Laterally loaded pile in liquifiable soil

[MedNeuvo]

I want to analyze the lateral pile capacity using COMP624P in a liquefiable soil. The pile will rest on hard rock, but most of the layers between surface and hard rock are liquefiable layers. The structural engineer wants to tie the pile at the top. I believe I have to model it in two steps. First, analyze the pile only with shear strength of liquefiable layers equals to zero. Then, based on the deflection at the top, provide friction for the tie. If anyone can give me more ideas, that will be of great help. Thanks.

 

[moe333]

This topic has been discussed several times in this forum. Do a thread search.

 

[MedNeuvo]

I searched the thread, but did not get any suitable answer. However, once again, my question is, in liquefiable soil layer below the water table, should we use bouyant unit weight of the soil or just the unit weight of water, taking soil will be water during liquefaction. And providing shear strength parameters, like phi=0 (C is already zero for cohessionless soil)? With shear strength zeo, the pile will have so side friction during liquefaction. I just want to make sure that I am doing right. Please, drop few valuable comments. Thanks.

 

[moe333]

Google this paper on the web. It provides recommendations for your analysis.

Boulanger, R.W. et al (2003), Pile Foundations in Liquefied and Laterally Spreading Ground During Earthquakes: Centrifuge Experiments and Analyses. Department of Civil and Environmental Engineering, University of California at Davis, Report No. UCD/CGM-03/01, September.

 

[dgillette]

Boulanger has a number of research reports you can download. A MAJOR issue is the lateral loads placed on the piles by spreading.

http://cee.engr.ucdavis.edu/faculty/boulanger/

 

[ThingsLearner]

I am not quiet familiar with comp624p but you can model the lateral behavior of the pile using concave-up p-y curves like the ones reported by Scott Ashford.
This is an open research area and the experimental data shows that at large displacements liquefied soil will demonstrate increasing lateral resistance (concave up).
Scott has also presented some mathematical expression for the p-y curves in liquefied sand after finishing Treasure Island experiments.
Neglecting the soil resistance may seem to be conservative BUT in earthquake engineering we do not have such a thing as conservative. so you may want to do both analysis.

Please let me know if you are interested in this approach and need more details.

 

[Gimbli]

LPILE from ENSOFT, INC has the concave curves for liquefied soils as discussed by Thingslearner