Computation of the Initial Critical Pressure Based on the Hardening Soil Criterion for the Foundation Soil

computation of THE initial critical pressure BASED ON THE hardening soil criterion for THE foundation soil

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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computation of THE initial critical pressure BASED ON THE hardening soil criterion for THE foundation soil Authors:Anghel stanaciuIrina lunguFlorin bejan

Presenter:Florin Bejan

This paper approaches the determination of the initial critical pressure for continuous foundations, with PLAXIS2D software, for the 2D strain conditions and two constitutive models: the Mohr-Coulombs (MC) model and the Hardening Soil (HS) model. New values for the N1, N2 and N3 coefficients are obtained applying Stancius algorithm and using the initial critical pressure values obtained from PLAXIS2D software.

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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pcr.ul.pcr.in.

P

PLASTIC DOMAINpl

Bearing capacity initial critical pressureultimate critical pressurefailure

ELASTIC DOMAINs [cm]p [kPa]

appearance of plastic zones

compression settlement curve

http://www.nouapietre.ro/fundatii.html

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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BEARING CAPACITY

CLASSICAL APPROACH

MaslovIaropolschi

STAS 3300/2-85

Puzrevski Ghersevanov Frohlich

plastic zonesthe initial critical pressure coefficients Current technical regulations use for establishing the plastic pressure (ppl) or the initial critical pressure (pcr.in.) a relationship that is based on the theory of elasticity, for assessing 2D stress state within soil and the Mohr-Coulombs plasticity criterion for analyzing the emergence and development of plastic zones.

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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STANCIUS ALGORITHM

N1 N2 N3

N1N2N3

1B1N1+q1N2+c1N3=pcr.in.12B2N1+q2N2+c2N3=pcr.in.23B3N1+q3N2+c3N3=pcr.in.3

Different values for internal friction angle

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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5

MOHR-COULOMB MODEL

Foundation typeTestNo.cBq[kN/m3]kPa[m][kN/m2]F 1Test 118.7021.001.3037.40Test 218.7026.001.6146.30Test 318.7032.312.0057.54F 2Test 119.0022.003.5028.50Test 219.0017.002.7022.02Test 319.0018.863.0024.43F 3Test 118.5016.006.0041.63Test 218.5021.007.8854.64Test 318.5010.674.0027.75

Soils and foundations characteristics

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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MOHR-COULOMB MODEL

the coefficients values are not significantly different for internal friction angles below 20.

- larger differences, but not significant, occur for higher internal friction angles than 20

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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HARDENING SOIL MODEL

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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HARDENING SOIL MODEL

A very small difference (2-13%) between N2 coefficient values determined by the two methods (ET and HS)In the case of N1 coefficient the differences are between 162% and 262% and for N3 coefficient the differences are between 23% and 62%.N1N2N310262%2%23%20193%-3%39%30162%-13%62%

The percentage differences between the initial critical pressure coefficients values determined by two methods

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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CONCLUSIONSUsing Stancius algorithm and HS model implemented in the numerical analysis software PLAXIS 2D, new values were determined for the coefficients N1, N2 and N3, in the 2D strain state, values that lead to a better appreciation of the values of the initial critical pressure for soils subjected to continuous foundations respectively to lower costs for making these foundations.

The Gheorghe Asachi Technical University of IASIDoctoral StudiES for europeAn performanCES In research and inovation (Cuantumdoc) - ID 79407Strategic project funded for period 2010-2013European Social Found

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The basic parameters used by the HS constitutive model are the parameters corresponding to the Mohr-Coulombs failure criterion (c, , and ) and in addition interfere: the secant modulus from the standard drained triaxial test (), the tangent modulus from the oedometer test () and the unloading/reloading modulus ().