Effect of Water on Long-Term Strength of Column Rocks Based on Creep Behavior in Yungang Grottoes, China

Abstract

The long-term strength of rock load-bearing elements is an important mechanical index to determine its bearing capacity and preservation when protecting cultural relics made of stone. In this paper, uniaxial compressive creep experiments of medium-coarse sandstone from the columns of the Yungang Grottoes were performed on both dried and water-saturated samples. The effects of rock-water interaction on the long-term strength of rocks and on the bearing capacity to evaluate safety were determined. The experimental results show that the instantaneous strength and long-term strength of the medium-coarse sandstone in a water-saturated state were lower than the dried samples. The creep properties of the saturated rock were more obvious and the time needed to achieve a steady state creep was longer. The safety factors of the long-term bearing capacity of water-saturated rocks were not high enough, which indicates the possibility of unstable damage to the columns. It is recommended to strengthen the column in a timely manner to prevent damage and potential safety issues, particularly waterproofing the columns for addition protection. Finally, these experimental results provide a reference for the long-term strength evaluation of rock columns, and provide a theoretical basis for waterproofing the World Cultural Heritage, Yungang Grottoes.