Questions about Hansen Bearing Capacity

[Alexis7]

Hi everyone!

I'm working on a spreadsheet for compute soil bearing capacity according to Hansen's method, and checking my spreadsheet with the examples given at Bowles (5th edition) I have some differences, and I can't understand where is the difference of the results. Also I've been trying to find the codes of the softwares that are used in the textbook, but so far I haven't found anything. Here are my values of q_u, and what it should be according to Bowles textbook (Table 4-6).

D= 0.5 m
B = 0.5 m
L = 2.0 m
γ = 17.06 kN/m³
ϕ = 38.5 (40.75°)
c = 7.8 kPa
q_ult (Bowles- Hansen method): 23.7 kg/cm2
q_ult(My spreadsheet - Hansen Mehtod): 21.3 kg/cm2

Results:

I would really appreciate your help.