A teacher and three students planted four trees for a group. Four people plant four trees. * * * Planting 100 trees. Then there is such a group 100/4 = 25, so there are 25 teachers. There are students 25 * 3 = 75.

GTM experimental machine simulates the interaction between tire and pavement as much as possible. Through rotary compaction, the density of asphalt mixture in the simulation reaches the density produced when automobile tires actually act on the road surface, that is, vertical pressure is applied to the specimen (the pressure reduction is determined by testing the actual pressure of automobile tires on the road surface), and the specimen is rotary compacted to an equilibrium state under this pressure.

Specific explanation:

GTM section is an asphalt test section.

GTM design method: American engineers' rotary compaction shears (GTM), as a tool for engineers' theoretical research and practical application, were specially developed and invented by American engineers to solve the problem that bomber runways are easily damaged.

GTM is a mechanical simulation of flexible pavement under load. This testing machine uses a kneading method similar to that of a road roller in construction to compact asphalt mixture, simulating the action of field compaction equipment and subsequent traffic, so it has the flexibility to change the vertical pressure.