Experimental investigation of dynamic response of liquid-filled rock joints with horizontal inclination under stress wave loading

Abstract

In underground rock engineering, the liquid-filled rock joints are inevitably subjected to dynamic disturbances such as earthquakes and blasting. The fluidity of liquids leads to distinct spatial distribution patterns within inclined joints under the influence of gravitational forces, while the motion characteristics of liquids are altered upon encountering stress waves. This study aimed to investigate the dynamic response of liquid-filled rock joints with horizontal inclination when subjected to stress wave loading. The rock joint specimens filled with liquid were prepared using the gouged samples of diorite, polymethyl methacrylate tubes, and glycerol. Experimental tests were conducted using a modified Split Hopkinson Pressure Bar testing system on jointed rock specimens filled with liquid. Three influencing factors, namely, the joint matching coefficient (JMC), liquid content, and viscosity, were considered. The dynamic response of liquid-filled joints was analyzed based on the transmitted energy of stress waves and liquid motion. The results indicated that an increase in JMC of the liquid-filled rock joints leads to a higher transmission of stress wave energy. As the fluid content increases, the transmission energy of high-amplitude, low-frequency stress waves shows a monotonic increase, while that of low-amplitude, high-frequency waves initially remains constant, followed by an increase. When the liquid content is 50%, the transmission of stress wave energy decreases with increasing liquid viscosity. However, when the liquid content is 100%, the transmission energy shows a trend of initially decreasing and then increasing with increasing liquid viscosity. At the joint boundaries, the direction of fluid motion is perpendicular to the horizontal joint plane and upward. Both the drainage capacity of the joint and the intensity of fluid motion diminish with increasing fluid viscosity. These findings provide some valuable insights into the interaction mechanism between stress waves and liquid-filled rock joints, contributing to a deeper understanding of this phenomenon.

Keywords

• stress wave
• liquid-filled
• rock joints
• dynamic response
• transmitted energy
• liquid motion