The Author measured the stress generated by a pneumatic tyred roller (25t) and compared the theoretical values which are calculated under an assumption of the validity of the principle of superposition (Fig. 4-5). Pneumatic pressure of the tyred roller (3. 8 kg/cm²) used for contact pressure. Theoretical stress distributions of Z, Y and X directions are shown Fig. 1-5. Fig. 9-1-9-4 show the experimental stress distributions X direction for Cr. Rm and Tr.
From those studies we find as follows,
(1) Theoretical values almost coincide with the measured values in the case of low speed of the roller or compaction on cohesive soil (Cr., Rm.).
(2) Stress grows larger with the compactive speed of the roller and with the roughness of the ground.
(3) Theoretically and experimentally, the vertical stressσ_z is much larger than horizontal stress σ_x, σ_y which is generated by the vertical load and horizontal load due to the friction between the roller and the soil surface. So that it can be said that σ_z mainly contributed to the compaction.