3) THE MECHANICAL ARRANGEMENT OF SOIL, FOUNDED ON THE COULOMB-HVORSLEV FAILURE CRITERION

At present, Coulomb-Hvorslev equation is understood with two meanings on the soil mechanics. The conventional angle of internal friction and cohesion of soil are shown as φ and c on the Fig. 1, but there is another way of thinking of this failure criterion on the original sense, which is adopted to the true angle of internal friction and true cohesion of soil, occuring on failure plane of the soil actually. On Fig. 1, the true angles of internal friction and true cohesions are shown as φ_1, φ_2 and c_1, c_2. c and φ are obtained from shearing test (triaxial compression test) to the condition of soil with equivalent water content, when soil is sheared. To these meanings of this failure criterion, the mechanical properties of soil of several kinds (clay → sand) were analyzed in this study. Conclusively, the property of shearing strength of soil is arranged to the three ranges of conventional angle φ as following, 1. φ>26°, φ=φ 2. 26°>φ>20°, φ>φ 3. 20°>φ, φ≫φ The relation between φ and φ is shown graphically on Fig. 10, and the values of φ and φ shown are those on the consolidated quick shear of soil.