Uniaxial compressive strength (UCS), Brazilian tensile strength (BTS) and point load strength (I s) of rocks are commonly used for the rock engineering applications. These important rock properties are strongly influenced by the water saturation. In this study, to investigate the effects of water saturation on the strengths of marbles, the UCS, BTS and I s tests were carried out on eight different marble types in the laboratory. The evaluation of results showed that the strength losses due to saturation ranges from 5.0 % to 25.3 % for UCS, from 5.1 % to 20.9 % for BTS, and from 5.6 % to 14.4 % for I s, respectively. The ratios between saturated and dry strength ranges from 74.7 % to 94.9 % for UCS, from 79.1 % to 94.9 % for BTS, and from 85.6 % to 94.4 % for I s, respectively. Linear regression equations between saturated and dry-rock strength values were also derived. The saturated UCS, BTS
Uniaxial compressive strength (UCS), Brazilian tensile strength (BTS) and point load strength (I s) are important properties of rocks. These strengths are generally used for the design of rock structures constructed in surface and underground. The water saturation strongly affects the strength of rocks. Although there is no generally accepted explanation for the effect of water content on the rock strength, several mechanisms are often used to explain it:
Fracture energy reduction,
Capillary tension decrease,
Pore pressure increase,
Frictional reduction, and
Chemical and corrosive deterioration [1]. Several researchers have investigated the effect of water saturation on the strengths of several rocks. Colback and Wiid [2] demonstrated a 50 % loss in UCS from the dry to the saturated conditions for shale and quartzitic sandstone. Burshtein [3] found that an increase in moisture content from 0 to 4 % decreased the UCS by 50 % for a quartz arenite. On the other hand, he showed that an increase in moisture content to 1.5 % reduced the UCS to approximately a third of its initial value for clayrich sandstone. Van Eeckhout [1] studied the effect of humidity on the strength and elastic properties of coal mine shales. He concluded that moisture lowers the work of fracture and increases the internal crack, hence lowering shale strength. Dyke and Dobereiner [4] investigated the variation in UCS with moisture content for three sandstones. They found that an increase in moisture content tends to reduce the range of elastic behaviour by promoting stress corrosionaided microcracking at low levels of applied stress. They also found that generally the weaker the rock, the more sensitive it is to changes in moisture content. Hawkins and McConnel [5] investigated the influence of the mineralogy and texture on moisture sensitivity. They found that the degree of sensitivity of sandstone to moisture content is controlled primarily by the proportions of quartz and clay minerals present and to a lesser extent by the rock microfabric.
