TM 5-818-1 / AFM 88-3, Chap. 7
CHAPTER 9
SELECTION OF FOUNDATION TYPE
for different subsoil conditions are summarized in table
9-1.
Foundation - selection considerations.
9-1.
Selection of an appropriate foundation depends upon the
a. Some foundation alternatives may not be
structure function, soil and groundwater conditions,
initially obvious. For example, preliminary plans may not
construction schedules, construction economy, value of
provide for a basement, but when cost studies show that
basement area, and other factors. On the basis of
a basement permits a floating foundation that reduces
preliminary information concerning the purpose of the
consolidation settlements at little or no increase in
structure, foundation loads, and subsurface soil
construction cost, or even at a cost reduction, the value
conditions, evaluate alternative types of foundations for
of a basement may be substantial. Benefits of basement
the bearing capacity and total and differential
areas include needed garage space, office or stor-
settlements.
Some
foundation
alternatives
Table 9-1. Foundation Possibilities for Different Subsoil Conditions
Foundation Possibilities
Subsoil Conditions
Light, Flexible Structure
Heavy, Rigid Structure
Deep compact or
Footing foundations
1. Footing foundations
stiff deposit
2. Shallow mat
Deep compressible
1. Footing foundations
1. Deep mat with possi-
strata
on compacted granular
ble rigid construc-
a
tion in basement
zone
a
2. Long piles or cais-
2. Shallow mat
3. Friction piles
sions to by-pass
3. Friction piles
Soft or loose
1. Bearing piles or
1. Bearing piles or
strata overly-
piers
piers
ing firm strata
2. Footing foundations
2. Deep mat
on compacted granular
a
zone
2
3. Shallow mat
a
Compact or stiff
1. Footing foundations
1. Deep mat (floating
layer overlyinga
type)
a
2 Long piles or cais-
soft deposit
2. Shallow mat
sons to by-pass soft
deposit
a
1. Deep mat
Alternating soft
1. Footing foundations
a
2. Piles or caissons to
and stiff
2. Shallow mat
layers
underlying firm
stratum to provide
satisfactory
foundation
a
Consider possible advantages of site preloading, with and without vertical sand drains to accelerate
(Courtesy of L. J. Goodman and R. H. Karol. Theory and Practice of Foundation Engineering,
1968, p 312. Reprinted by permission of Macmillan Company, Inc New York.)
9-1
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