A brief description of foundation failures and their possible preventive and remedial measures.

1. Review of Causes of Foundation
Failures and Their Possible
Preventive and Remedial
Measures
by
Dr. Amit Srivastava
Associate Professor, Department of Civil & Environmental Engineering
The NorthCap University, HUDA Sector 23-A Gurgaon - 122017.

2. Contents
I. Introduction
II. Load transfer failures
III. Drag down and heave
IV. Collapsible soils
V. Lateral loads
VI. Construction error
VII. Unequal support

3. Contents
VIII.Water level fluctuation
IX. Earthquake
X. Vibration effect
XI. Foundation failure due to landslide/ slope instability
XII. Foundation failure due to uplift
XIII.Conclusion
Contents

4.  Foundations of engineering constructions are systems that act
like interface elements to transmit the loads from superstructure
to, and into, the underlying soil or rock over a wider area at
reduced pressure.
 Engineering structures despite being constructed with
adequate strength and safety measures do fail or collapse.
 “Failure is an unacceptable difference between expected and
observed performance.” – Council of Forensic Engineering,
ASCE
Introduction

5.  The objective of foundation is to transfer the load of
superstructure to the foundation soil on a wider area.
 The uncertainties for which factor of safety is provided in
geotechnical design include (a) the natural heterogeneity or
inherent variability (b) measurement error, and (c) model
transformation uncertainty.
 Classic examples of Bearing capacity failures: Transcona
Grain elevator in 1913 and Fargo Grain Elevator in 1955.
Load transfer failures

6. Figure 1. East side of Transcona elevator following foundation failure
Transcona elevator

7. • Under such circumstances, the most commonly
adopted remedial measure to rectify the problem is
underpinning.
• Underpinning is accomplished by extending the
foundation in depth or width so that it either rests on
a more supportive soil stratum or distributes its load
across a greater area.
• Use of steel piers, helical anchors and micro piles
are common methods in underpinning.
Preventive measures and remedies

8. Figure 2. Foundation Underpinning by hydraulic jacking and transfers
loads to screw foundations installed into stable strata

9. • In plastic soils, new settlements (drag down) are often
accompanied by upward movements and heave some
distance away.
• In swelling and shrinking soils, hot dry wind and intense heat
will often cause the soil to shrink beneath the foundation.
• Uneven saturation of the soil around foundation (located in
expansive soils) can cause the soil to heave as it expands
and contracts after drying.
• Similar problem of heave and contraction is observed when
foundation is placed in extremely cold condition (below
freezing point).
Drag down and heave

10. Figure 3. Pictorial representation of structural damage caused
by drag down and heave
Types of settlement

11. Damages due to expansive soils

12. (i) Soil stabilization with lime, lime-fly ash, Portland cement, etc.
(ii) Control of soil moisture using plastic fabric underneath the
foundation,
(iii) A thin coat of bitumen will drastically reduce the shear-force between
the pile surface and the soil and reduce the negative skin friction,
(iv) Ignoring active zone of expansion and contraction by placing footing
at deeper depth or providing pile/ belled piers,
(v) Heavy structure to overcome swell pressure,
(vi) Ice adhesion and resulting uplift can be avoided by using granular
backfill around the foundation walls or footing pedestals
Preventive measures and remedies

13. • They are deposits of fine grained particles transported by wind
and are characterized by constituent parts with an open packing
arrangement, which forms a meta-stable state that can collapse to
form a closer packed, more stable structure of significantly
reduced volume.
• Collapse in such deposits can be triggered by either
increasing the load on the soil or by wetting it.
• A collapse condition can lead to structure failure, landslides
(depending on the topography), and tsunamis (if the soil
collapses into a body of water).
COLLAPSIBLE SOILS

14. A ‘loess avalanche’ in Shanxi, China which killed 23
people due to structural & foundation failure of small
houses on the slope & at the foot.
Other Failures
Collapsible Soil: LOESS

15. Figure 6. Collapse of the soil in The terraces, Glenwood, Colorado was
causing settlement of the concrete retaining-wall foundations
Collapsible Soil: LOESS

16. • By keeping a check on the structural design, i.e., loads and
foundation selection (mat foundations minimize the risk of
differential settlements)
• Landscape irrigation should be restricted or eliminated, excellent
drainage facilities should be underlain with an impermeable liner
to prevent water from seeping into the soil
• Popular ground modification treatments for such soils include pre-
wetting of the soil, dynamic compaction, Vibro-floatation, Vibro-
compaction, Stone/cement columns, treating the soil with calcium
chloride and/or sodium silicate solutions in order to introduce
cementing that is insoluble, etc.
Preventive measures and remedies

17. • During an earthquake the foundation of the building moves with
the ground and the superstructure and its contents shake and
vibrate in an irregular manner due to the inertia of their masses
(weight).
• Damage to foundations & structures may result from different
seismic effects: (i) Ground failures (or instabilities due to ground
failures), (ii) Vibrations transmitted from the ground to the
structure, (iii) Ground cracking, (iv) Liquefaction, (v) Ground
lurching, (vi) Differential settlement, (vii) Lateral spreading, and
(viii) Landslides.
Failure due to Earthquake

18. • Lateral movement in soil is possible when there is removal of
existing side support adjacent to a building. There is excessive
overburden on backfill or lateral thrust on the backside of a
retaining wall
• Lateral movement is also observed during earthquake when
structure fails due to lateral movement of soil beneath the
foundation following liquefaction
• Classic examples of such failures are: (a) major damage to
thousands of buildings in Niigata, Japan during the 1964
earthquake, (b) Failure of Lower San Fernando dam which
suffered an underwater slide during the San Fernando
earthquake, 1971.
Earthquake & Liquefaction

