Experimental System of Hydrodynamic Action of Dunhuang Mogao Grottoes under Temperature-Humidity-Mechanical (THM) Coupling

In order to thoroughly investigate the weathering mechanism of the murals in Dunhuang Mogao Grottoes, based on the independently developed hydrodynamic test system of the surrounding rocks under the combined action of temperature, humidity, and stress, this study performed the liquid water adsorption test and gaseous water adsorption test of the surrounding rocks of the support body of Dunhuang Mogao Grottoes, as well as the softening test of the strength of liquid water adsorbed by the rock samples. The experimental results are as follows: (a) – curve and ln –ln curve of the three types of black sandstone rock samples obtained by analyzing the nonpressure water absorption experiment data indicate that the – curve of the rock samples showed a similar trend with time, with the initial curve being steep and rapid increase in the water absorption; the double logarithmic curve of water absorption is convex and tends to be saturated. (b) The absorbing water softening test analysis was carried out for four types of siltstone specimens with intensity of pressure; bibulous rate was found to vary with time, and sample parameters such as compressive strength and elastic modulus decreased linearly with increasing water absorption at different times of uniaxial compression test. (c) Through the summer and winter and cave surrounding rock within the sample, the gas adsorption of water simulation was combined with the adsorption curve analysis, indicating that the adsorption characteristics of the surrounding rock and the correlation of larger sample depend on season. These research results provide a reliable theoretical basis and technical support for the protection of the murals in the Mogao Grottoes of Dunhuang and the prevention and control by salt damage.