Study on Mechanical Behavior and Mechanism of Sandstone under the Coupling Effect of Water Content and Dynamic Load

Abstract

In the process of underground engineering construction, rock mass often faces the dual influence of dynamic load disturbance and groundwater, it is therefore essential to investigate the mechanical response of the rock mass under the coupling effect of dynamic load disturbance and water content. In this paper, dynamic load impact tests were carried out on sandstone with bullet velocities of 5 m/s, 10 m/s, and 15 m/s and water content of 0, 0.3, 0.6, and 0.9, and the mechanical behavior and mechanism response of water content to sandstone were investigated. The research findings indicate that this study has made significant contributions in quantifying the along grain and trans-grain fractures of microcracks. It has explored the influence of water content and dynamic loading on the strength mechanism of sandstone. It was discovered that the dynamic loading and water content significantly affect the ratio of along grain and trans-grain fractures, thereby influencing the dynamic behavior of sandstone. The findings suggest a negative association between rock strength and water content and that its peak strength rises as the bullet velocity rises. The fracture characteristics of rock are influenced by water content and bullet velocity. The sample’s fracture degree increases with an increase in water content, its particle size distribution map is evident, and there is a positive relation between bullet velocity and fractal dimension. The energy conversion mechanism of the rock is influenced by the water content, as the bullet velocity increases, the absorbed energy density of the rock becomes higher. Furthermore, the correlation between the absorbed energy intensity and density and its fractal dimension is quantified. It is found that energy density and strength are positively correlated. The greater the fractal dimension, the higher the energy density absorbed.

Dynamic mechanical response and failure characteristics of coal and rock under saltwater immersion conditions

“…These microstructures play an important role in determining the macroscopic mechanical behaviour and failure characteristics of the specimen 91 . In addition, distilled water and saline solution can have a significant impact on the microstructure of coal and rock 92 . In summary, characterizing the internal structure and unstable crack propagation characteristics of coal and rock impact failure in a specimen under the action of distilled water and saline solution at the microscopic scale will aid in understanding the failure mechanism of the specimen.…”

“…Specifically, the impact on dry coal and rock is mainly Type I failure caused by tensile stress σ 1 at the crack tip 37 . When the coal or rock is immersed in water, in addition to eroding the solid medium and generating surface film tension to reduce the strength of the specimen, the free water in the crack increases the meniscus effect stress σ 2 , Stephen effect stress σ 3 and Newton internal friction effect σ 4 on the basis of the tip tensile stress σ 1 , thus generating resistance to crack growth under dynamic loading conditions 92 .…”

Experimental Study of the Multiple Fractalisation of Coal and Rock Failure Subjected to the Coupled Effects of Water, Temperature and Dynamic Loads

“…In addition, the dynamic pressure on the top plate of the 14030 working face was evident, and the impact dynamic load effect triggered by the breakage of the top plate occasionally occurred [23]. Coupled with the strongly disturbed work processes present at the working face, the coupled effect of water content and dynamic loads had a significant impact on the mechanical properties of the coal and rock [24]. The test methods follow the regulations of the Rock Dynamics ISRM Committee [25].…”