19. Figure 7. (a) Building Failure during 1964 Niigata, Japan Earthquake, (b) Failure of lower
San Fernando dam in 1971 (c) Retaining wall failure (d) Failure of Showa bridge
during 1964 Niigata earthquake in Japan
Earthquake & Liquefaction

20. Figure 13. Typical example of overturning of a building due to liquefaction of
the foundation soil during the Kocaeli earthquake, Turkey, August 17, 1999,
Magnitude 7.4

21. Liquefaction mitigation measures
(i) Soil Improvement Options
(a) Densification, Deep Dynamic Compaction
(b) Hardening Technique, Grouting,
(ii) Structural Option, Piles or Caissons extending below
the liquefiable soil
(iii) Quality Assurance , in taking mitigation measures

22. (i) Proper planning of Subsurface Investigation,
(ii) Analysis and Design and
(iii) Construction Control and Supervision.
(iv) For small scale damages underpinning of
structures is suggested.
Additional measures and remedies

23. • There are two common sources of construction errors,
i.e.,
(I) Temporary protection measures (Error relating to
temporary shoring, bracings and temporary coffer dams),
(II) Foundation work itself.
Construction error

24. Foundation not aligned properly
Punching failure of foundation Lack of proper investigation
Few cases indicating major Construction failure

25. Figure 9. (a) apartment building was constructed, (b) it was decided for an
underground garage to be dug out. The excavated soil was piled up on the other
side of the building (c) Final failure of building
•This paper presents a classic case of poor construction
practice due to which foundation failure of a building in
Shanghai, China took place
Construction error

26. • There is no remedy for such massive failures but definitely
preventive measures in terms of “supported excavation
system” for “deep excavation problems” can be adopted to
avoid such failures.
• Soil nailing is the latest and most widely used technique for
supporting the vertical excavation near an existing building.
• A classic application of soil nailing technique is reported in
which soil nail support of excavation system for the embassy
of the Peoples republic of China in the United States was
carried out.
Preventive measures and remedies

27. Figure 10. (a) Design details of soil nail wall section (view
from E) (b) work executed for supporting vertical excavation
using soil nailing technique
Soil Nailing Technique

28. • Footing resting on different type of soil, different bearing
capacity and unequal load distribution will result in the
unequal settlement or what we call as differential settlement.
• The Tower of Pisa in Italy is a classic case study.
Unequal support

29. Figure 11. Different strategies applied to prevent the tower from
collapse

30. • Rise in GWT reduces the bearing capacity of the soil and on
the other hand rapid fall in the GWT causes ground
subsidence or formation of sinkholes due to increased
overburden effective stress value.
• Formation of sinkhole is another major cause of foundation
failure due to increased water usage, altered drainage
pathways, overloaded ground surface, and redistributed soil.
• According to the Federal Emergency Management Agency,
the insurance claims for damages as a result of sinkholes has
increased 120% from 1987 to 1991, costing nearly $100
million.
Water level fluctuation

31. Figure 12: Formation of sinkhole due to ground water table
fluctuation

32. • Construction activities such as blasting, pile driving, dynamic
compaction of loose soil, and operation of heavy construction
equipment induce ground and structure vibrations.
• Ground vibrations from construction sources may affect adjacent
and remote structures in three major ways, i.e.,
(I) structure vibration with/without the effect of resonance
structure responses,
(II) dynamic settlement due to soil densification and liquefaction,
(III) pile driving and accumulated effects of repeated dynamic
loads.
Vibration effect

33. • Monitoring and control of ground and structure vibrations
provide the rationale to select measures for prevention or
mitigation of vibration problems, and settlement/damage
hazards. Active or passive isolation systems are adopted in
this regard.
Preventive and remedial measures

34. • Foundation failure due to rapid movement of landmass over a
slope results when a natural or man-made slope on which
structure exists becomes unstable.
• The major causes of slope instability/ landslide can be
identified as (i) Steep slope, (ii) Groundwater Table Changes /
heavy rainfall, (iii) Earthquakes and other vibrations, and, (iv)
removal of the toe of a slope or loading the head of a slope
Foundation failure: slope instability

35. Figure 14. Foundation failure of existing facility due to landslide/
slope instability

36. • Modifying the geometry of the slope,
• Controlling the groundwater,
• Constructing tie backs,
• Spreading rock nets,
• Providing proper drainage system,
• Provision of retaining walls, etc.
• Soil nailing Technique
Preventive and remedial measures

37. • One of the major causes of foundation failure due to uplift is
presence of expansive soil beneath the foundation.
• Swelling clays derived from residual soils can exert uplift
pressures, which can do considerable damage to lightly-
loaded or wood-frame structures.
• In case of pile foundations that are used to resist the uplift
forces due to wind loads, such as, in transmission line towers,
high rise buildings, chimney, etc., the available uplift
resistance of the soil becomes the one of the most decisive
factor in defining the stability of foundation.
Foundation failure due to uplift

38. • The paper reviewed and discussed the various causes of
foundation failure as well as their possible preventive or
remedial measures through case studies.
• The work will be useful for practicing engineers in identifying
the potential foundation problem in advance and taking
necessary and appropriate action for mitigation purpose.
Conclusion

39. THANK YOU!