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

�o�.•n, the dry den- be computcd as I�y 1.6a 100 ction of soils it is :pute the dry unit iined i[ the volume ecreased by exclu- egree oEsaturatio� : l00 per cent. This ; =ao air roidr. The ir voids, - V. IJ ncom•enient to de- irecdy from meas- ight and total vol- �ly determined in- based on a knowl- tht rolid cont(ifuenlr oed as tituenu, '. 1.8 eal with the rprcific alr G, defin�d as onstituenu, �„ 1.9 LLCR�6� .87 .94 .o-3.1 .2-3.4 .2-3.5 .8 .3t .17 .2 `lht h'an- 3ull. 848, Iling the fPright• Vo6�mc Rr(ationshipn of Soil .A�rega�e Table 1.4 Porosih•� Void Ratio, and Unit \{'cig6t of T��pical Soils in Natural Statc I. 2. 3. 4. 5. 6. 7. 8. 9. 10. I1. Description Uniform sand, loou Uniform sand, dense Mired•grained sand,looso bfirad-grained sand, dense Windbloa•n silt (Ioes�) Glacial till, very mi�ed•grained SoR glacial clay StiR glacial clay Soh �lightly organic clay Soft very organic clay Soft montmorillonitic clay (calcium bentonite) Void �Vamr Porosit� Ratio Contont in) ��) �+�)' Unit �Veight g/cu cm Ib/cu fc Ydb Yui Y� Y�•� 0.�46 0.85 32 1.43 1.89 90 118 0.34 0.51 19 1.75 2.09 109 130 0.40 0.67 25 1.5� 1.99 99 124 0.30 0.43 16 1.86 2.16 116 135 0.50 0.99 21 1.36 l.86 85 116 0.20 O.YS 9 2.I2 2.32 132 14i 0.55 1.2 45 1.22 1.77 76 110 0.3) 0.6 22 I.iO 2.07 106 I29 0.66 1.9 i0 0:93 1.58 58 98 0.75 3.0 I10 0.68 1.43 43 89 0.84 5.2 194 0.43 1.27 27 80 • m= Nater wntent when saturated, in per cent of dry �reight. ° y� � dry unit �reight. `y„� � saturated unit N•eight. wharc y„ is the unit weight of �vater, taken as 1 g/cu cm in the metric s}�stem or 62.5 16/cu ft in the English system. The value of y, or C may be dctermined by test in the laboratory, but it can usually be estimated Nith sufficient accuracy. For routine com- putations, the value ot G for sands may be taken as 2.65. Tesu on a large number of clay soils have indicated that the value of G usually (alls in che range from 2.5 to 2.9 with an acerage value ot about 2.7. Table 1.3 gives the specific gra�•ity oC the most impartant soil constituents. It may be ot assistance in estimating the calue of G for a soil of known mineral composition. Typical values of porosity, �•oid ratio, and unit weight oC various soils are listed in Table 1.4. Denrity of Soil Aggrrgale. Thc behavior of any soil is inftu�nced to a considerablc extcnt by its rclati�•e looseness or dcnsencss. In this rc- spect, ho�.•e�•eq a distinciion is neccssary be- tween coarse-grained cohesionless soils and cohesi�•� matcrials. In a mass o! coarsc- grained soil most of thc gnins couch sc�•crel athcrs in poinbto-point contact and cflbrts 13 [o d�nsify the mass can reduce the �•oid ra[io only through rearrengement or trush- ing of the particles. On the other hand, the densifitation of fine-grained soil, espccially clay, depends on other factors such as co- hesion and the presence of water films on the particle surfates. The �•oid ratio or porosity oE any soil usually does not in itself furnish a direct in- dication ot iu behavior under load or during exca�•ation. Of two coarse-grained soils at the same ��oid ratio, one soil may be in a dense state whereas the other may be loose. Thus, thc relative dansiry of a toarse- grained matcrial is much more significant than the �•oid retio alone. The relati�•e den- sity can bc c�presscd numerically by che drnrily rndrx, le, defined as �mnx - � Dcnsity index, !a = 1.10 �max -�min in ��hich em,x is the ��oid ratio o( the soil in its looscst statc, r is the actual coid ratio, and r,,,i„ is thc ��oid ratio in the dcnsest possible state. Hcncc, la = I.0 for a ccry dense seil and 0 for a vcry loose soil.