1、The relative density of sands and gravels only maybe determined by the standard penetration test.A scale in terms of N-values !text deleted“ (seeBS EN ISO 22476-3) is as follows.Term SPT N-values, blows/300 mmpenetration Very loose 0 4 Loose 4 10 Medium dense 10 30 Dense 30 50 Very dense 50 Where me
2、asurements of the undrained shear strength are made in the field using a field or handvane, or in the laboratory by triaxial test, anundrained strength can also be given on the fieldrecord where required or appropriate using thescale below:Term based on measurement from BS EN ISO 14688-2:2004, 5.3,
3、Table 5 Undrained strength classification definition cu, in kPaExtremely low 200 mm) material is very coarse !(63 mm)“ COBBLES Over 50 % is of cobble size !(200 mm to 63 mm)“ Finer material (coarse and fine soil) with asecondary very coarse fraction should be describedin accordance with BS EN ISO 14
4、688-2:2004Table 1. Percentages are approximate visualestimates in a field description and should only betaken as a subjective guide.“Term Composition BOULDERS (orCOBBLES) with a little finer materiala) Up to 5 % finer material BOULDERS (orCOBBLES) with somefinermateriala) 5 % to 20 % finer material
5、BOULDERS (orCOBBLES) with muchfinermateriala) 20 % to 50 % finer material The appropriate terms are used before the principal soil type. Further details should be provided at theend of the main description, after a full stop forclarity, e.g. Medium dense brown very gravellycoarse SAND. Gravel is sub
6、angular fine andmedium of sandstone and mudstone.Term Principalsoil type Approximateproportionofsecondaryconstituentslightly sandy or gravelly sandy or gravelly very sandy or gravelly SAND or GRAVEL Up to 5 %5 % to 20 % Over 20 % SAND and GRAVEL About equal proportions Term Principal soil type Appro
7、ximate proportion ofsecondary constituent Coarse soil Coarse and/orfile soil slightly clayey or silty and/or sandy or gravelly SAND 20 %a) very sandy or gravelly SILT 65 %b) sandy and/or gravelly or 35 % 65 % slightly sandy and/or gravelly CLAYc) 35 % a) Or described as fine soil depending on assess
8、ed engineering behaviour. b) Or described as coarse soil depending on assessed engineering behaviour. !c) Can be silty CLAY or clayey SILT. “ window frames, garden refuse, newspapers (1964).Dense brown sandy GRAVEL with occasional tiles,wire, glass, tyres (MADE GROUND).“Soft grey sandy CLAY. Rare gr
9、avel size brick fragments (MADE GROUND).Firm yellow brown slightly sandy CLAY with clods(up to 200 mm) of firm to stiff orange CLAY(EMBANKMENT FILL).Details are given in !column 8 of Table 13, which is developed from BS EN ISO 14689-1:2003“. The colour given should be the overall impression of the s
10、tratum. Strata with more than one distinct colour may be described, for example, as mottled, but strata with more than three distinct colours should normally be described as multicoloured. Colour changes due to oxidation or desiccation, for example, should be noted. For more detailed descriptions, colour charts such as those based on the system of Munsell may be used 174 175. Consistency of colour description is usually more important than absolute accuracy, and the use of reference samples
