$S={}^{\text{'}}tan+c$

The major and minor principal stresses at a point in the ground are calculated and found to be

$450$ and $200$kPa respectively $($no shear on these planes$).$

a$.$ Draw the Mohr's circle for this point and compute the max shear stress.

b$.$ Clearly state what plane does this shear stress acts on$.$

c$.$ Calculate, and show on the Mohr diagram, what the stresses are $35$ degrees below the

horizontal plane $({}_N,{}_N).$

Using a dilatometer, the stresses at a point $3\mathrm{.}5ft$ below the surface along a high slope in

Nikiski, Alaska are:

${}_{\text{h}\text{o}\text{r}\text{i}\text{z}}=210psf$

${}_{\text{v}\text{e}\text{r}\text{t}}=375psf$

And the shear on the vertical surface is ${}_{\text{v}\text{e}\text{r}\text{t}}=+75psf$

a$)$ Find the magnitude and directions of the major and minor principal stresses.

b$)$ Find the magnitude and direction of the maximum shear stress.

c$)$ The normal and shear stress acting at a plane inclined $55$ degrees clockwise from the

horizontal $($ie$.$ where this thing appears to have failed!$).$

d$)$ What is the horizontal earth pressure coefficient $(K_0)$ for this soil? $($use the index$)$

e$)$ Estimate the angle of internal friction $()$ for this soil.