FRENCH CODE 1 NF P 11 212 DTU

FRENCH CODE 1) NF P 11 -212 - DTU 13. 2 (1978 & additional modifications 1991) II ) Fascicule 62 titre V III) Euro Code 7 : Geotechnical Design

DTU 13. 2 Micropiles : - Drilled - Diameter < 250 mm Classification based on the method of grouting

Design : - Structural bearing capacity - Geotechnical bearing capacity - Control tests

Structural bearing capacity : Micropiles (II, IV) - Steel is only considered in the design - Admissible stress - Service loads (ELS) : sa = 0. 5 se - Ultimate loads (ELU) : sa = 0. 75 se - Reduction of the section for corrosion - Buckling verfication (Mandel Method)

Geotechnical bearing capacity Friction forces only Qs = 2 p. Ds L qs Design Diameter (Ds) : Ds = a Dd (Dd = Drilled diameter) Values of a

Determination of friction qs -Cohesive soils (laboratory tests) -Without results from in-situ tests - Cone penetration tests - Pressuremeter test of Menard

Cohesive soils qs = b Cu b = 1 (low injection pressure) (Type I, II) b = 1. 5 (high injection pressure) (III et IV) -Without results from in-situ tests

Cone penetration test qs = qc /a

Pressuremeter test of Menard Classification (soil, type of micropile)

Reduction factor for qs Service loads (ELS) : 0. 5 Ultimate loads (ELU) : 0. 75

Control tests - Compression : 1 test / 200 micropiles - Tension : 1 / 50 - N < 25, without test, reduction of the bearing capacity by 1. 5