###### Abstract  
The stress-strain characteristics of compressed sandstone are affected by many different factors. The study on the evolution law of the strain field of compressed sandstone is of great significance for disaster prediction and warning during the construction process of geotechnical engineering. In this paper, uniaxial compression tests of red sandstone of 100 mm height and 50 mm length and width were carried out under the conditions of (1) different loading rates, (2) different particle sizes and (3) different inclination angles of prefabricated fractures. Stress-strain curves corresponding to different conditions were presented, the evolution of strain field on the sample surfaces was analyzed with the help of Digital Image Correlation technology and the relationship between the stress-strain curves and the strain field was preliminarily given. This study may be helpful for obtaining a deeper understanding of the deformation and failure mechanism of sandstone under uniaxial compression. sandstone; uniaxial compression; Digital Image Correlation method (DIC); strain field evolution; damage +
Footnote †: journal: Applied Sciences  
sandstone samples at different rates. The results showed that with the increase in loading rate, the acoustic characteristics, such as hit, counting and events of acoustic emission, decreased significantly, and the acoustic emission energy increased significantly. The different rock mechanical properties of sandstone are mainly due to the differences in rock formation mechanisms and the influence of the external environment, while the essential reasons for the differences in the internal structure of sandstone depend on the meso-structure and mineral composition of the sandstone [8]. Sandstone is an anisotropic complex formed by the cementation of mineral particles of different particle sizes, and the properties of the internal mineral particles will have an impact on the mechanical properties of rock. [PERSON] et al. [9] used 0.725-2.03 mm silica sand to study the effect of particle size on the wear rate in the process of rock crushing. The results showed that the wear rate increases with the increase in particle size. [PERSON] et al. [10] carried out many impact tests on calcareous sand under different impact test times, and analyzed it by using Digital Image Correlation technology. The results show that with the increase in the number of impact tests, the crushing degree of calcareous sand with a size of 2-5 mm is the highest. [PERSON] et al. [11] carried out compression tests on macadam with different particle size distributions, and studied the influence of different particle size distributions on the fractal characteristics of waste rock filling materials under compression. The results showed that the specimen with more coarse particles has higher stress in the stable deformation stage and higher strain at the same stress level. At the same time, there are many micro-cracks in natural sandstone. Under the action of external load, the cracks in the rock undergo a series of development, such as closure, expansion and penetration, resulting in rock deformation and instability. The distribution and stress state of cracks in the rock will have a great influence on the mechanical behavior of rocks [12]. As early as the 1960s, domestic and foreign scholars began to study the failure mechanism of fractured rock mass under compression or tension conditions. [PERSON] [13] and [PERSON] [14] et al. carried out uniaxial and biaxial compression tests on brittle rocks with single fractures, respectively, and analyzed the mechanism of crack propagation in brittle rocks. [PERSON] [15; 16] selected gypsum materials to make rock-like specimens, and conducted uniaxial compression tests on rocks containing single fractures. It was found that under compression conditions, cracks in the gypsum were mainly wing cracks and secondary cracks.