Soil compaction measurement on moving platform

An apparatus for the in-situ measurement of the stiffness of a surface, the apparatus comprising:

• a platform, which is movable relative to the surface;
• a rigid shoe supported by the platform and having an external rolling belt that travels along a closed-loop path and has an elongated segment for engaging the surface;
• and
• a stiffness measurement device, which generates a dynamic force and is mounted to the rigid shoe such that the dynamic force is applied to the surface through the rigid shoe and the rolling belt, and the device receives a dynamic response from the surface through the rigid shoe and the rolling belt.

A method of making an in-situ measurement of the stiffness of a surface, the method comprising:

• (a) moving a platform relative to the surface;
• (b) carrying a stiffness measurement device on the platform;
• (c) supporting the stiffness measurement device in a stationary position relative to the surface for a measurement period during movement of the platform along the surface;
• (d) applying a vibratory force from the stiffness measurement device to the surface;
• and
• (e) sensing motion of the surface in response to the vibratory force and generating a respective measurement signal, which is representative of the surface stiffness.

An apparatus for the in-situ measurement of the stiffness of a surface, the apparatus comprising:

• a platform, which is movable relative to the surface;
• a roller supported by the platform for engaging the surface;
• and
• a stiffness measurement device, which generates a dynamic force and is mounted to the roller such that the dynamic force is applied to the surface through the roller, and the device receives a dynamic response from the surface through the roller, wherein the device comprises a set of one or more sensors, the set having an output representative of the dynamic force applied to the roller and an output representative of the dynamic response of the surface.