 # Classify the following soils using the Unified soil classification system. Give the group symbols and the group names. ### Principles of Geotechnical Enginee...

9th Edition
Braja M. Das + 1 other
Publisher: Cengage Learning
ISBN: 9781305970939 ### Principles of Geotechnical Enginee...

9th Edition
Braja M. Das + 1 other
Publisher: Cengage Learning
ISBN: 9781305970939

#### Solutions

Chapter
Section
Chapter 5, Problem 5.9P
Textbook Problem

## Classify the following soils using the Unified soil classification system. Give the group symbols and the group names. Expert Solution
To determine

Find the classification of the given soil using unified soil classification system and give the group symbols and group names.

### Explanation of Solution

Calculation:

For soil 1:

The plasticity index (PI) is 21.

Determine the coarse fraction.

Coarsefraction=100percentpassingonNo.200seive (1)

Substitute 30 % for percent retained on No.200 sieve in Equation (1).

Coarsefraction=10030=70%

Determine the gravel fraction.

Gravelfraction=100percentpassingonNo.4seive (2)

Substitute 70 % for percent passing No.4 sieve in Equation (2).

Gravelfraction=10070=30%

Determine the sand fraction using the relation.

Sandfraction=PercentofcoarsefractionPercentofgravelfraction (3)

Substitute 70 % for percent of coarse fraction 30 % for percent of coarse fraction in Equation (3).

Sandfraction=7030=40%

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as SC_.

Provide the group name of soil as shown below.

The gravel fraction 30% is 15%.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as clayey sand with gravel for the group of SC and gravel fraction of 15%.

Thus, the classification of soil 1 using unified soil classification system is Clayeysand with gravel_.

For soil 2:

The plasticity index (PI) is 22.

Determine the coarse fraction as shown below.

Substitute 20 % for percent retained on No.200 sieve in Equation (1).

Coarsefraction=10020=80%

Determine the gravel fraction as shown below.

Substitute 48 % for percent passing No.4 sieve in Equation (2).

Gravelfraction=10048=52%

Determine the sand fraction using the relation.

Substitute 80 % for percent of coarse fraction 52 % for percent of coarse fraction in Equation (3).

Sandfraction=8052=28%

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as GC_.

Provide the group name of soil as shown below.

The sand fraction 28% is 15%.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as clayey gravel with sand for the group of GC and sand fraction of 15%.

Thus, the classification of soil 2 using unified soil classification system is Clayeygravel with sand_.

For soil 3:

The plasticity index (PI) is 28.

Determine the coarse fraction as shown below.

Substitute 70 % for percent retained on No.200 sieve in Equation (1).

Coarsefraction=10070=30%

Determine the gravel fraction as shown below.

Substitute 95 % for percent passing No.4 sieve in Equation (2).

Gravelfraction=10095=5%

Determine the sand fraction using the relation.

Substitute 30 % for percent of coarse fraction 5 % for percent of coarse fraction in Equation (3).

Sandfraction=305=25%

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as CH_.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as sandy fat clay for the group of CH, 30% plus No.200, %sand%gravel, and <15%gravel.

Thus, the classification of soil 3 using unified soil classification system is Sandyfat clay_.

For soil 4:

The plasticity index (PI) is 19.

Determine the coarse fraction as shown below.

Substitute 82 % for percent retained on No.200 sieve in Equation (1).

Coarsefraction=10082=18%

Determine the gravel fraction as shown below.

Substitute 100 % for percent passing No.4 sieve in Equation (2).

Gravelfraction=100100=0

Determine the sand fraction using the relation.

Substitute 18 % for percent of coarse fraction 0 for percent of coarse fraction in Equation (3).

Sandfraction=180=18%

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as CL_.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as lean clay with sand for the group of CL.

Thus, the classification of soil 4 using unified soil classification system is Lean clay with sand_.

For soil 5:

The plasticity index (PI) is 21.

Determine the coarse fraction as shown below.

Substitute 74 % for percent retained on No.200 sieve in Equation (1).

Coarsefraction=10072=26%

Determine the gravel fraction as shown below.

Substitute 100 % for percent passing No.4 sieve in Equation (2).

Gravelfraction=100100=0

Determine the sand fraction using the relation.

Substitute 26 % for percent of coarse fraction 0 for percent of coarse fraction in Equation (3).

Sandfraction=260=26%

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as CL_.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as lean clay with sand for the group of CL.

Thus, the classification of soil 5 using unified soil classification system is Lean clay with sand_.

For soil 6:

The plasticity index (PI) is 18.

Determine the coarse fraction as shown below.

Substitute 26 % for percent retained on No.200 sieve in Equation (1).

Coarsefraction=10026=74%

Determine the gravel fraction as shown below.

Substitute 87 % for percent passing No.4 sieve in Equation (2).

Gravelfraction=10087=13%

Determine the sand fraction using the relation.

Substitute 74 % for percent of coarse fraction 13 % for percent of coarse fraction in Equation (3).

Sandfraction=7413=61%

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as GC_.

Provide the group name of soil as shown below.

The gravel fraction 13% is <15%

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