Building Design and Construction Handbook - Merritt - Ventech!

TABLE 6.7 Mass and Volume Relationships*
SOIL MECHANICS AND FOUNDATIONS 6.29
Parameter Relationships
Mass
Volume
M MwG Mass of solids (M s) � � � GV� w(1
� n)
1 � w eS
eMsS Mass of water (M ) � � wM � S� V
G
w s w v
Total mass (M) � M � M � M (1 � w)
s w s
MsV Vv
Volume of solids (V s) � � � � V(1 � n) � V � (Vg � V w)
G � 1 � e e
w
MwSVe Volume of water (V ) � � � SV e � SV � V � V
� 1 � e
w s v v g
w
(1 � S)Ve
Volume of gas (V ) � � (1 � S)Ve� V � (V � V ) � V � V
1 � e
g s s w v w
Vn s Ms Ve
Volume of voids (V ) � � V � � � Ve� V � V
1 � n G � 1 � e
v s s
w
V V (1 � e)
s v
Total volume (V) � � � V (1 � e) � V � V � V
1 � n e
*See Fig. 6.7 for definition of terms.
6.3.5 Soil Classification
s s g w
The purpose of soil classification is to provide the geotechnical engineer with a
way to predict the behavior of the soil for engineering projects. There are many
different soil classification systems in use, and only three of the most commonly
used systems will be discussed in this section.
Unified Soil Classification System (USCS). As indicated in Table 6.8, this classification
system separates soils into two main groups: coarse-grained soils (more
than 50% by weight of soil particles retained on No. 200 sieve) and fine-grained
soils (50% or more by weight of soil particles pass the No. 200 sieve).
The coarse-grained soils are divided into gravels and sands. Both gravels and
sands are further subdivided into four secondary groups as indicated in Table 6.8.
The four secondary classifications are based on whether the soil is well graded,
poorly graded, contains silt-sized particles, or contains clay-sized particles. These
data are obtained from a particle size distribution, also known as a ‘‘grain size
curve,’’ which is obtained from laboratory testing (sieve and hydrometer tests).
Figure 6.8 presents examples of grain size curves.
The Atterberg limits are used to classify fine-grained soil, and they are defined
as follows:
Liquid Limit (LL). The water content corresponding to the behavior change
between the liquid and plastic state of a silt or clay. The liquid limit is deter-