# A Review of the Evolution Characteristics and Argillization of Clay Interbeds in Rockslides
## 3 Parameter Changes during the Argillization Process
### Disintegration  
Groundwater action is an indispensable part of the argillization process, and the parent rocks will inevitably soften and disintegrate to a certain extent under its influence. In order to understand the parameter changes during the argillization process, the first step is to understand the change in parameters during the disintegration process. Water acts as a medium, uniformly transmitting pore pressure to both fractures and the pore. And the pore pressure could be passively enlarged due to the swelling action. It could also be used as a lubricating medium to reduce the effective anti-slip force. At the microscopic level, the hydroxide radicals decomposed by water would enter the lattice. The stronger valence bonds would be transformed into OH-OH bonds, which greatly reduces the shear strength of the sandwich. However, it should be noted that the degree of cementation, rather than the composition of minerals, was the primary controlling factor in the process of water-immersion softening failure. Attention should be paid to differentiate them when parameters are considered in laboratory experiments [15]. Nowadays, indoor disintegration and softening tests are mainly carried out by immersing the material in still water. Although a complete simulation of immersion and water loss under natural conditions was not possible, it still had some significant reference value. Through a long-term immersion test, the immersion softening coefficient of mudstone in the reservoir water level fluctuation zone decreased by 10-20% compared with the laboratory results. The amplitude decrease between silty mudstone and mudstone was different. But the softening coefficient all decreased with increased immersion time. And the test data showed a convergent trend, which indicates the timely occurrence of water-rock interaction [14]. Based on the structural change, the disintegration of mudstone was believed to mainly be due to the change in the macroscopic fracture structure and the simultaneous occurrence of rock softening after the mudstone met water [16]. Both of them were closely related to the microstructure of mudstone itself. The disintegration process would be greatly accelerated after undergoing the cycle of immersion-dehydration-reencountering water. In the first three cycles, the degree of deterioration of the internal friction angle was significantly lower than that of the cohesive force. Chemical changes also occur simultaneously and take on a gradual state during the disintegration process [17]. [PERSON] analyzed the saturated softening process of silststone and argillaceous siltstone from the view of the change in chemical composition [18]. The aqueous solution changed from weak alkalinity to acidity in the whole saturation process. And the critical point of water-rock chemistry would be reached when saturated with water for 3 months. Before 3 months, the ion concentration would decrease due to active exchange and adsorption. After 3 months, the ion concentration recovered and began to stabilize due to the gradual weakening of the aforementioned two effects. Longitudinal and transverse wave velocities were obtained from a saturated softening test on Gonghe tunnel shale using an acoustic wave test [19]. A saturated softening equation was deduced, which has significant implications for reducing the disintegration test pattern and duration. To a certain extent, it overcame the difficulty of the softening property being greatly changed due to the different mineral composition and expansion potential, thus avoiding a significant amount of workload. Attention should also be paid to the selection of parameters that describe the characteristics of the argillization process and to select the most \"sensitive\" parameters, such as using fractal dimension to describe the collapsibility of mudstone [20]. The fractal dimension of mudstone disintegration is positively correlated with the initial fragmentation and the number of disintegration cycles.