# pls provide detail explanations on how to plot the cumulative number of blows/penetration curve. pls provide...

pls provide detail explanations on how to plot the cumulative number of blows/penetration curve.
pls provide detail explanations on how to determine the CBR of the various layers.

Cluil Enginuring Sie Invatgation Dynamie Con Penetro muter Erample bcP teat (byname Co Penetromaur) Ih resuts from Im on a secthon a 1 elown to a cle ptl af aloout he neo labo ratory budel ing parking for shown below: Penetrahon Alo 1Do oo 300 400500 600 00 00q001000 Blows 3 20 22 3 of IG Penetraton-i Cmm) a Plot 4he Cumu latwe number af. blows Penetraton Cuve b) betermin the numbur op layers anal thielene s3 of layer's +he var ous the various layers +e CBR of beter min sub sucpace conelrton su93eateal J bescribe the by e results Avel Memory Log (ceR)

 No. of Blows Cumulative No. of Blows (1) Cumulative Penetration (mm) (2) DCP Penetration/blow (mm)(3) CBR (%) (4) Average DCP Penetration/blow (mm) (5) Average CBR Per Layer (%)(6) Layer Thickness (mm) ( c)(7) Soil Type (d) (8) 0 0 0 0 6.388888889 42.52706595 300mm (Layer 1) Sand 16 16 100 6.25 43.52660775 16 32 200 6.25 43.52660775 15 47 300 6.666666667 40.65635696 3 50 400 33.33333333 7.418518196 41.66666667 5.859806599 Layer 2 (400mm) Clay 2 52 500 50 4.832687417 3 55 600 33.33333333 7.418518196 2 57 700 50 4.832687417 20 77 800 5 55.104708 6.388888889 56.9264908 Layer 3 (300mm) Gravelly Sand 20 97 900 5 55.104708 22 119 1000 4.545454545 60.94537781

Detailed Solutions

1. Since the number of blows per 100 mm penetration is given, cumulatively add the total number of blows for each successive 100 mm penetration, (Refer Column number (1)).

For calculating the DCP Penetration per blow ( Refer column No. (3)), divide the penetration required for 100mm by corresponding number of blows.

For eg. , DCP penetration per blow for 400mm penetration = (400-300)/ 3 = 33.33mm. Now plot the graph as shown in the above chart.

1. For finding the number of layers, identify the slope change of the penetration curve. Every change in slope represents a change in layer type.(Refer Chart)

Thickness of layer is the cumulative penetration (Refer Column (2)) at the bottom of the layer subtracted by the cumulative penetration at the top of the layer.

Calculate the average DCP penetration per blow for each layer (Refer column (5))

1. From the following given equation,

log10CBR = 2.48 – 1.057 log10(DCP Penetration / blow)

The CBR value of each layer can be computed as:

Layer Average CBR = 102.48 – 1.057 log10(Average DCP Penetration per blow (mm) for corresponding layer)

1. The reference book: User Guide to the Dynamic Cone Penetrometer by Office of Minnesota Road Research has been used to correlate the CBR and DCP penetration values with soil type.