Day 11 Foundations in Construction Management – ECET 2026 Civil

Why this topic is important for ECET?

Foundations form the base of every structure. If the foundation fails, the entire building becomes unsafe. In ECET 2026 Civil exam, questions from Construction Technology & Management often test your basics of foundation types, design principles, and suitability for soils. A clear understanding ensures you can solve both conceptual and numerical problems quickly.

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📘 Concept Notes

1. Introduction to Foundations

• Definition: Foundation is the lowest part of a structure that transmits loads from the superstructure safely to the ground.
• Purpose:
  • Transfer load to soil.
  • Prevent settlement.
  • Provide stability against sliding & overturning.

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2. Types of Foundations

1. Shallow Foundations (depth ≤ 3 m)
   • Spread footing
   • Combined footing
   • Mat (raft) foundation
   • Strap footing
   • Wall footing
   Best for: Strong soils near the surface.
2. Deep Foundations (depth > 3 m)
   • Pile foundation (friction or end-bearing)
   • Well foundation
   • Caisson foundation
   Best for: Weak soils, heavy loads, bridges, waterfront structures.

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3. Depth of Foundation

• Rankine’s Formula:
  
  where:
  DfD_fDf​ = depth of foundation,
  qqq = loading intensity,
  γ\gammaγ = unit weight of soil,
  ϕ\phiϕ = angle of repose.

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4. Bearing Capacity of Soil

• Ultimate Bearing Capacity (qᵤ): Maximum pressure soil can withstand.
• Safe Bearing Capacity (qₛ):

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5. Settlement Criteria

• Total settlement: Within 25 mm (for isolated footings).
• Differential settlement: Must be minimal to avoid cracks.

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6. Pile Foundations

• Used when soil is weak at shallow depth.
• Capacity of single pile:
  
  where
  QbQ_bQb​ = end-bearing resistance,
  QfQ_fQf​ = skin friction resistance.

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Example

A footing transmits 300 kN on soil with SBC = 150 kN/m². Find area required.

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⚙️ Formulas

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🔟 10 MCQs

Q1. The primary purpose of a foundation is to:
a) Carry live load
b) Transmit load safely to soil
c) Reduce superstructure weight
d) Improve aesthetics

Q2. Which is NOT a shallow foundation?
a) Spread footing
b) Mat foundation
c) Pile foundation
d) Strap footing

Q3. Safe Bearing Capacity is:
a) Less than Ultimate Bearing Capacity
b) More than Ultimate Bearing Capacity
c) Equal to Ultimate Bearing Capacity
d) Independent of soil strength

Q4. According to Rankine’s formula, foundation depth depends on:
a) Load intensity & soil unit weight
b) Cement grade
c) Beam span
d) Water table

Q5. For isolated footings, maximum permissible settlement is:
a) 10 mm
b) 25 mm
c) 50 mm
d) 100 mm

Q6. A column load is 500 kN, SBC of soil is 200 kN/m². Required footing area = ?
a) 1.5 m²
b) 2.0 m²
c) 2.5 m²
d) 3.0 m²

Q7. The load-carrying capacity of a pile is the sum of:
a) Self-weight + Soil weight
b) End-bearing + Skin friction
c) Lateral resistance + Settlement
d) Soil cohesion + Water pressure

Q8. Differential settlement is dangerous because:
a) It increases depth
b) It causes cracks
c) It reduces cement strength
d) It increases load capacity

Q9. Well foundations are mostly used in:
a) High-rise buildings
b) Bridge piers
c) Residential houses
d) Water tanks

Q10. If ultimate bearing capacity is 450 kN/m² and FOS = 3, safe bearing capacity = ?
a) 100 kN/m²
b) 150 kN/m²
c) 225 kN/m²
d) 300 kN/m²

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✅ Answer Key

Q	Answer
1	b
2	c
3	a
4	a
5	b
6	b
7	b
8	b
9	b
10	b

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🧠 Explanations

• Q1: Foundation’s role is to transmit load safely → (b).
• Q2: Pile foundation = deep type, not shallow → (c).
• Q3: Safe < Ultimate because FOS is applied → (a).
• Q4: Rankine’s formula uses load intensity, unit weight, angle of repose → (a).
• Q5: For isolated footings, 25 mm limit → (b).
• Q6: A = 500 / 200 = 2.5 m² → (c).
• Q7: Pile capacity = end-bearing + skin friction → (b).
• Q8: Unequal settlement leads to cracks in structure → (b).
• Q9: Well foundations are common for bridge piers → (b).
• Q10: qₛ = 450 / 3 = 150 kN/m² → (b).

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🎯 Motivation / Why Practice Matters

In ECET 2026 Civil, questions from Construction Management are usually direct & scoring. Foundation-related questions check your basic soil mechanics + structural judgment. Practicing them improves:

• Speed in formula-based questions.
• Accuracy in conceptual MCQs.
• Confidence in applying fundamentals of construction technology.

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