Determination of load action ranges in static and dynamic tests of subgrades by applying rigid plates

Soil bearing capacity and compactness testing by rigid plates is commonly used during ground investigations and work quality control on most sites where enclosed and right-of-way structures are being built. Typically, the VSS (static plate bearing) test apparatus is used for this purpose. In recent years LFG falling weight deflectometers (dynamic plate load tests) have been increasingly used on building sites. This paper presents the theoretical bases relating to load testing by rigid plates. Several numerical calculations were made for selected soils, presenting the load distribution, corresponding to the range of the above tests in the subgrade. The type and state of soil as well as the applied load values have been confirmed to have a decisive bearing influence on the load action range. The assumption of the constant measuring range for static plate bearing tests (amounting to about 2-3 plate diameters) and for dynamic plate load tests has not been proved by the numerical calculations based on the theory of rigid foundations.