Bao Xiankai, Qiao Jianlong, Yu Chaoyun, Tian Baolong, Wang Lingyu, Zhang Xiaofan
School of Civil Engineering, Inner Mongolia University of Science and Technology, Inner Mongolia, Baotou, 014010, China.
Inner Mongolia Autonomous Region Building Structure Disaster Prevention and Mitigation Engineering Technology Research Center, Inner Mongolia University of Science and Technology, Inner Mongolia, Baotou, 014010, China.
Sci Rep. 2024 Jul 23;14(1):17012. doi: 10.1038/s41598-024-67833-w.
In order to study the damage properties of red sandstone under combined action of temperature, water and stress, the uniaxial compression test was carried out for red sandstone after immersing in water for 0.5 h, 1 h and 3 h at 25 ℃, 55 ℃, 85 ℃ and 95 ℃, the mechanical properties, characteristic stress points, acoustic emission RA-AF parameters and failure forms of red sandstone were analyzed, the damage constitutive equation was established, and the damage properties of red sandstone were studied. The results showed: (1) temperature could significantly improve the saturated water content percentage of red sandstone. With the increase of temperature, the saturated water content percentage showed a trend of increase first and then decrease, and was the largest at 55 ℃; with the increase of temperature, the mechanical parameters (peak intensity, elasticity modulus, and stress at start point of expansion) decreased first and then increased, and was the smallest at 55 ℃; (2) the ratio of crack initiation stress to peak stress (σci/σf) initially increases and then decreases with rising temperatures for the same soaking duration. Conversely, it initially decreases and then increases with extended soaking time at the same temperature. The RA-AF acoustic emission signals predominantly occur in the tensile region at each stage account for a relatively large proportion, with the proportion of signals in the shear region significantly increasing as soaking time extends, corresponding well with the observed damage patterns. (3) By considering the damage due to temperature and water as Initial damage to red sandstone and the damage due to stress as load-induced damage, a damage variable based on the Weibull distribution function was established. The comprehensive damage constitutive equation derived from this can be applied to water-saturated red sandstone below 100 ℃. The findings provide theoretical reference for practical engineering applications.
为研究红砂岩在温度、水和应力耦合作用下的损伤特性，对红砂岩在25℃、55℃、85℃和95℃分别浸泡0.5h、1h和3h后进行单轴压缩试验，分析红砂岩的力学性能、特征应力点、声发射RA - AF参数及破坏形式，建立损伤本构方程，研究红砂岩的损伤特性。结果表明：(1)温度可显著提高红砂岩的饱和含水率。随着温度升高，饱和含水率呈先增大后减小的趋势，在55℃时最大；随着温度升高，力学参数（峰值强度、弹性模量、扩容起始点应力）先减小后增大，在55℃时最小；(2)相同浸泡时间下，裂纹起裂应力与峰值应力之比(σci/σf)随温度升高先增大后减小。反之，在相同温度下，随着浸泡时间延长，该比值先减小后增大。各阶段RA - AF声发射信号主要集中在拉伸区域，占比较大，随着浸泡时间延长，剪切区域信号占比显著增大，与损伤模式吻合较好；(3)将温度和水引起的损伤视为红砂岩的初始损伤，应力引起的损伤视为荷载损伤，建立基于 Weibull 分布函数的损伤变量。由此推导的综合损伤本构方程可应用于100℃以下的饱水红砂岩。研究结果为实际工程应用提供了理论参考。
