Estimation of uniaxial compressive strength from point load strength, Schmidt hardness and P-wave velocity

Uniaxial compressive strength is considered one of the most important parameters in the characterization of rock material in rock engineering practice. The study investigated correlations between uniaxial compressive strength and point load index, P-wave velocity and Schmidt hardness rebound number together with the effects of core diameter size. A total of 150 core samples at five different diameters (54, 48, 42, 30 and 21 mm) were obtained from sandstone, limestone and cement mortar. Ten saturated samples at each diameter (length:diameter ratio 2:1) were prepared from each of the three materials. The best correlations were found between uniaxial compressive strength and point load or Schmidt hammer values. The closest relationship was observed for the 48 mm diameter cores.RésuméLa résistance à la compression simple est considérée comme l’un des paramètres les plus importants pour caractériser la résistance de la matrice rocheuse dans les applications de la mécanique des roches. L’étude s’est intéressée aux corrélations entre la résistance à la compression simple et l’indice d’écrasement entre pointes, la vitesse des ondes P et l’indice de rebond au marteau de Schmidt, considérant de plus l’influence du diamètre des carottes testées. Au total, 150 échantillons de grès, calcaires et mortiers de ciment, dans cinq diamètres différents (54, 48, 42, 30 et 21 mm) ont été préparés. Dix échantillons saturés ont été testés pour les trois types de roche et pour chaque diamètre (ratio longueur/diamètre = 2/1). Les meilleures corrélations ont été trouvées entre la résistance à la compression simple et la résistance entre pointes ou l’indice de rebond de Schmidt. Les relations les plus précises ont été obtenues pour les échantillons de diamètre 48 mm.

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