VTI performs static plate loading as in the Swedish Transport Administration method description "VVMB 606," based on the German standard "DIN 18134".
Static plate loading is a method used to measure the bearing capacity of unbound layers. These may be the normal layers of a road, the subgrade, the sub base layer or the base layer. It may also be the foundation layer for building construction, such as the layer under a concrete slab.
During plate loading a circular steel plate is loaded using a jack mounted against a counterweight, often a heavy work vehicle. Loading is carried out in two stages: the first has a normal maximum load of 0.5 MPa (about 3.6 tonnes) and the second loading is about 90 per cent of the first. The stages consist of several steps. The deformation of the plate is recorded at each step.
The deformation modules Ev1 and Ev2 are calculated from the loading and deformation values.
Demands are often placed on Ev2 and the ratio of Ev2/Ev1. Requirements can be found in "AMA Anläggning 10" which for road contexts refers to the Swedish Transport Administration's "TRVKB 10 Obundna lager". These documents also regulate how many points thats ought to be measured. What requirements apply for each object is governed by the contract between client and contractor.
VTI generally performs this work in Östergötland and adjacent counties, but can also undertake assignments in other parts of the country.
- one point takes about 30 minutes to measure
- the client provides the counterweight (about 8 tonnes)
- the measurement is reported in a document containing a summary and depression data for each point
- personnel (900 SEK/hour)
- equipment (1500 SEK/day)
- vehicle and travelling expenses are added.