Finding the phi angle for layer
Finding the phi angle for layer
(OP)
Hello everyone
I have this problem for Foundation Engineering. When determining the allowable downward capacity, I need to calculate the toe bearing capacity. To calculate it I used the following formula:
q'_t = B*gamma*N_gamma + sigma'_ZD * N_q*
To calculate the N_q* and N_gamma, I need to find the phi angle for each layer. The N_60 count for each layer is given to me. But I'm confused on how do I need to find the phi angle if N60 is given for one layer of soil ?
I have this problem for Foundation Engineering. When determining the allowable downward capacity, I need to calculate the toe bearing capacity. To calculate it I used the following formula:
q'_t = B*gamma*N_gamma + sigma'_ZD * N_q*
To calculate the N_q* and N_gamma, I need to find the phi angle for each layer. The N_60 count for each layer is given to me. But I'm confused on how do I need to find the phi angle if N60 is given for one layer of soil ?





RE: Finding the phi angle for layer
RE: Finding the phi angle for layer
You can use your SPT data and Meyerhof (1956,1976) from page 895 of Bowels 5th edition. This will be a rough guide and should be confirmed against your local code.
Ult capacity = Ap(40N)(Lb/B).......pick the lesser of that and Ap(380N)
Ap - area of pile base
N - N70, you will need to convert your N60 to N70 by using the SPT hammer efficiency
Lb - penetration to bearing stratum
B - width of pile diamater
Note - N is the average Nvalue of 8B above pile toe and 3B below plie toe. Use a conservative average.