Horizontal extent of failure surface for foundation on sand

[YamaT]

Hello

I am having trouble with finding any literature regarding the horizontal extent of a failure surface for a shallow foundation on sand.

I have made a symmetric FEM-model of my foundation to determine its bearing capacity and compare it to lab results along with Terzaghi's solution. However, it appears that the failure surface in Abaqus is extending beyond my domain - or in this case half of the sandbox (it is 0,8 m long). My angle of friction is 47 degrees (I know it is unrealistic for small lab experiments)

The question is how can I determine the horizontal extent of the failure surface as a function of friction angle?... is there a figure that illustrates this?

The attached file illustrates an extended domain (1,1 m long) .. it looks now that it is correct.

 

[YamaT]

Here is a picture of original domain

 

[dcarr82775]

Soil Mechanics by Perloff and Baron has a decent discussion relating to how Terzaghi came up with his equations. The diagrams explain things very well IMO and seems simple enough but it uses a log spiral so (for me anyway) it becomes nasty to calculate.

I have always had an issue with using FEM programs for geotechnical problems. Soils are not homogenous/isotropic, and we simple know to little info about the in-situ conditions to utilize FEM analysis. my two cents anyway.

 

[YamaT]

Perhaps I should rephrase my question...I have actually a more need for results than the theory. Log spirals are OK as long as I can see the extent of failure surface with different friction angles...

 

[dcarr82775]

Can't help you with actual test results. good luck