Building Foundations, Soil Survey, Types of Foundations

University Of Engineering And Technology Peshawar, Pakistan
CE-120
Building Construction Engineering
Instructed By: Engr Arsalaan Khan
Presented By: Asmar-ud-Din
Semester: 2nd
Department Of: Civil Engineering
Registration No: 19pwciv5272

“Topics”
Definition Of Foundation
Types Of Foundation
Purpose Of Foundation
Foundation Soil
Types Of Soil
Subsoil Investigation
Purposes Of Soil Investigation
Different Methods Of Soil Investigation
“Introduction To Building Foundation, Types Of
Foundation Soil, Subsoil Investigation”

Definition Of Foundation
Foundation is the lowest artificially built sub-structure of the building
which support the weight of building and transmits the load to the soil
or rock lying underneath.
Foundation is always constructed below the ground level in order to
increase the lateral stability of the building.
The solid soil on which the foundation rests is called Foundation bed.

Types Of Foundation
There are two main types of foundations
1. Shallow foundations
2. Deep foundations
We will see in detail about these types of foundation later on.

Purposes Of Foundation
All the engineering structures are provided with the foundations at the
base to fulfill the following purposes.
To distribute the load of the structure over a large bearing area so as to
bring intensity of loading within the bearing capacity of the soil.
To load the bearing surface at a uniform rate, so as to prevent unequal
settlement.
To prevent the lateral movement of the supporting materials.
To increase the lateral stability of the buildings.
To increase the stability of the structure as a whole.

Foundation Soil
The earth surface consists of mineral materials mostly incombustible
and inorganic.
In rocks the minerals are firmly bonded together. Soil is the form of
individual particles produced by the disintegration of the rocks. In most
of the location the top layer of the ground consists of soil and rock
generally occur deep under the surface.
Hence foundations of most buildings are soil supported, except where
the soil strength is inadequate.

Types Of Soil
The soils forming foundation beds of various buildings or structures are
generally classified into different types
Different types of soils are Gravel/Shingle, Sand, Silt, Clay, Alluvial Soil,
Black Cotton Soil, Reclaimed Soil.
According to building code of Pakistan BCP SP-2007 foundation soils can be
of the following
Type SA = Best Soil or Hard Rock
Type SB =Rock
Type SC= Very Dense Soil or Soft Rock
Type SD=Stiff Soil
Type SE =Soft Soil
Type SF=Soil Require Specific Evaluation

Subsoil Investigation
Subsoil investigation is also called geotechnical investigation, Soil
Survey or soil exploration.
Process of investigation of soil and rock strata and ground water
condition below a ground at site to obtain necessary data for safe and
economical design of foundations.
Purpose Of Soil Investigation
Purpose of geotechnical investigation is to find
1.Thickness and variation in the composition of soil
2.Depth and type of rock
3.Seasonal Variation in water

Different methods of soil investigation
The soil can be investigate or inspected through different methods
1.General inspection
2. Test Pit Method
3.Probing Method
4.Boring Method

1.General Inspection
It is the qualitative assessment through which general information about
the following is collected
Nature of Soil, whether the soil is soft, hard or water logged.
Type of soil
Drainage condition in the area
Existing bores or wells in the neighborhood

2.Test Pit Method
This method consists of digging a pit/ditch which is large enough to
permit the entry of persons for the direct inspection of soil properties of
an undisturbed soil.
Pits are usually square having the dimension
of 5′×5′×10′(1.5m×1.5m×3m)
Pits are usually excavated below the level of
water.
This method is usually adopted for buildings
with shallow foundations.
Test Pit is prepared and soil is collected for
Laboratory testing.

3.Probing Method
In this method of subsoil investigation, usually a rod of about 25-
40mm diameter with a pointed end is driven into the ground until a
hard stratum is met with. Sometime hollow tube of about 35-50mm
diameter having a slit of 3mm thickness in the bottom portion of
600mm is also used in place of steel rod.
The steel bars or the hollow tubes are driven
out of the ground and idea about the nature of
soil is obtained by investigating the soil sticking
on the tube or rod.

4.Boring Method
This method involves the boring of ground in order to take the sample
of soil for testing
Different types of boring are adopted for the collection of soil
1.Auger Boring
2.Wash Boring
3.Percussion Boring
4.Core Drilling

1.Auger Boring
Here in this method of soil survey an auger of different types like
posthole, screw augers are used. The auger is held vertically and driven
into the ground by rotating its handle. During the process of rotation the
auger is pressed into the ground. After every penetration the auger is
taken out with soil sample for testing.

2.Wash Boring
In this method of boring of soil investigation, a hollow steel pipe known as
casing pipe or drive pipe, is driven into the ground and the material inside the
casing is washed out and brought to the surface for inspection.
3.Percussion Boring
In this method of boring of soil investigation the sub-strata is broken by
repeated blows by means of a bit or chisel. The material thus pulverized, is
turned into slurry by pouring water in the bore hole. The slurry is removed
from the hole and dried for examination.
4.Core Drilling
In this method a hole is made by rotating a hollow tube having a cutting bit
or edge at its bottom. The cutting bit forms an annular cut in the strata of the
soil and leaves a cylindrical core of material in the hollow tube.

“Knowledge Will Give You Power But Character Respect”
Bruce Lee

Building Foundations, Soil Survey, Types of Foundations

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