Snowfall-related deterioration behavior of the Ming Great Wall in the eastern Qinghai-Tibet Plateau

Abstract

The Ming Great Wall in the Qinghai Province is an important section of the Great Wall of China. Most of this section is fabricated with rammed earth. The preserving environment of the Ming Great Wall is characterized by frequent snowfalls in winter, strong evaporation, and large diurnal temperature variations. Nearly all types of deterioration, including crazing, gully erosion, surface crust erosion, bottom sapping, and collapses, are evident in the Ming Great Wall in the Qinghai Province. Based on field investigations, the snowfall in winter and the presence of soluble salts are the primary factors causing the deterioration of the rammed earth. To investigate the coupled effect of freeze–thaw cycles and salinization on this deterioration process, a series of geotechnical tests are performed at Lanzhou University using samples collected from the collapse accumulation near the earthen sites. The test results showed that the microstructure damage in the rammed-earth materials caused by the freeze–thaw cycles and salinization is the primary controlling factor for the deterioration process of rammed-earth structures.