SOIL VOLUME AND DENSITY RELATIONSHIPS

This cue card is based on chapt. 2 sect. 3 of Foundation Analysis and Design (5th ed) by Joseph E. Bowles (permission to quote from the book has been granted). To understand the cue card, the user should have the book. Comments or questions concerning the cue card should be directed to the developer, Helmut Schmidhofer, on 02 4862 1295 (international replace leading 0 with 61) or email engcomp@gmail.com.

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Given:
**** moisture content in percent, W = 22.5
**** specific gravity of soil grains, GS = 2.6
**** sample mass in grams, WT = 224.0
**** sample volume in cm3, VT = 118

Then:
wet unit mass in g/cm3, RHO_WET = WT/VT := 1.8983
wet unit weight in kN/m3, GAM_WET = RHO_WET*9.807 := 18.6167
dry unit weight, eq. (2-9), GAM_DRY = GAM_WET/(1+W/100) := 15.1973
unit mass of solids in g/cm3, WS = RHO_WET/(1+W/100) := 1.5496
unit volume of solids, VS = WS/GS := 0.596
unit volume of voids, VV = 1-VS := 0.404
unit mass of water WW = RHO_WET-RHO_WET/(1+W/100) := 0.3487
unit volume of water, VW = WW := 0.3487
degree of saturation in percent, S = 100*VW/VV := 86.3119
dry bulk specific gravity GB = GAM_DRY/9.807 := 1.5496

The following templates for equations 2-1 to 2-12 may be used in isolation if the required variables are given:

Eq. (2-1) Void ratio E:
**** volume of voids in cm3, VV = .404
**** volume of solids in cm3, VS = .596
Void ratio E = VV/VS := 0.6779

Eq. (2-2) Porosity N:
**** volume of voids in cm3, VV = .404
**** total volume in cm3, VT = 1.0
Porosity N = VV/VT := 0.404

Eq. (2-3) Water content W:
**** mass of water in grams, WW = .3487
**** mass of solids in grams, WS = 1.5496
Water content in percent, W = 100*WW/WS := 22.5026

Eq. (2-4) Unit weight GAMMA:
**** weight of sample in g/cm3, WT = 224
**** volume of sample in cm3, VT = 118.0
Unit weight in kN/m3, GAMMA = 9.807*WT/VT := 18.6167

Eq. (2-5) Degree of saturation S:
**** volume of water in cm3, VW = .3487
**** volume of voids in cm3, VV = .404
Saturation in percent, S = 100*VW/VV := 86.3119

Eq. (2-6) Specific gravity G:
**** mass of solids in grams, WS = 1.5496
**** volume of solids in cm3, VS = .596
Specific gravity of soil grains, GS = WS/VS := 2.6

Eq. (2-7) Porosity N from void ratio E:
**** void ratio, E = .6779
Porosity, N = E/(1+E) := 0.404

Eq. (2-8) Void ratio E from porosity N:
**** porosity, N = .404
Void ratio, E = N/(1-N) := 0.6779

Eq. (2-9) Dry unit weight:
**** wet unit weight in kN/m3, GAM_WET = 18.6167
**** moisture content in percent, W = 22.5
Dry unit weight, GAM_DRY = GAM_WET/(1+W/100) := 15.1973

Eq. (2-10) Void ratio E:
**** moisture content in percent, W = 22.5
**** degree of saturation in percent, S = 86.3
**** specific gravity of soil grains, GS = 2.6
Void ratio, E = GS*W/S := 0.6779

Eq. (2-11) Dry unit weight:
**** moisture content in percent, W = 22.5
**** degree of saturation in percent, S = 86.3
**** specific gravity of soil grains, GS = 2.6
**** unit weight of water in kN/m3, GAM_W = 9.807
Dry unit weight, GAM_DRY = GAM_W*GS/(1+GS*W/S) := 15.1968

Eq. (2-12) Wet unit weight:
**** moisture content in percent, W = 22.5
**** degree of saturation in percent, S = 86.3
**** specific gravity of soil grains, GS = 2.6
**** unit weight of water in kN/m3, GAM_W = 9.807
Wet unit weight, GAM_WET = GAM_W*GS*(1+W/100)/(1+GS*W/S) := 18.6161