## 3 Results and Discussion
### Results of Shear Resistance Tests  
To assess the shear performance of the consolidated soil treated with the composite dust suppressant, a series of direct shear tests were conducted on soil specimens that had undergone natural curing for 28 days. The tests were performed using a standard direct shear apparatus, and the results were analyzed to determine the shear strength parameters of the soil, including the cohesion (c) and the angle of internal friction (\(\varphi\)).  
Figure 3: Stress–strain diagram for B1, B2, and B3.  
The shear stress at failure was measured three times for each soil sample, and the average value was taken. The measurement error remained within 5%. The shear stress-displacement curves obtained from the direct shear tests are presented in Figure 4a. These curves illustrate the relationship between the applied shear stress and the corresponding shear displacement for the consolidated soil specimens.  
Based on the analysis of the shear stress-displacement curves and the subsequent calculation of shear strength parameters, the following observations were made regarding the shear performance of the consolidated soil:  
The consolidated soil exhibited significantly higher shear strength compared to untreated soil. This enhancement in shear strength can be attributed to the binding effect of the composite dust suppressant, which strengthens the soil particles' interconnections and improves their resistance to shear forces.  
The cohesion (c) and the angle of internal friction (\(\varphi\)) of the consolidated soil were found to be notably higher than those of untreated soil. The increased cohesion indicates a stronger bonding between soil particles, while the higher angle of internal friction reflects an improved ability of the soil to resist shear deformation through frictional forces between the particles [30].  
A shear strength envelope was constructed based on the results of the direct shear tests, as shown in Figure 4b. The determination coefficient for the solidified soil is 0.86, while it is 0.91 for the control group. This envelope represents the maximum shear stress that the consolidated soil can withstand at different normal stress levels. The slope of the envelope corresponds to the angle of internal friction, and the intercept with the \(y\)-axis represents the cohesion.  
A comparison of the shear strength parameters of the consolidated soil with those of untreated soil revealed a significant improvement in both cohesion and the angle of internal friction. This improvement demonstrates the effectiveness of the composite dust suppressant in enhancing the shear performance of the soil.  
The enhanced shear performance of the consolidated soil has important implications for soil stability and engineering applications. The increased shear strength and improved resistance to shear deformation contribute to the overall stability of soil structures, such as embankments, road bases, and landfills, making them more resilient to external loads and environmental factors.  
Figure 4: Shear performance test results. The red and black dots are the vertical pressure relationships between the solidified soil and the control group, respectively. (**a**) Stress-displacement curve of dust suppression agent treatment group of C1, C2, C3 and C4. (**b**) Relation between shear strength and vertical pressure.  
In summary, the direct shear tests conducted on consolidated soil treated with the composite dust suppressant have shown a significant improvement in shear performance. The increased shear strength, cohesion, and angle of internal friction demonstrate the effectiveness of the treatment in enhancing soil stability and resistance to shear forces. These findings provide valuable insights for the design and construction of soil structures in various engineering applications.