## 5 Conclusions  
The microscopic damage process of red-bed soft rock is fully revealed through the study of the interfacial evolution kinetic model of red-bed soft rock, which provides a new idea for the quantitative study of water-rock damage in red-bed soft rock. The degree of damage to this type of rock can be predicted by the change in the solution ion concentration. By applying fractal theory to the description of fracture extension in red-bed soft rock, the stage of fracture development can be predicted, which in turn facilitates the prediction and prevention of red-bed geologic disasters. The following paragraphs present the conclusions of this paper. The micro-interfacial effect of the red-bed soft rock is primarily evidenced by the softening effect of water on the filler between the particles. This transforms the tiny solid particles into flocculent particles, which gradually dissolve in the water. This process results in the expansion of tiny fractures and an increase in porosity. In essence, the microscopic damage of soft rock is the evolutionary process of the dissolution and detachment of its internal soluble joint structure. The 3D fractures were quantitatively analyzed using multiple fractal theory. In the early stage of water saturation, water exerts a greater impact on the damage of the red-bed soft rock. This is evidenced by the emergence of disorganized pores and fractures in the  
Figure 11: Parameter fitting of the kinetic model of interface evolution. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Element** & \(D_{e}\) & _r/(cm)_ & \(C_{1}\)**/(\(\upg\cdot\)mL\({}^{-1}\))** & \(C_{0}\)**/(\(\upg\cdot\)mL\({}^{-1}\))** & \(\mathbf{R^{2}}\) \\ \hline Al & 0.25 & 5 & 1.8 & \(1.5\times 10^{-13}\) & 0.9932 \\ Ca & 0.26 & 0.5 & 2.46 & \(1.07\times 10^{-18}\) & 0.9751 \\ Fe & 0.29 & 5 & 2.28 & \(1.35\times 10^{-11}\) & 0.9887 \\ Mg & 0.24 & 5 & 0.3 & \(1.52\times 10^{-17}\) & 0.9764 \\ Na & 0.25 & 7.4 & 1.74 & \(2.02\times 10^{-14}\) & 0.9812 \\ Si & 0.24 & 3.6 & 3.42 & \(2.19\times 10^{-2}\) & 0.9928 \\ \hline \end{tabular}
\end{table} 
Table 3: Microkinetic model parameter fitting results. natural state of the red-bed soft rock, which leads to a dramatic increase in the fractal dimension of the rock. As the saturation time continues to increase, the internal pores begin to reorganize and connect, the soft rock specimens accelerate the damage and the rate of fracture development exceeds the rate of new pore generation. Concurrently, the orientation and distribution of the fractures exhibit some self-similarity, resulting in a decrease in the 3D fractal dimension. It is established that hydrodynamic pressure and hydrostatic pressure cause damage to soft rock. Hydrodynamic pressure is defined as the pressure generated by water flow and infiltration at the early stage of water saturation, when the rock mass is still unsaturated. This pressure generates infiltration pressure on the large particles around the channel in the same direction as the flow direction (tangential thrust). The direction of hydrostatic pressure is a positive stress perpendicular to the water-rock interface, situated between the granular skeletons of the tiny particles. This causes the tiny pores to be subjected to an outward expansion force. This force, perpendicular to the pore walls, causes the pores to expand under force. The change in ion concentration in the solution of red-bed soft rock under different water saturation times has been observed to result in the precipitation of a significant number of ions from the red-bed soft rock during water-rock interaction. Based on the principles of diffusion theory, this study proposes a kinetic model for the evolution of the micro-interface of red-bed soft rock. This model is capable of accurately describing the nonlinear ion change rule of the micro-interface of the red-bed water-rock interaction, and it is able to fit the calculated value with the measured value to a high degree of accuracy.