Glossary of terms
Plate load test
The deformation modulus Ev
The deformation modulus Ev is a parameter for the deformability of the soil. Decisive – for the assessment of compression – is both the ratio of the values Ev2: Ev1, and the value Ev2. According to DIN 18134 Ev is determined by a polynomial of 2nd degree and the method of least squares. The physical unit is NM/m².
Ev = 0,75 * (plate diameter D [mm]) * (Difference of the normal stress between the loads of 0,3*σmax and 0,7*σmax [MN/m²]) / (Difference of the settlement of the load plate at these load steps [mm]).
The deformation modulus ME
The deformation modulus ME is a parameter for the deformability of the soil. (Switzerland, Slovenia)
ME = (plate diameter D [mm]) * (Difference of the normal stress between two loads [MN/m²}) / (Difference of the settlement of the load plate at these load steps [mm])
The deformation modulus MD
The deformation modulus ME is a parameter for the deformability of the soil. (Italy)
MD = (plate diameter D [mm]) * (Difference of the normal stress between two loads [MN/m²}) / (Difference of the settlement of the load plate at these load steps [mm])
The deformation modulus Ev1, Ev2, Ev3
Ev1 is the modulus of the first load cycle of the plate load test. Physical unit is MN/m².
Ev2 is the modulus of the second load cycle of the plate load test. Physical unit is MN/m².
Ev3 is the modulus of the third load cycle of the plate load test. Physical unit is MN/m². (rare)
Subgrade reaction ks
The Westergaard’s modulus of subgrade reaction ks is a parameter of the resilience of the soil surface under a distributed load. The average normal stress at a settlement of the load plate of 1.25 mm is measured. (according to DIN18134). The diameter of the load plate is typically 762mm.