Answer:
pre water pressure [tex]= \sigma_1 = 208.76 kN/m2[/tex]
Explanation:
given data:
frictional angle 25°
unconfined xompressive strength qu = 133 kN/m2
for clay, unconfined compressive strenth is cu
[tex]cu =\frac{qu}{2}[/tex]
cu = 133/2 =66.5 kN/m2
cell pressure [tex]\sigma_3[/tex] is zero in uncomfined compressive strenth test
from principle effective stress we have
[tex]\sigma_1 = \sigma_2 tan^{2}(45+ \frac{\theta}{2}) +2cu tan(45+ \frac{\theta}{2})[/tex]
[tex]\sigma_1 = 2cu tan(45+ \frac{\theta}{2})[/tex]
[tex]\sigma_1 = 2*66.5 tan(45+ \frac{25}{2})[/tex]
[tex]\sigma_1 = 208.76 kN/m2[/tex]
as this test is quick test i.e. undrained test therefore
pre water pressure [tex]= \sigma_1 = 208.76 kN/m2[/tex]
