal Stress values, as clay is significantly more cohesive than sandy soils.
Mohr and Coulomb tests significantly relate to various real foundation soils under real buildings, as it allows us to understand how certain soils and clays will behave when load and force is applied to them. For example, the tests can help determine how soil will move when its load bearing capacity is exceeded. Additionally, the experiments show the way in which frictional and cohesive bonds develop in the soil. Moreover, the tests display how the soil forms a slip zone below footings and the way in which soil strips closest to the slip zone will move significantly quicker.
Doubling the width of a strip footing will ultimately expand the zones of bearing failure. The size of the slip surface in zone 2 will become larger and ultimately will allow more frictional and cohesive forces to be built up on the surface, before a failure occurs. Moreover, within zone 3, a larger quantity of soil must be moved outwards and up towards the surface, before the footing will fail.
Although it would seem that ground heave would occur equally on both sides of the footing, this is not the case due to the structure that is held up by the footing, will ultimately begin to fall to one side once the bearing capacity of the soil is exceeded and thus continually further placing more load to one side of the footing. Therefore, causing the a significantly larger bulge on one side of the footing, as the bearing capacity of the soil is continually being exceeded as the footing fails.
Additionally, ground heave can be accelerated through groundwater under the footing which disrupts the cohesion of the soil particles. This is caused by the gaps between the particles being filled with water. Accordingly, if groundwater is present beneath one side of a footing it will most likely collapse and create a bulge on that side of the footing.
Experiment One 2019
Course: Construction Technology 2 (Substructure) (300721)
University: Western Sydney University
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