Abstract
The authors have tried to interplete the shear and compression strength of green sand from the standpoint of friction between sand grains. Systematic experiments have done to determine these two strengths as a function of porosity and moisture of the sand. And these results were analysed and discussed. The results are as follows : 1. The shear strength of green sand S varies linearly with the stress normal to the shear plane N, i. e., S = S0 + μN where S0 and μ are constant respectively when the conditions of sand are kept constant. This expression corresponds to the friction phenomena in ordinary cases when S0 = 0. S0 obtained in the experiments coinsides fairly with the tensile strength T of the same sand in the same conditions reported previously by the authors. μ, the coefficient of friction increases from 0.6 to 1.0 with decreasing porosity in every cases, and is independent of moisture and size of sand grains. 2. μ obtained in the experiments coinsides fairly well with the tangent of rest angle of dry sand in the same porosity. 3. The compression strength of green sand C is (5 − 20 times) as large as the tensile strength T of the same sand in the same conditions, and they are related as follows ; T/C = S0/C = (1/2)(1−μ)
