Equations for soil properties using STP N-values
Equations for soil properties using STP N-values
(OP)
I am trying to find equations for soil strength, soil compressibility, foundation bearing capacity, foundation settlement, and liquefaction potential using STP N-values. I would be grateful for any information you have - even if you just have a reference to a good website or book containing these.
Thank You,
pmhawkes
Thank You,
pmhawkes





RE: Equations for soil properties using STP N-values
There are some equations that have the relationship between SPT-N values and settlement.
(Meyerhof)
Se=4*q/N for B<=4 ft
Se=6*q/N*((B/(B+1))^2 for B>4 ft
q: intensity of applied load, kip/ft^2
B: width of footing, ft
Se: settlement, in
(Bowles)
Se=2.5*q/N for B<=4 ft
Se=4*q/N*((B/(B+1))^2 for B>4 ft
(Meyerhof) for shallow foundations
for sand and gravel
Se=q*(B)^0.5/(2*N)
for silty sand
Se=q*(B)^0.5/(N)
Se: settlement,in
q:intensity of the applied load (tons/ft^2)
B: width of foundation, in
I also have some relations about stress-strain modulus by SPT. I may send them if it is necessary for you.
RE: Equations for soil properties using STP N-values
-Virginia Polytechnich Institute and State University
The Charles E. Via, Jr.
Depatment of Civil and Environmental Engineering
Center for Geotechnical Practice and Research
1)Performance and Use of the Standard Penetration Test in Geotechnical Engineering Practice by
J. McGregor and J.M.Duncan
2)Shear Strength Correlations for Geotechnical Engineering by J.M. Duncan, R.C. Horz, T.L. Yang
-Manual of Estimating Soil Properties for Foundation Design
by Kulhawy and Mayne
Electric Power Research Institute, Palo Alto California
-Foundation Analysis and Design by J. Bowles
fifth edition
-Principles of Foundation Engineering by B. Das
RE: Equations for soil properties using STP N-values
The equations do not address soil expansion and hydrconsolidation, and zonal soil variations which are factors that cause most foundation distress.
RE: Equations for soil properties using STP N-values
RE: Equations for soil properties using STP N-values
RE: Equations for soil properties using STP N-values
For all of the noted correlations, I would caution that most are very coarse. Also, be aware of the difference between N-values using the older type manual hammers (safety hammer with cathead) and the newer autohammers. Expect higher blow counts for a given soil strength with a manual hammer because those hammers are generally less efficient. Most correlations were developed using manual hammer data.