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Spread footings have a base that is wider than a typical load-bearing wall ______.
foundation
Raft foundations are spread across the entire area of the building to support heavy ______ from columns and walls.
structural loads
Pile foundations transfer heavy loads from the structure to a hard rock ______ much deeper below the ground level.
strata
The use of mat foundations can prevent differential ______ of individual footings.
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Spread footings and wall footings are typically used where the bearing soil layer is within ______ from the ground surface.
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Soil bearing capacity must be sufficient to support the weight of the ______ over the base area.
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Pile foundations are generally needed in conditions where the surface soil is not suitable for ______ loads.
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Raft foundation is economical when one-half area of the structure is covered with individual ______.
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The most common type of foundation used for building construction is called an ______.
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When two or more columns are close enough, a ______ footing is constructed that overlaps their isolated footings.
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The shape of an individual footing can be square or ______.
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The ______ foundation is used when the structure's loads are carried by many columns and tends to be deeper.
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A ______ foundation includes systems like pile foundations and drilled shafts or caissons.
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The ______ foundation aids in distributing loads across a larger area compared to individual footings.
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In ______ foundations, the size is calculated based on the load on the column and the safe bearing capacity of the soil.
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An isolated footing is also known as a ______ foundation.
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The ______ transmits loads from columns and walls to the solid ground.
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If one ______ fails, it can lead to the potential collapse of the entire structure.
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Beams carry loads from slabs and also direct loads such as masonry walls and their own ______.
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Shear walls act similarly to very large ______ to withstand horizontal loads.
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The loads carried by columns may be ______ or eccentric.
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Foundations are critical for the load ______ of a building.
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The ______ of a structure includes foundations, beams, and columns.
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Elevator shafts are vertical concrete ______ in which elevators are provided to move up and down.
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Study Notes
Boring Methods
- Auger Boring: A method used for drilling holes in the ground.
- Wash Boring: A method that uses a water jet to remove soil and rock.
- Percussion Boring: A method that uses a hammer to drive a drill bit into the ground.
- Core Boring or Rotary Drilling: A method that uses a rotating drill bit to extract core samples of the ground.
Geophysical Methods
- Used for deep exploration and rapid investigation.
- Common methods include:
- Gravitational methods: Measure variations in gravity to identify underground structures.
- Magnetic methods: Detect variations in the Earth's magnetic field to map geological formations.
- Seismic refraction method: Analyze the travel time of seismic waves to determine the layering and properties of the ground.
- Electrical resistivity method: Measures the resistance of the ground to an electric current to identify different soil types and water content.
- Seismic refraction method and electrical resistivity methods are commonly used in civil engineering.
- These methods are non-intrusive ways of "seeing" into the ground.
- Can be used to identify subsurface hydrological, geological, and contaminant conditions.
Factors Affecting Sample Disturbance
- Area Ratio: The ratio of the borehole cross-sectional area to the sample cross-sectional area.
- Inside Clearance: The space between the borehole wall and the sample.
- Outside Clearance: The space between the sampling tool and the borehole wall.
- Inside Wall Friction: The friction between the sample and the borehole wall.
- Design of Non-Return Valve: The design of the valve that prevents the sample from being lost during retrieval.
- Methods of Applying Forces: The way in which forces are applied during sampling.
- Recovery Ratio: The ratio of the length of the recovered sample to the total length of the sample.
Types of Foundations
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Shallow Foundations:
- Individual Footing or Isolated Footing: Used for a single column and supports loads from structures.
- Combined Footing: Used when two or more columns are close together and their isolated footings overlap.
- Strip Foundation: Runs along the length of a wall, used for supporting walls and bridge piers.
- Raft or Mat Foundation: Spreads across the entire area of a structure to support heavy loads.
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Deep Foundations:
- Pile Foundation: Used to transfer heavy loads deep into the ground to rock strata.
- Drilled Shafts or Caissons: Created by drilling a hole and filling it with concrete to provide support.
Shallow Foundations
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Individual Footing or Isolated Footing:
- Most common type of foundation used for building construction.
- Also known as a pad foundation.
- Shape is typically square or rectangular.
- Size is calculated based on loads and soil bearing capacity.
- Rectangular footings are used when they experience moments due to eccentric loads or horizontal forces.
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Combined Footing:
- Used when two or more columns are close together and their footings overlap.
- Has a rectangular shape.
- Supports loads from structures.
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Spread Footings or Strip Footings and Wall Footings:
- Have a wider base than standard load-bearing wall foundations.
- This wider base spreads the weight from the structure over a larger area, providing better stability.
- Used for individual columns, walls, and bridge piers where the bearing soil layer is within 3 meters (10 feet) of the ground surface.
- Soil must be able to support the weight of the structure.
- Should not be used on soils where there is a possibility of groundwater flow above the bearing layer, which can cause scour or liquefaction (loss of strength).
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Raft or Mat Foundations:
- Spread across the entire area of a building to support heavy structural loads from columns and walls.
- Used when loads from columns and walls are extremely high.
- Prevents differential settlement (uneven sinking) of individual footings.
- Suitable for expansive soils with low bearing capacity that cannot support spread footings or wall footings.
- Economical when half of the structure's area is covered with individual footings and wall footings.
- Should not be used where the groundwater table is above the bearing surface of the soil, as this could lead to scour or liquefaction.
Deep Foundations
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Pile Foundations:
- Used to transfer heavy loads from the structure to hard rock strata deep below the ground level.
- Used when shallow foundations are not suitable due to weak soil conditions near the surface.
- Can also help prevent uplift of the structure due to lateral loads like earthquakes and wind.
- Used when the ground is very weak, and shallow foundations would not be effective.
- Used when there is a possibility of uplift of the structure, as pile foundations can resist these forces.
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Drilled Shafts or Caissons:
- Created by drilling a hole in the ground and filling it with concrete.
- The concrete shaft provides support for the structure.
- Used when the groundwater table is high, and the soil is unstable.
- Used when there is a possibility of uplift of the structure.
Other Important Structural Elements
- Beams: Horizontal members that carry loads from slabs and masonry walls.
- Columns: Vertical members carrying loads from beams and upper columns.
- Foundation: The load transmitting member, transferring loads from columns and walls to the ground.
- Shear Walls: Large columns that resist horizontal loads like wind and earthquakes (work in one direction only).
- Elevator Shaft: Vertical concrete boxes for elevators.
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Description
This quiz explores various boring methods such as auger, wash, percussion, and core boring as well as geophysical techniques like gravitational and magnetic methods. Understand how these methods aid in geological exploration and soil analysis. Test your knowledge and learn more about the principles behind these essential drilling and surveying techniques.
