# Study on the Development Rule of Mudstone Cracks in Open-Pit Mine Dumps Improved with Xanthan Gum
## 5 Conclusions  
The slopes of open-pit mine waste dumps are prone to many small cracks under the influence of wet-dry cycles and self-weight. If timely preventive measures are not taken, the slope's stability will be threatened. This paper uses xanthan gum to modify the crack development characteristics of mudstone in open-pit mine waste dumps, and the following conclusions are drawn. 1. The analysis of the specimen images shows that adding XG to mudstone can significantly reduce the area of cracks after drying shrinkage, manifested explicitly in the changes in crack ratio, crack length, and crack width. The modification efficiency index is introduced to evaluate the effect of modification. A quadratic function relationship exists between the specimen's crack ratio and XG's content. When the content of XG is between 0.5% and 2%, the average modification efficiency is positively correlated with the content. After 2%, it shows a negative correlation, with the maximum average modification efficiency reaching 45%. Similarly, although there is no apparent functional relationship between the length and width of the cracks and the content, adding XG can reduce the height and width of the crack development to a certain extent. Among them, the average modification efficiency of the crack length and width with 1.5% content of XG is 46.2% and 26.3%, respectively. 2. Taking the fractal dimension and probability entropy as indicators, the shape of the cracks and the direction of crack development are comprehensively analyzed. A small amount of XG does not affect the complexity of the mudstone crack boundary. As the content of XG increases, the fractal dimension gradually decreases, indicating that a specific content helps improve mudstone permeability. Since the calculation of probability entropy is greatly affected by the image quality and the number of cracks, combined with the actual performance of the specimen cracks, it is found that the addition of XG does not reduce the disorder of crack development. 3. Based on the results of micro-experiments and the properties of XG itself, the modification mechanism of XG affecting the crack development pattern of mudstone is revealed. During the wet-dry cycle, no new substances were produced in the specimen. In the wet state, XG powder dissolves in water to form a viscous XG colloidal solution, which carries fine soil particles to fill the pores between the mudstone particles and adheres to the surface of the soil body through electrostatic bonding and hydrogen bonding. During the drying process, due to the loss of water, the XG colloidal solution gradually transforms into an XG matrix, forming connections and fillings between the mudstone bodies to resist the tension of mudstone water loss and cracking. The transformation between the XG colloidal solution and the filamentous matrix in the wet-dry cycle is stable. In summary, this paper explores the modification efficiency and optimal mixing ratio of XG in improving the crack development pattern of mudstone. It reveals the modification mechanism of XG, which is significant for developing crack prevention technology and the safety of open-pit mine slopes. Future research will consider the use of environmentally friendly waste materials to achieve more sustainable and eco-friendly mudstone modification techniques. Conceptualization, X.Q. ; methodology, X.Q. and R.L. ; software, X.Q. and R.L. ; formal analysis, X.Q. and R.L. ; resources, Y.T. ; data curation, X.Q. ; writing--original draft preparation, X.Q. ; writing--review and editing, W.Z. ; visualization, X.Q. and Y.T. ; supervision, X.L. ; project administration, W.Z. ; funding acquisition, W.Z. and X.L. All authors have read and agreed to the published version of the manuscript. This study was funded by the National Key Research and Development Program of China (2023 YFF1306001), the National Natural Science Foundation of China (Grant No.