Dilatometer test results obtained as part of a subsurface investigation for a planned construction project indicated the following data for one of the tested locations (note the dilatometer instrument...

Dilatometer test results obtained as part of a subsurface investigation for a planned construction project indicated the following data for one of the tested locations (note the dilatometer instrument gauge indicates pressure in bars):

p₀
= 3.0 bars (300 kPa),

p₁
= 12.76 bars 9(1276 kPa),

p₂
= u = 0.20 bars 999(20 kPa).

that the soil is sand. The soil overburden pressure, , at the test depth is 53 kPa (0.53 bar). From this information, estimate the angle of internal friction f for the sand at the test depth. (To determine E_D, ID, K_D, etc., perform calculations using bar as the unit for pressure.)