CHAPTER-1

FOUNDATIONS

• Q1: Define Foundation.
  Ans:The lowest part of a structure that transfers the load of the building safely to the soil below is called Foundation or Sub-structure.
• Q2: Enlist types of foundation.
  Ans:Some of the types are:

  • ➔ Shallow Foundation
  • ➔ Deep Foundation
• Q3: Define a shallow foundation.
  Ans:A foundation placed at a shallow depth (less than 3 meters), used when the soil has sufficient bearing capacity near the ground surface.
• Q4: Define a deep foundation.
  Ans:A foundation constructed at a greater depth (greater than 3 meters) when surface soil cannot support loads; examples include pile, pier, and caisson foundations.
• Q5: Differentiate between shallow foundation and deep foundation.
  Ans:
  Shallow: Depth <= width, suitable for good surface soil.
  Deep: Depth > width, suitable for weak surface soil requiring load transfer to deeper strata.
• Q6: Enlist four purposes of foundation providing underground.
  Ans:Following are some purposes:

  • ➔ Transfer building load to soil
  • ➔ Prevent settlement
  • ➔ Provide stability against sliding/overturning
  • ➔ Distribute loads uniformly
• Q7: Enlist types of spread foundation.
  Ans:The types are:

  • ➔ Wall footing
  • ➔ Column footing
  • ➔ Combined footing
  • ➔ Raft/Mat foundation
• Q8: Define grillage foundation.
  Ans:A type of foundation using layers of steel or timber beams to distribute heavy loads over a large area at shallow depth is called Grillage foundation.
• Q9: Write about raft foundation.
  Ans:A large concrete slab covering the entire area beneath a structure, used when loads are heavy or soil has low bearing capacity is Raft foundation.
• Q10: Define stepped foundation.
  Ans:A foundation provided in steps on sloping ground to maintain the level of the structure is called Stepped foundation.
• Q11: Give a traditional formula to determine the width of the foundation.
  Ans:
• Q12: Write Rankine formula for determining depth of foundation.
  Ans:
• Q13: Write formula to determine depth of concrete block in design of foundation.
  Ans:
• Q14: What is the bearing capacity of soil?
  Ans:The maximum load per unit area that soil can safely carry without shear failure or excessive settlement is called bearing capacity of soil.
• Q15: Define ultimate bearing capacity of soil.
  Ans:The maximum pressure soil can withstand before failure occurs is called the ultimate bearing capacity of soil.
• Q16: Define safe bearing capacity of soil.
  Ans:The maximum pressure that can be safely applied to soil considering the factor of safety is called safe bearing capacity of soil.
• Q17: Define sub soil investigation.
  Ans:The process of studying soil properties, stratification, and groundwater conditions below the surface before construction.
• Q18: Give purpose to soil investigation.
  Ans:Soil investigation is done to:

  • ➔ Determine soil bearing capacity
  • ➔ Classify soil type and properties
  • ➔ Locate groundwater table
  • ➔ Ensure safe and economical foundation design
• Q19: Write methods of boring.
  Ans:Some methods are:

  • ➔ Auger boring
  • ➔ Wash boring
  • ➔ Percussion boring
  • ➔ Rotary boring
• Q20: Why is the bearing capacity of soil determined?
  Ans:To ensure the soil can safely support structural loads without risk of failure or excessive settlement.
• Q21: Enlist some causes of failure of foundation.
  Ans:Some of the causes are:

  • ➔ Unequal settlement of soil
  • ➔ Earthquakes
  • ➔ Transpiration of trees and shrubs
  • ➔ Poor quality material
  • ➔ Lateral load of superstructure
• Q22: Name methods to determine bearing capacity of soil in the field.
  Ans:The methods are:

  • ➔ Plate load test
  • ➔ Standard penetration test (SPT)
  • ➔ Cone penetration test (CPT)
  • ➔ Vane shear test
• Q23: Define Isolated Footing.
  Ans:Isolated footings are used to support one column only.
• Q24: Define Combined Footing.
  Ans:Combined footings are used to support two columns. These footings are made when the distance between the columns is very small.
• Q25: Name the loads on foundation.
  Ans:Foundations bear the following loads:

  • ➔ Dead Load
  • ➔ Live Load
  • ➔ Wind Load
  • ➔ Self Load
• Q26: Name some types of Pile foundations.
  Ans:Some of the types are:

  • ➔ Wooden Pile
  • ➔ RCC Pile
  • ➔ Concrete Pile
  • ➔ Bearing Pile
  • ➔ Fraction Pile
• Q27: What is the other name of Raft Foundation?
  Ans:Raft foundation is also known as Matt Foundation.
• Q28: Define Frame structure.
  Ans:A structure that has beams and columns to support the load and walls are non-load bearing.
• Q29: Define Grade Beam.
  Ans:A grade beam is a reinforced concrete beam that is constructed at ground level (or slightly below) and supports a wall by distributing its load to spaced foundations such as pile caps or caissons.
• Q30: Define Plinth Beam.
  Ans:A plinth beam is a reinforced concrete beam constructed at the plinth level (just above ground level) to support walls and prevent differential settlement.
• Q31: Define Joist.
  Ans:A joist is a horizontal structural member used in framing to span an open space, often between beams, and to support a floor or ceiling.
• Q32: Define Cantilever Footing.
  Ans:It is a type of foundation that extends horizontally to support a load without external support on one side.