The effect of strain rate on compressive strength of water saturated sandstone

The strength of rock materials is largely affected by water, and the static properties have been widely studied before, while there is virtually no data for dynamic compressive strength of saturated rock at different strain rates. In order to comprehensively investigate the effect of water on the dynamic compressive strength of rock, the Split Hopkinson Pressure Bar technique was applied to conduct dynamic compressive tests on both dry and saturated sandstone specimens at a wide range of strain rates. The test results showed that the compressive strength of both dry and saturated sandstone specimens was rate dependent, and the compressive strength of saturated specimens had stronger rate dependence than that of dry specimens. The Water Affecting Factor (WAF), as the ratio of the strength under dry state over that under saturated state, was introduced to describe the effect of water on the compressive strength at different strain rates, the WAF under static condition was close to 1.38, and the WAF decreased with the increase of strain rate. When the strain rate reached 190/s, the WAF reduced to 0.98, i.e., the compressive strength of saturated specimens was higher than that of dry ones at that time.