# Research Progress on the Mechanisms and Control Methods of Rockbursts under Water-Rock Interactions
## 3 Research Progress on Water's Impact in Strain-Induced Rockburst Experiments
### Study on the Mechanical Properties of Sandstone under Wet-Dry Cyclic Conditions  
Studying the mechanical properties of sandstone under wet-dry cyclic conditions is important because these conditions are commonly encountered in natural environments. Wet-dry cycles can induce stress and strain within sandstone, affecting its mechanical properties [65; 66; 67]. Common wet-dry cycle conditions include humid and arid climates, as well as variations in groundwater levels. In this field, scientists often use experimental techniques to evaluate the physical properties of sandstone, including dynamic elastic modulus, tensile strength, and compressive strength, under different wet-dry cyclic conditions. They also explore the rock's fracture behavior and damage mechanisms [67; 68; 69]. Common experimental techniques include dynamic tensile tests, compression tests, and digital image correlation [70]. These studies are essential for grasping how wet-dry cycles affect the mechanical properties of geological materials in natural environments. They offer important insights that are beneficial for engineering design and applications in related fields. [PERSON] et al. [56] investigated through experiments and numerical simulations how wet-dry cycles lead to reductions in the strength, stiffness, and toughness of sandstone, as well as alterations in its fracture behavior and damage mechanisms. The study revealed that wet-dry cycles cause the expansion and contraction of pore water within the sandstone, resulting in changes in internal stress, which in turn leads to the propagation and aggregation of microcracks, ultimately forming macroracks. Additionally, [PERSON] et al. [56] investigated how wet-dry cycles influence the fracture behavior and damage mechanisms of various sandstone types. [PERSON] et al. [68; 69] studied the effects of these cycles on the dynamic tensile and compressive properties of sandstone. Their findings revealed that repeated wet-dry cycles markedly decrease both dynamic tensile and compressive strengths, while also affecting deformation behavior. These results are crucial for understanding the stability of rock structures in natural and engineering settings. The three referenced studies collectively examine the mechanical properties of sandstone under wet and dry cyclic conditions [67; 68; 69]. These studies provide valuable references for further research in the field, though they differ slightly in focus and methodology. The following provides a detailed explanation:  
1. Similarities: 1. All the studies concentrate on the mechanical properties of sandstone subjected to wet and dry cyclic conditions;* All utilize experimental techniques to assess the dynamic tensile or compressive properties of sandstone;
* All findings indicate that wet and dry cycles have a significant impact on the mechanical properties of sandstone. * [PERSON] et al. [56] focus more on the fracture behavior and damage mechanisms of sandstone under wet and dry cyclic conditions, while the other two studies place greater emphasis on its dynamic tensile or compressive properties;
* [PERSON] et al. [68] primarily test the dynamic tensile properties of sandstone, whereas [PERSON] et al. [69] focus mainly on its dynamic compressive properties. * The experimental methods used in the three studies differ slightly. For example, [PERSON] et al. [56] employed digital image correlation to investigate sandstone's fracture behavior, while the other two studies used different testing equipment and methods. [PERSON] et al. [68] employed a dynamic tensile testing machine to evaluate the dynamic elastic modulus and tensile strength of sandstone under wet and dry cyclic conditions. This approach uses dynamic loads to replicate the stress conditions sandstone experiences in natural settings. In contrast, [PERSON] et al. [69] utilized a compression testing machine to measure the compressive strength, dynamic elastic modulus, and Poisson's ratio of sandstone under similar cyclic conditions.