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.