Annex C.1
(informative)
Pressuremeter Test (PMT)
(1) The following is an example of the calculation of the bearing resistance of spread foundations using a semiempirical method and the results of an MPM test.
(2) The bearing resistance is calculated from
where:
R is the resistance of the foundation against normal loads;
A' is the effective base area as defined in ENV 19971;
σ_{v0} is the total (initial) vertical stress at the level of the foundation base;
p_{LM} representative value of the Ménard limit pressures at the base of the spread foundation;
p_{0} is [K_{0}(σ_{v} − u) + u] with K_{0} conventionally equal to 0,5, and F_{v} is the total vertical stress at the test level and u is the pore pressure at the test level;
k is a bearing resistance factor given in table C.1;
B is the width of the foundation;
L is the length of the foundation;
D_{e} is the equivalent depth of foundation.
Soil Category  p_{LM} [MPa] 
k  
clay and silt  A B C 
<0,7 1,2—2,0 >2,5 
0,8×[1 + 0,25 (0,6 + 0,4 B/L)×D_{e}/B] 0,8×[1 + 0,35 (0,6 + 0,4B/L)×D_{e}/B] 0,8×[1 + 0,50 (0,6 + 0,4B/L)×D_{e}/B] 
sand and gravel  A B C 
<0,5 1,0—2,0 >2,5 
[1 + 0,35 (0,6 + 0,4B/L)×D_{e}/B] [1 + 0,50 (0,6 + 0,4B/L)×D_{e}/B] [1 + 0,80 (0,6 + 0,4B/L)×D_{e}/B] 
chalk  1,3×[1 + 0,27 (0,6 + 0,4B/L)×D_{e}/B]  
marl and weathered rock  [1 + 0,27 (0,6 + 0,4B/L)×D_{e}/B] 
For additional information and examples, see Annex M
ANNEX C.2
(informative)
Pressuremeter Test (PMT)
(1) The following is an example of the calculation of the settlement, s, of spread foundations using a semiempirical method developed for MPM tests.
where:
B_{0} is a reference width of 0,6 m;
B is the width of the foundation;
λ_{d} and λ_{c} are shape factors given in table C.2;
α is a rheological factor given in table C.3;
E_{c} is the weighted value of E_{M} immediately below the foundation;
E_{d} is the harmonic mean of E_{M} in all layers up to 8×B below the foundation;
σ_{v0} is the total (initial) vertical stress at the level of the foundation base;
q is the design normal pressure applied on the foundation.
L/B  circle  square  2  3  5  20 
λ_{d} λ_{c} 
1 1 
1,12 1,1 
1,53 1,2 
1,78 1,3 
2,14 1,4 
2,65 1,5 
Type of ground  Description  E_{M}/p_{LM}  α 
peat  1  
clay  overconsolidated normally consolidated remoulded 
< 16 9—16 7—9 
1 0,67 0,5 
silt  overconsolidated normally consolidated 
> 14 5—14 
0,67 0,5 
sand  > 12 5—12 
0,5 0,33 

sand and gravel  > 10 6—10 
0,33 0,25 

rock  extensively fractured unaltered weathered 
0,33 0,5 0,67 
For additional information and examples, see Annex M.
ANNEX C.3
(informative)
Pressuremeter Test (PMT)
(1) The following is an example of the calculation of the ultimate bearing resistance, Q, of piles from the MPM test, using
Q = A k [p_{LM} – p_{0}] + P Σ [q_{si} · z_{i}]
where:
A is the base area of the pile which is equal to the actual area for close ended piles and part of that area for open ended piles;
p_{LM} is the representative value of the limit pressure at the base of the pile corrected for any weak layers below;
p_{0} is [K_{0}(σ_{v} – u) + u] with K_{0} conventionally equal to 0,5, and σ_{v} is the total vertical overburden pressure at the test level and u is the pore pressure at the test level;
k is a bearing resistance factor given in table C.4;
P is the pile perimeter;
q_{si} is the unit shaft resistance for soil layer i given by figure C.1 read in conjunction with table C.5;
z_{i} is the thickness of soil layer i.
Soil category  p_{LM} [MPa] 
Bored piles and small displacement piles  Full displacement piles  
clay and silt  A B C 
< 0,7 1,2—2,0 > 2,5 
1,1 1,2 1,3 
1,4 1,5 1,6 
sand and gravel  A B C 
< 0,5 1,0—2,0 > 2,5 
1,0 1,1 1,2 
4,2 3,7 3,2 
chalk  A B C 
< 0,7 1,0—2,5 > 3,0 
1,1 1,4 1,8 
1,6 2,2 2,6 
marl  A B 
1,5—4,0 > 4,5 
1,8 1,8 
2,6 2,6 
weathered rock  A B 
2,5—4,0 > 4,5 
(i)  (i) 
(i) Choose k for the closest soil category. 
soil category  clay and silt  sand and gravel  chalk  marl  rock  
pile type  A  B  C  A  B  C  A  B  C  A  B  
bored piles and caissons  no support mud support temp casing perm casing 
1 1 1 1 
1/2 1/2 1/2 1 
2/3 1/2 1/2 1 
– 1 1 1 
– 1/2 1/2 1 
– 2/3 2/3 2 
1 1 1 
4/5 4/5 3/4 
4/5 4/5 3/4 
3 3 3 2 
4/5 4/5 4 3 
6 6 – – 
hand dug caisson  1  2  3  –  –  –  1  2  3  4  5  6  
displacement piles  closed end prefab concrete cast in situ coated shaft 
1 1 1 1 
2 2 2 2 
2 2 2 2 
2 3 2 3 
2 3 2 3 
3 3 3 4 
1  2  3  3 3 3 3 
4 4 4 4 
4 4 – – 
grouted piles  low pressure high pressure 
1 1 
2 4 
2 5 
3 5 
3 5 
3 6 
2 – 
3 5 
4 6 
5 6 
5 6 
– 7 
For additional information and examples see Annex M.