## 2 Case of Mud Inrush Disaster
### Disaster-Causing Factors of Mud Intrush Disasters
#### 2.3.2 Hydrologic Factors  
1. Climate  
As mentioned previously, the groundwater that drives the mud inrush disasters is primarily supplied by rainfall, which is closely linked to climate conditions. Therefore, the occurrence of these disasters is inherently connected to the climate. For instance, during rainy seasons, continuous heavy rainfall can cause the groundwater level and hydrostatic pressure to rise continuously. As a result, a significant amount of energy can accumulate in the fault zone, potentially leading to catastrophic disasters. Conversely, if the tunnel construction takes place during dry seasons when evaporation exceeds recharge, there may not be enough groundwater to trigger the disasters. 2. Groundwater pressure  
The groundwater pressure, encompassing both hydrostatic pressure and dynamic water pressure, serves as the driving force for mud inrush disasters. The hydrostatic pressure gradually compresses the surrounding rocks, resulting in the accumulation of stress energy over time. Additionally, the fissures and pores within the rocks may expand under the compressive stress, facilitating groundwater seepage. Moreover, the dynamic water pressure exerts both impact force and drag force on the surrounding rocks. The impact force weakens the strength of the rocks, making them more susceptible to deformation and failure. The drag force, on the other hand, enables the transfer of rock particles along with the flowing groundwater. In essence, the groundwater pressure contributes to the accumulation of energy, expansion of channels, and migration of particles, all of which have a profound effect on the occurrence of mud inrush disasters. 3. Chemical properties of groundwater  
The chemical properties of groundwater, including iron exchange, dissolution, hydration, and hydrolysis, can significantly impact the mineral composition of surrounding rocks. Such chemical actions can result in altered mineral compositions, leading to changes in the structure of the rocks, which in turn affect their strength and stability. As a result, there exists a close relationship between the chemical properties of groundwater and the occurrence of mud inrush disasters. 2.3.3. Human Factors  
1. Survey and design  
Due to limitations in survey technologies or instruments, it is possible that some crucial engineering geological information may not be accurately acquired during the actual engineering process. This can result in potentially unreasonable tunnel designs. In such cases, there is a high likelihood of mud inrush disasters occurring if the tunnel is constructed without proper consideration of the accurate engineering geological information. The lack of detailed geological survey during the early stages was an important factor in the disaster's occurrence. 2. Construction method  
During the tunnel construction process, excavation disturbances can cause deformations in the surrounding rocks, leading to potential instability and triggering geological hazards. However, the use of appropriate excavation methods can partially reduce these disturbances, and suitable support methods can resist large deformations, thereby enhancing the stability and bearing capacity of the surrounding rocks. As a result, the probability of disasters can be effectively reduced by adopting proper construction methods that take into consideration the actual geological characteristics. 3. Theoretical Analysis of the Disaster-Causing Factors  
Indeed, the mud inrush disaster is influenced by various factors as discussed previously, and the contribution of each factor may vary significantly. It may not be feasible to consider all factors comprehensively in practical engineering, especially in the context of disaster treatment. Therefore, a key task in further research, including the study of catastrophic mechanisms and disaster treatment, is to clarify the relative importance of these factors. Quantitative evaluation and ranking of the disaster-causing factors based on their individual significance can help in achieving this objective.