Swelling Characteristics of Red Sandstone Under Cyclic Wetting and Drying

Abstract

The effect of repeated swelling of rock on tunnels and other structures becomes more apparent with the continuous development of the transportation infrastructure in China. Tests on the free swelling ratio, lateral constraint swelling ratio, and lateral constraint swelling stress were conducted for different dry–wet cycles and drying temperatures, with the samples taken from Zhuzhou in Hunan Province (China). The test results show that the free swelling ratio, lateral constraint swelling ratio, and swelling stress of rock are all dependent on time. The swelling phases can be characterized as rapid, moderate, and slow phases. The dry–wet cycle and drying temperature have a significant effect on the swelling behavior of red sandstone. At larger axial and radial free swelling ratios, the lateral constraint swelling ratio and swelling stress occur at a higher drying temperature. Furthermore, the lateral constraint swelling ratio and swelling stress first increase with an increasing number of cycles and then gradually decrease and reach maximum values in the second and third cycles, respectively. Based on the sigmoid and power functions, the time-history models for the lateral constraint swelling ratio and lateral constraint swelling stress are established, considering the effects of the cycle number and drying temperature. In addition, the results of this study are significant and may serve as an engineering guide for the swelling of rock during construction.