Relationship Between Dynamic Tensile Strength and Pore Structure of Saturated Concrete under Lateral Pressure

The dynamic properties of concrete in two states (saturated and dry) were compared and analyzed through a series of dynamic biaxial tensile-compressive (T-C) experimentals. All specimens were subjected to constant biaxial T-C stress ratios (0.5:−1, 0.25:−1, 0.1:−1, 0.05:−1 and 1:0 respectively) at different strain rates (10−5s⁻¹ to 10−2s⁻¹). It was found that the biaxial T-C ultimate strengths of both kinds concrete closely relate to the lateral pressure of the specimen, and the independent tensile and compressive strength increases with the increase of strain rate. In the case of exerting lateral pressure, the failure states of specimens show same manner as that of the uniaxial tensile specimens, which indicates that the specimens were completely fractured under tensile loading. The test results show that the biaxial T-C strength of saturated concrete is lower at strain rates of 10−5s⁻¹, whereas it is higher at the other three strain rates (10−4s⁻¹, 10−3s⁻¹ and 10−2 s⁻¹). This distinct difference indicates that saturated concrete is more rate sensitive under lateral pressure. Through mechanical analysis the article explains the reason of this phenomenon is mainly dued to the beneficial tensile stress of the pore water surface and the Stefan effect. Meanwhile, the strength prediction expression of saturated concrete was established under the condition of stress ratio and strain rate are considered simultaneously.