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Vertical/Hori Subgrade Reaction for single pile

Vertical/Hori Subgrade Reaction for single pile

hello everyone,
how to calculate Vertical/Hori Subgrade Reaction for single pile ?
Thank advance.

RE: Vertical/Hori Subgrade Reaction for single pile

Its not something you calculate. It is a property of the soil that is determined from field testing the soil properties and/or load testing in-situ piles.

RE: Vertical/Hori Subgrade Reaction for single pile

@MotorCity, yes.
The soil testing report not included this...
I need this cause I want to design Pile-Cap and Pile.
If have formula or spreadsheet, please share me.

RE: Vertical/Hori Subgrade Reaction for single pile

It is helpful for me.
Thank you 🙏 so much.

E in 2nd of Kh is the same Es?

RE: Vertical/Hori Subgrade Reaction for single pile

First subgrade modulus is not a soil property. Structural engineers need to stop using this for foundation design.

Second, the property you need and should want is Young's Modulus obtained at an appropriate shear strain level. If you are interested in settlement, then that rules out use of "E" estimated by SPT (never should any geotechnical engineer use blow counts to get N, even in sand) and it also rules out CPT
"estimates" because both CPT and SPT completely destroy soil structure and stress history because they shear at strain levels from 10 to over 100 percent. See attached figure.

Third, you need to rely on an in-situ test that tests the soil at an appropriate shear strain for the intended application. For consideration of settlement, typically suitable shear strains are in the range of 0.0001 to 0.001; in this range, both Pressuremeter and flat blade dilatometer testing can be useful. Pressuremeter is good for clays sufficiently stiff to remain open through medium strength rocks. By contrast, the DMT is very appropriate for all sands, cohesive soils, through to soft rock with up to 400 MPa. The lateral Young's modulus is readily obtained from both of these tests.

RE: Vertical/Hori Subgrade Reaction for single pile

Eg1776 - interesting perspective. It sounds all well and good to tell everyone to use DMT or pressuremeter test to determine Young's Modulus (E') however in the real world I think a lot of engineers do use a correlation between N and E'. I have correlations in NZ and it is widely used in the UK too. CIRIA Report 143 'The standard penetration test (SPT): methods and use' gives the correlation of E' = N (MPa). (i.e. for an N of 10, E' would be 10MPa. For cohesive soils E' = 0.9N (MPa). It also gives a correlation for E' from Undrained Shear Strength of E' = 130 x Cu (kPa). I am not saying this is correct and you are wrong, just my two cents.

For most site investigations a boreholes with SPTs are prescribed. U100s would also be prescribed to get undisturbed samples for triaxial or Odeometer tests. DMTs and Pressuremeters are somewhat rare.

Would pressuremeter and DMTs be the 'norm' for testing in you area?

PS - sorry to high jack the thread but couldnt help comment.

RE: Vertical/Hori Subgrade Reaction for single pile

eg1776, nice graph. My experience is that typically, the modulus from the pressuremeter tests is much larger than the unconfined compressive strength tests. As you mentioned, this is based on the strain ranges which is different for both tests.

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