222 W MARINE VIEW DR 2016-01-01 MF Import

12 l�/den�ificntion and GasJificaiion of Soils and Rocks some fine-graincd soils above it are in a sawratcd condition. Ho�.•c�•cq thc voids of most soils aboee the water table are filled partly with water and partly ��'ith air. Even some submerged soils ha�•e a significant air or gas content. The drgrre oJ ratura(ion is dc- fined as Degree of saturation, S,��fo) = 100VN/V, S.4 Thus, at a degree ot saturation of ]00 per cent all of the �•oid space is filled with watcr. The weight per unit ot volume or unit weighl y is one oE the most important physi- cal properties of a soil. It must be knawn, for example, before computations oC earth pres- sure or overburden pressure can be made. By definition Unit ti�eight, y= ft'/V 1.5 wherein iV is che total ti•eight of ehe soil in- cluding the soil moisture and V is the total volume. It is com�enient to indicate particu- lar values of unit N•eight by means of sub- scripts. If the soil is completely saturated, that is, if V� s 0, izs �nit ��eight is desig- nated by y„�. I( the soil is ocen-dry, iu unit weight is denoted by ya, designated as dry unit w�ight or dry drruity, and is defined as Dry unit weight, y� = W,/V l.b I( thc ��atcr wntent is known, the dry dcn- sity o( a moist sample can be computcd as ioorv l�y 1.6a Ya = ��00 �- w)V 100 w In studics of the compaction of soils it is sometimes usctul to compute the dry unit �eeight that �could be obtained if the volume ot a moist sample were decreased by exclu- sion o[ the air until the degree of saturation of the sam?le just rcached 100 per cent. This condition is designated as zcro air uoids. The corresponding unit �reight, Dry unit weight at zero air voids, i1r. 1.7 1'. _ V. i- V� In practicq it is oltrn inconvenirn� to de- termine the value oC y directly from meas- uremenu oC the total H�eight and total vol- ume. It is more commonly determined in- dirady by computation based on a knowl- edge of the unil wtight of the tolid constilutn(t y,. This quantity is defincd as Unit N•eight of solid constituenu, 'Y� = Tfr.�v� 1.8 It is often preferable to deal with the sprcific grauily oJ fht tolid ronrtilurnfr C� defined as Specific gravity of solid constitu�nu, G = 'r./Y. 1.9 Table 1.3 Specific Grarity of �fost Important Soil Conatituents• GyPn� 2.32 Dolomite 2.87 D4ontmorillanite� 2.65-2.80 Aragonite 2•94 Orthoclau 2.56 Biocice 3.o-9 1 Kao6nite 2.6 .�lugite 9.2-3.4 I��i�e 2,8 Hornblende 8.2-3.5 Chlorite 2.6-3.0 Limonitt 3.8 Quarts 2.66 Hcmatite,hydrous 4.3t Tale 2.: \Sagnetite 5.17 Calcite 2.72 Hematite 5.2 Dfusrnvite 2 •8-2 • 9 • From E. S. Lanen and H. &rman, Tht bliaoirofit Ddnminafion of /he Non- pyaque Alinaalt, setond edition, U. S, Department of the Interior, Bull. 848, Washington, 1934. b From R. E. Olson and G. Mcsri (19i0). "Tfechanismt CoNrolling the Comprcuibilicy ot Claye;' ASCE J. Soi1.4lrrh., A5, Nu. Srf6. Table 1.4 P. Des �, Uniform sarn 2, Uniform sarn 3. TSixed-grairo 4. Mixed-grain� 5. Windblo�.�n : 6. Clacial till, � 7. Soft glacial c S. StiR glacial � 9. SoR alightly 10. SaR very orQ 11. Soft montmc (caleium ber • w s water con s y� = dry unit � ' y.�� i sBtUfate where y„ is the as l g/cu cm i Ib/cu ft in the y, or C may b laboratory, but with sufficient putations, the • taken as 2.65. clay soils have usually falls in t an average val Table 1.8 gi� most importan• of auistance in a soil of known Typical valu unit weight of Table 1.4. Drntily oJSoil A soil is in8uence its relative ]oos spect, ho�aa�•ee twecn coarse•g cohesi�•e mate: graincd soil mc others in point