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Modulus of Subsoil Reaction According to NF P 94-282

The modulus of subsoil reaction kh according to NF P94-282:2009-03 depends on bending stiffness of sheeting structure Estr Istr and pressuremeter (Menard) modulus EM. The modulus of subsoil reaction is given by the following formula:

where:

kh

-

modulus of subsoil reaction [MN/m3]

EM

-

pressuremeter modulus according to Menard [MPa]

α

-

empirical coefficient depending on the type of the soil, or type of the rock [-]

Estr Istr

-

bending stiffness of sheeting structure [MNm2]

B0

-

characteristic (unit) length of sheeting structure [1 rm]

E

-

modulus of elasticity of the material of the sheeting structure [MPa]

I

-

moment of inertia [m4/m]

Approximate values of empirical coefficient α [-] for various types of soils

Type of soil

Peat

Clay

Silt

Sand

Gravel

α

EM/pLM

α

EM/pLM

α

EM/pLM

α

EM/pLM

α

Overconsolidated

-

> 16

1

> 14

2/3

> 12

1/2

> 10

1/3

Normally consolidated

1

9 - 16

2/3

8 -14

1/2

7 -12

1/3

6 -10

1/4

Non-consolidated

-

7 - 9

1/2

5 - 8

1-2

5 -7

1-3

-

-

Approximate values of empirical coefficient α [-] for various types of rocks (according to degree of violation)

Type of rock

α [-]

Intact, strong

2/3

Slightly impaired, unweathered

1/2

Very poor, weathered

1/3

Metamorphic

2/3

Literature:

NF P94-282: March 2009, pp. 142 – 146.

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