## 3 Results and Discussion  
### Bearing and Deformation Characteristics of Gangue Slurry  
#### 3.1.1 Change of Compression Rate  
(1) Instantaneous loading  
Based on the data obtained from the experiment, the compression rate stress curve of the gangue slurry under instantaneous loading conditions was calculated using Equation (2), as shown in Figure 7.  
As shown in Figure 7, it can be seen that:  
1. During the instantaneous loading process, the axial compression rate of gangue slurry with different fluidities is approximately an exponential function of stress, and there is a deformation threshold. In addition, the deformation threshold is negatively correlated with the fluidity. 2. The deformation threshold of I4 and I5 is lower than 20 MPa, and the entire process of compression rate change can be divided into three stages:  
Figure 7: Compression rate–stress curve of gangue slurry under the instantaneous compression test. * Rapid deformation stage (0-4 MPa). The compression rate increases rapidly with the increase of stress, and the deformation generated in this stage accounts for about 45% of the total deformation. In the initial loading stage, the slurry has large pores and poor stability, and the contact area and compression degree of gangue particles are small, exhibiting characteristics of rapid deformation and poor bearing performance. At this stage, the compression rate-stress curves of I4 and I5 almost overlap, and the degree of bearing deformation of the slurry is less affected by the fluidity. * Slow deformation stage (4-14 MPa). The compression rate decreases with the increase of stress, and it gradually decreases with the increase in deformation degree. The compression deformation of gangue slurry mainly occurs in this stage, accounting for about 50%. At this stage, the compression rate of I4 increases slower than that of I5, and the influence of fluidity on the deformation of the slurry increases. There are significant differences in the load-bearing deformation capacity of different slurries. The pores in the slurry decrease with the increase in compression rate, and the gangue particles undergo crushing and backfilling under pressure, resulting in close contact. The positions between particles are relatively balanced, and the resistance to deformation is enhanced. * Stable deformation stage (14-20 MPa). After entering this stage, the compression rate-stress curve is almost parallel, the compression rate tends to a constant value, and the deformation that occurs when the stress increases is almost zero. The difference in compression rates between I4 and I5 during this stage decreases compared to that in the slow deformation stage. After the compression rate reaches the threshold, the broken small particles have filled the pores, forming a stable pore structure. At this time, the elastic-plastic structure of the slurry changes under stress, affecting its later mechanical strength. * The deformation threshold of I1-I3 is higher than 20 MPa. Throughout the entire transformation process, the slurry only goes through the rapid deformation stage and the slow deformation stage. When the stress is loaded to 20 MPa, the stable stage is not reached, while the compression rate shows a stable trend. Compared to the deformation process of I4 and I5 slurries, the rapid deformation stage of I1-I3 slurries is shorter and their proportion of deformation is smaller, while the slow deformation stage of I1-I3 slurries lasts longer and their proportion of deformation is larger. * The compression rate of slurries with different fluidities increases with the increase of fluidity. When the axial stress reaches 20 MPa, the extreme values of compression rate are 32%, 42%, 45%, 53%, and 55%, respectively.