Study on Mechanical Characteristics of Energy-Absorbing and Anti-Scour Bolts

Abstract

In order to improve the impact resistance and mechanical performance of anchor rods and satisfy the requirements for supporting rockburst roadways, the energy balance equation of the energy-absorbing support and roadway surrounding rock system is established. Moreover, to effectively prevent rockburst disasters, the energy criterion for roadway instability is derived. From the perspective of an energy-absorbing support, a yield-absorbing anti-shock anchor composed of a rod body, tray, constant resistance energy-absorbing device, and special-shaped nut is designed and developed; compared with ordinary anchor rods, this rod has stronger mechanical properties for resisting impact. Theoretical and numerical simulation studies show that the energy-absorbing device has a repeatable deformation failure mode and a constant yield force. The paper also presents the principle involved in the design of anti-shock bolt supports. The energy-absorbing support not only effectively guides and controls the release and conversion of impact energy but also consumes the impact energy in the buffering process of the anchor to ensure the stability of surrounding rock and support protection system. This study aims to provide reference for roadway support design and to improve rock bolts used in rockburst roadways.

An Insight from Rock Bolts and Potential Factors Influencing Their Durability and the Long-Term Stability of Deep Rock Tunnels

“…Nevertheless, although it remains a difficult task, there is a great need to accurately estimate the static and dynamic properties of rock bolts. An example of a dynamic impact which can seriously weaken the strength of the bolts is the action of an earthquake [51]. In fact, depending of the total length of the tunnels and their position, they can be exposed to natural earthquakes.…”

Numerical Analysis of Mechanical Characteristics of Constant-Resistance, Energy-Absorbing and Anti-Scour Bolts

“…The conventional anchor rod was 2500 mm long and 20 mm in diameter, the pallet size was 150 × 150 × 10 mm, the diameter of the central round hole was 22 mm, the shaped nut was 38 mm high, the diameter of the thin end was 28 mm, the diameter of the thick end was 48 mm, and the end taper angle was 26.5° ( Figure 2 a). The constant resistance energy-absorbing anchor rod is 2500 mm long and 20 mm in diameter; the shaped nut is 38 mm high, 28 mm in diameter at the thin end, 48 mm in diameter at the thick end, and the end taper angle is 26.5° [ 34 ]; the inner diameter of the anti-puncher is 40 mm, the wall thickness is 4 mm, and the height is 150 mm. The tray size is 150 × 150 × 10 mm, and the diameter of the central round hole is 22 mm ( Figure 2 b).…”

Effects of deflection angle on the mechanical properties of constant-resistance, energy-absorbing, and anti-scouring bolts

“…The new energy-absorbing bolts (cable) have good self-protection and impact adaptability compared with ordinary anchor rods, as shown in the combination static and impact tensile tests. Tang et al (2021) designed a constant-resistance, energy-absorbing, and antiscouring bolt consisting of a rod body, a tray, an antipunching device, and a profiled nut. It was concluded that, under static and impact loads, the indices of the constantresistance, energy-absorbing, and anti-scouring bolts, including yield distance, anti-scour time, and energy absorption, were significantly better than those of the conventional bolts.…”