194 CHAPTER EIGHT
Characteristics of the soil are computed from(8.32)
(8.33)
(8.34)
(8.35)
(8.36)
Maximum density is found by plotting a density–moisture curve.
Load-Bearing Test
One of the earliest methods for evaluating the in situdeformability of
coarse-grained soils is the small-scale load-bearing test. Data developed
from these tests have been used to provide a scaling factor to express the set-
tlementof a full-size footing from the settlement 1 of a 1-ft^2 (0.0929-m^2 )
plate. This factor / 1 is given as a function of the width Bof the full-size
bearing plate as
(8.37)
From an elastic half-space solution, Escan be expressed from results of a plate
load test in terms of the ratio of bearing pressure to plate settlement kvas
(8.38)
whererepresents Poisson’s ratio, usually considered to range between
0.30 and 0.40. The Esequation assumes that 1 is derived from a rigid, 1-ft
(0.3048-m)-diameter circular plate and that Bis the equivalent diameter of
the bearing area of a full-scale footing. Empirical formulations, such as the
/ 1 equation, may be significantly in error because of the limited footing-
size range used and the large scatter of the database. Furthermore, considera-
tion is not given to variations in the characteristics and stress history of the
bearing soils.
Eskv(1^2 ) /4
4 B/(1B)^2^1
2 B
1 B
2% Compaction100(dry density)
max dry densityDry densityfield density
1 % moisture/100Field density, lb/ft^3 (kg /m^3 )weight of soil, lb (kg)
volume of soil, ft^3 (m^3 )% Moisture100(weight of moist soilweight of dry soil)
weight of dry soilweight of sand filling hole, lb (kg)
density of sand, lb/ft^3 (kg/m^3 )Volume of soil, ft^3 (m^3 )