# Study of the Failure Mechanism of Soft Rock Mining Roadways Based on Limit Analysis Theory
## 2 Analysis of the Deformation and Failure of a Soft Rock Mining Roadway
### Physical Similarity Simulation Experiment Verification
#### 3.2.4 Analysis of the Failure Mechanism of the Rock Surrounding Soft Rock Mining Roadways  
1. Due to stress concentration, shear failure occurs first in the sidewall of the roadway. The crack extends along the blind support area (area C) above the bottom angle of the roadway. Finally, an arc-shaped shear slip fracture is formed inside the two sides of the roadway, resulting in the failure of the middle and upper bolts. 2. With the increase in surrounding rock pressure, the fracture in the roadway side continues to expand to the blind support area of the direct roof (area C) and low-strength support area (area B) above the slope. The formation of arc-shaped shear slip cracks occurs. Crack propagation further weakens the support strength of the angled anchor cable in the roadway shoulder, which increases the direct roof failure range. 3. When the crack penetrates the interface between the direct roof and the main roof, the extension direction of the crack changes notably. The failure mode of the crack also changes from slip shear failure to tensile failure, and the cracks in the basic roof expand in zone E. The opening degree of the macroscopic cracks on the two sides of the roadway increases, and the displacement shows a significant increasing trend. The floor of the roadway bends and deforms toward the free surface, tensile cracks are generated on the surface of the floor, separation cracks are generated between the layers, and the range of fracturing in the floor gradually extends downward. 4. With increasing surrounding rock pressure, the original microcracks extend and connect with each other and finally transform into macroscopic shear slip surfaces. Multiple slip surfaces combine to form a shear slip band (zone E). Under the action of the self-weight of the block in the slip plane (zone D) and the roof pressure, the status of the rock mass in the shear slip zone (zone E) and its inner anchored rock mass (zone D) changes from static to dynamic. At the same time, the width of the shear slip zone shows an increasing trend, and the cracks expand into the anchorage zone (zone D) of the anchor cable. This causes the risk of failure of the anchorage system. The  
Figure 10: Failure characteristics of roadway-adjacent rock (\(\sigma_{\rm s}\) = 13.5 MPa). (**a**) Experiment photograph; (**b**) sketch. roof movement causes the anchor body of the roadway side to slip, resulting in the coal bulging from the roadway side. Additionally, the sliding of the roadway side block also drives the overall subsidence of the roof sliding block, the deformation and failure of the floor, and the contraction of the roadway section. This paper takes the 1506 return airway of Anyang Coal Mine as the research object and discusses its damage mode and damage range. This work represents a powerful supplement to the existing research on the damage problem of soft rock mining roadways and makes up for the shortcomings in existing research to a certain extent. Additionally, it can also provide the necessary reference basis for research on soft rock roadways. The results of this study mainly reveal two findings. One is that the damage mode of soft rock mining roadways consists of a series of rigid sliders. The second is that the damage range of soft rock mining roadways is related to several factors. Consequently, we should not only pay attention to the selection of the damage mode but also consider the influence of various factors on the damage range of the roadway to ensure the accuracy of roadway damage research. Compared with existing research results, the insights presented in this paper have both similarities and differences. In terms of commonalities, the choice of the damage mode of the roadway perimeter rock to carry out research on the roadway gang part and roof partition is still based on certain assumptions.