1.
The total vertical stress acting at a point below the ground surface is due to
the weight of everythinglying above: soil, water, and surface loading. Total
stresses are calculated from the unit weight of the soil.
2. The ratio, expressed as a percentage, of the amount of consolidation at a given time
within a soil mass, to the total amount of consolidation obtainable under a given stress
condition.
3. Consolidation Settlement• It occurs due to the process of consolidation.• Clay and Organic
soil are most prone to consolidation settlement.• Consolidation is the process of reduction in
volume due to expulsion of water under an increased load.• It is a time related process
occurring in saturated soil by draining water from void.• It is often confused with
Compaction.• Consolidation theory is required to predict both rate and magnitude of
settlement.
4. Secondary compression is a continuation of the volume change that
started during primary consolidation, only it usually occurs at a much
slower rate. Secondary compression is different from primary
consolidation in that it takes place at a constant effective stress, that is,
after essentially all the excess pore pressure has dissipated. For
general definitions, remarks and types of settlement refer to Settlement
types, definitions, and general equation article.
5. Compression Index
It describes variation of the void ratio e as a function of the change of effective
stress σef plotted in the logarithmic scale:
6.well index is also called as free swell index. When the volume of the soil increases without any
application of external forces or water pressure, it is called as free swell. The index will measure the
increase in volume with respect to the original volume.
7. Overconsolidation ratio
Overconsolidation ratio is defined as the ratio of past maximum stress
and present existing stress. The existing stress in a soil can be
computed based on the effective stress method. In the past, the soil
most probably would have been subjected to a much higher stress.
8. A structural foundation is the part of a building that fixes it into the soil. These structures provide
support for the main structures that appear above the soil level, much like the roots of a tree support
the stem.
One of its functions is to transfer loads from the structure to the ground. For example, slabs transfer
their weight to girders, which in turn transfer that load as well as loads applied to them to the beams.
Beams transfer that load and any additional loads applied to them to the columns, and finally,
columns transfer that load to the foundations.
One of the duties of civil engineers is to consider the bearing capacity of the soil, and design these
foundations to resist shear stress, overturning, and sliding.
9Footings are an important part of foundation construction. They are typically made of concrete
with rebar reinforcement that has been poured into an excavated trench. The purpose of
footings is to support the foundation and prevent settling. Footings are especially important in
areas with troublesome soils.
10. A shallow foundation is a type of building foundation that transfers building loads to the earth
very near to the surface, rather than to a subsurface layer or a range of depths as does a deep
foundation. Shallow foundations include spread footing foundations, mat-slab foundations, slab-on-
grade foundations, pad foundations, rubble trench foundations and earthbag foundations.
11. earing capacity is the capacity of soil to support the loads applied to the ground. The bearing
capacity of soil is the maximum average contact pressure between the foundation and the soil which
should not produce shear failure in the soil. Ultimate bearing capacity is the theoretical maximum
pressure which can be supported without failure; allowable bearing capacity is the ultimate bearing
capacity divided by a factor of safety. Sometimes, on soft soil sites, large settlements may occur
under loaded foundations without actual shear failure occurring; in such cases, the allowable bearing
capacity is based on the maximum allowable settlement.
12. Net Bearing Capacity is calculated by subtracting the over burden pressure from the
Gross Bearing Capacity. It can be understood in this way that a part of Gross Bearing
Capacity is used up in supporting the soil overburden, hence usable Bearing Capacity is the
remaining bearing capacity value of soil after overburden pressure is deducted. Hence:
