## 3 Experimental Results and Analysis  
### Uniaxial Compression Test  
At three different loading rates, the uniaxial compressive stress-strain curves and post-damage morphology of sandstone are shown in Figures 4 and 5. The physical and mechanical parameters are shown in Table 1. It can be seen that, although the stress-strain curves obtained at different loading rates have slightly different patterns, the sandstone undergoes four processes, from intact to damaged: first it is compacted, then it undergoes elastic and plastic deformation. The rock was finally destroyed. When the test was conducted with a loading rate of 0.2 KN/S, the average value of peak stress of sandstone was 41.17 MPa; the average value of peak strain was 0.0129, and the average value of elastic modulus was 35.42 GPa. The damage form was shear damage, with two oblique shear surfaces through the specimen, a small number of large-scale rock pieces along the shear surface, accompanied by a continuous \"friction\" sound. When the loading rate was increased from 0.2 to 0.5 KN/S, the average value of peak stress in sandstone was 42.27 MPa, with an increase of 0.25%; the average value of peak strain was 0.00787, with a decrease of 38.99%, and the average value of elastic modulus was 37.44 GPa. The damage form was mainly in tension shear, accompanied by splitting damage, multiple penetrating fracture surfaces, and along the fracture surface. The damage form is mainly in tension shear, accompanied by splitting damage, with multiple penetration fracture surfaces; along the fracture surface appears a large number of medium-scale rock blocks, which are accompanied by continuous bursting sound. The damage form is mainly in tension shear, accompanied by splitting damage, multiple penetrating rupture surfaces, and multiple medium-scale rock blocks along the rupture surface, which are accompanied by a continuous bursting sound. When the loading rate was increased from 0.5 to 1 KN/S, the average value of peak stress of sandstone was 44.45 MPa, with an increase of 5.16. The average value of peak strain was 0.00556, with a decrease of 29.35%, the average value of elastic modulus was 46.19 GPa, and the damage form was mainly in the form of splitting blocks, with multiple penetrating splitting surfaces; a large number of small rock blocks formed along the splitting surface. The damage is mainly in the form of splitting blocks, with multiple penetrating cleavage surfaces, and a large number of small rock pieces formed along the cleavage surface, with a continuous bursting sound, loud noise, and small amount of rock chips flying out during the damage.  
Figure 4: Stress-strain curve under uniaxial compression.  
From the results, it can be seen that there is a great difference in the response of the same rock at different loading rates. As the loading rate increases the strength of sandstone increases, the elastic modulus becomes larger, and the peak strain is reduced. As the loading rate increases, the number of fragments increases, scale becomes smaller, and sound is more violent after the sandstone is broken. The damage form is \"shear damage tensile shear damage \(\rightarrow\) splitting damage\".