Experimental Study on Internal Pressure Induced by Granular Cargo

The improvement of the estimating accuracy of bulk pressure acting on a cargo hold is indispensable for evaluating the strength of a bulk carrier exactly. Though various researches about earth pressure or granular cargo pressure have been performed, no established method for ship structures is yet found. In such an environment, authors carried out the measuring tests of granular cargo pressure with scaled hold models and showed the estimation method based on Janssen's theory in the previous papery1).In this paper, authors derived the equation to be applicable for the estimation of static pressure acting on an inclined wall on the basis of Janssen's theory and confirmed its validity through the comparison of calculated value and experimental results.Furthermore, authors proposed the simple and practical equation to estimate static and dynamic pressure due to bulk cargo. On static pressure, the fact was taken into consideration that the static pressure acting on inner bottom plates was not equal to the value of γ×h. That is, the new estimation method was proposed by modifying the cargo profile. And the coefficients of earth pressure were improved based on the experimental results. As for dynamic pressure, vertical acceleration and rolling were considered as predominant motions for ship structures. Simple methods were proposed by introduction of apparent acceleration for dynamic pressure due to vertical acceleration and application of SR2072) method for dynamic pressure induced by roll motion.