Civil - Foundation Engineering - Shallow Foundation
Shallow
Foundation
1. What are components of total foundation
settlement?
Elastic settlement, consolidation settlement,
secondary consolidation settlement
2. What are the types of shear failure?
General shear failure, local shear failure, punching
shear failure
3. What are assumptions in Terzaghi's bearing
capacity theory?
- the base of the footing is rough
- the load on footing is vertical and uniformly
distributed
- the load on footing is vertical and uniformly
distributed
4. List out the methods of computing elastic
settlements?
based on the theory of elasticity, Pressure meter
method, Janhu -Bjerram method,
Schmentmann's method
5. What are the limitation of Terzaghi's analysis?
- As the soil compresses, pi changes slight down
ward movement of footing may
not develop fully the plastic zones
- Error due to assumption that the resultant passive
pressure consists of three
components is small
6. Define ultimate bearing capacity?
Gross pressure at the base of the foundation at
which the soil fails in shear is called ultimate bearing capacity.
7. Define net ultimate bearing capacity ?
Net pressure increase in pressure at the base of the
foundation that causes failure in shear, is called as net ultimate bearing
capacity
8. Define allowable bearing capacity?
It is the net loading intensity at which neither the
soil fails in shear nor there is excessive settlement detrimental to the
structure
9. Write the expression for correction due to
dilatancy submergence?
Ne = 15 + ( No-15 )
10.What are the requirements for a stable
foundation?
-must be safe from failure
-must be properly located
-must not settle or deflect sufficiently to damage
the structure or impair its usefulness.
11. What are the factors which depends depth?
Type of soil, size of structure, magnitude of loads,
environmental conditions, etc
12 .Define net pressure intensity ?
It is the excess pressure, of the gross pressure
after the construction of the structure
and the original overburden pressure.
13. What are the zones used in the Terzaghi's
bearing capacity analysis for dividing the failure envelope of the soil.?
Elastic equilibrium zone, Radial Stress zone,
plastic zone
14. Write the ultimate bearing capacity equation for
the general shear failure of soil in
Terzaghi's analysis for a strip footing.
qu = c Nc + ?DNq + 0.5 ?B N?
15. Define Shallow foundation.
If the depth of the foundation is less than its
breadth, such foundation is known as shallow foundation.
17. Write down the equation for estimating the
elastic settlement based on the theory of elasticity.?
18. When will the total settlement be completed in
the case of cohesion-less soil?
Once the construction is over, the total settlement
is assumed to be completed.
19. Define differential settlement
If any two points of the foundation base experiences
different settlements then
such settlement is known as differential settlement.
20. What type of shear failure of soil is more
likely to happen in the case of very dense soil?
usually punching shear failure and local shear
failure may also be possible.
21. Write the ultimate bearing capacity equation for
the general shear failure of soil in
Terzaghi's analysis for a square footing.
qu = 1.3 cNc + ?D Nq + 0.4 ?B N?
22. When will the Consolidation settlement get
completed?
In the case of cohesion-less soil, the consolidation
settlement gets completed once the
construction is over. But In the case of cohesive soil, the
consolidationsettlement takes place for several years.
24. Define Deep foundation
If the depth of the foundation is equal to or
greater than the breadth of the foundation such foundation is called as deep
foundation.
25. For which type of foundation, Terzaghi's bearing
capacity equation is applicable. Why?
Shallow foundation only. Because the effect of the
depth is not considered.