Wet rocks, whose engineering behavior is different from that of dry rocks, are commonly encountered in geotechnical engineering projects. Due to the considerable variations of texture and lithology, the extent of water-weakening effect is highly varied among different rock types, spanning from nearly negligible in quartzite to 90 percent of uniaxial compressive strength reduction in shale. Readers however often face difficulties in comparing the data published in different sources due to the discrepancy of manipulating and presenting experimental results. In view of this, the present review develops two flowcharts to facilitate a systematic review and compilation of the literature data. The results, which are presented in bar charts, reveal the variation of water weakening effects on different rock types, particularly focusing on uniaxial compressive strength (UCS) and modulus (E) obtained from quasi-static loading tests.


Strength and stiffness characteristics of rock are of a great fundamental importance for rock classification and design of structures in geotechnical engineering. In addition to intrinsic rock composition and structure, factors influencing the rock strength and stiffness including the test condition, temperature and water content were comprehensively reviewed by Hawkes & Mellor (1970), Dyke & Dobereiner (1991), Vasarhelyi & Van (2006). For rock engineering applications in particular, the water weakening effect on different rock types has been observed by many researchers (Burshtein 1969; Colback et al. 1965; Krokosky & Hisak 1968; Naghadehi et al. 2010; Obert 1946; Ruiz 1966; Simpson et al. 1968). A comprehensive literature review has been conducted to compile the results of water saturation effects on different rock types with respect to uniaxial compressive strength (UCS) and modulus (E). The results are reported and discussed in this paper.

2.1 Background

The present review compiles and reanalyzes the numeric data on water weakening effects on rock properties published from 1940 to 2014 in detail. The data records are first grouped according to rock types, of which the percentage reduction in the mechanical properties such as UCS and E due to water saturation are computed and compiled.

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