Cooling Methods under High-Temperature Effects on Creep Properties and Nonlinear Creep Damage Model of Quartz Sandstone

Abstract

In order to compare and study the creep mechanical behavior of quartz sandstone under the action of different cooling methods in high temperature, firstly, triaxial creep tests of quartz sandstone after natural cooling and water cooling are carried out, and creep curves under two conditions and different temperatures are obtained, respectively. Meanwhile, the mesodamage characteristics of quartz sandstone under the action of different cooling methods are analyzed. Based on experimental data and statistical damage theory, an improved Burgers creep damage model is proposed, and the model parameters are subjected to sensitivity analysis. The test results show that the creep process of quartz sandstone under different cooling methods has three-stage characteristics, and the creep rate increases gradually with temperature, whereas the long-term strength decreases gradually. Under the same temperature, the creep rate of quartz sandstone under water cooling is higher than that under natural cooling, whereas the long-term strength is lower than that of natural cooling. The mesoscopic test also shows that the damage degree of water cooling to the rock is higher than that of natural cooling. Finally, by comparing with the experimental data, it is found that the proposed improved Burgers creep damage model can effectively reflect the influence of different cooling methods on the creep properties of quartz sandstone. The results of this paper can provide important scientific significance for the damage assessment, repair, and reinforcement of tunnel surrounding rock and other structures under high temperatures.