Rock Bolt Anchor Arrangement for Dynamic Shock Load Absorption
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Solution Overview
Problem
Existing rock bolts do not effectively absorb shock loads during dynamic rock displacement events, such as seismic activity, and may fail to maintain sufficient anchorage under varying rock displacement conditions.
Innovation Solution
A rock bolt with an elongate tube and an expander mechanism that allows for two modes of operation: a first mode where the anchor arrangement moves away from the trailing end to expand and absorb shock, and a second mode where it couples to the tube to share tensile load, enhancing anchorage and shock absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anchor arrangement is fixed to the tube (prior art design), then the structure is simple and manufacturing is easier, but the rock bolt cannot absorb shock loads during dynamic rock displacement events
Solution Approach 1:
The anchor arrangement is designed to be movable relative to the tube along the longitudinal axis, transitioning between a first position for shock absorption and a second position for load sharing. This dynamic capability allows the rock bolt to adapt to different loading conditions, absorbing seismic shocks when in the first position and sharing tensile loads with the tube when in the second position, thereby resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The anchor arrangement is divided into separable components including the couple, rock plate, and tube, allowing independent movement and function. The couple can detach from the tube and re-engage, enabling the system to absorb shock loads through relative movement while maintaining structural integrity during normal operation, thus improving reliability without excessive complexity.
2Reliability
If the expander mechanism expands fully during installation, then anchorage is maximized, but further expansion is prevented during rock displacement reducing shock absorption
Solution Approach 1:
The expander mechanism is designed with dynamic expansion capability that allows it to be fully expanded during installation for maximum anchorage, then further expand during rock displacement events. The movable anchor arrangement enables this progressive expansion by allowing the couple to move away from the tube, creating space for additional expander mechanism expansion and thereby improving both anchorage strength and adaptability to varying conditions.
Solution Approach 2:
The expander mechanism is preliminarily expanded during installation to establish initial anchorage, but the design anticipates future rock displacement events by allowing further expansion. The movable anchor arrangement is pre-configured to enable this additional expansion, ensuring the system can respond to varying rock displacement conditions while maintaining strong initial anchorage.
3Reliability
If the tendon remains connected between expander mechanism and anchor arrangement during actuation, then load transfer is continuous, but the anchor arrangement cannot move to allow further expansion
Solution Approach 1:
The tendon is designed with dynamic connection capability that maintains continuous load transfer while allowing the anchor arrangement to move relative to the tube. The tendon can accommodate the movement between the first and second positions of the anchor arrangement, enabling both continuous load transfer and further expansion of the expander mechanism during rock displacement, thus resolving the contradiction between load transfer continuity and expansion capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The rock bolt effectively absorbs shock loads during dynamic events and maintains strong anchorage by adjusting its operational mode to accommodate varying rock displacement conditions, improving stability and support.
Implementation Method 1
the tube frictionally engages the facing wall or surface of the hole along the length of the tube once the tube is inserted
Implementation Method 2
The expander mechanism is activated once the rock bolt has been inserted into the hole and increases the frictional engagement of the tube with the facing wall of the hole
Implementation Method 3
The rock plate applies a compressive force to the rock face which resists displacement of the rock strata
Implementation Method 4
allowing further expansion of the expander mechanism (if possible) and allowing elongation of the rod
Data Source
Figure 1
Figure 2~4
Figure 5~8
AI summary
A rock bolt 10 comprising: an elongate, generally circular tube 12, the tube 12 having a leading end 14 and a trailing end 16, an expander mechanism 18 disposed within the tube 12 in the region of the leading end 14, an elongate tendon 28 disposed longitudinally within the tube 12 and in connection at or towards a first end 26 of the tendon 28 with the expander mechanism 18 and in connection at or towards a second 38 and opposite end of the tendon 28 with an anchor arrangement 30 positioned at the trailing end 16 of the tube 12, the tendon 28 being actuatable to actuate the expander mechanism 18 and to remain connected between the expander mechanism 18 and the anchor arrangement 30 while the expander mechanism 18 is actuated, wherein the anchor arrangement 30 includes a couple 44, 54, 66 which, under tensile loading of the tendon 28, has a first mode of operation that allows movement of the anchor arrangement 30 axially away from the trailing end 16 of the tube 12 and enabling further expansion of the expander mechanism 18, and a second mode of operation that couples the anchor arrangement 30 to the tube 12 preventing further movement of the anchor arrangement 30 axially away from the trailing end 16 of the tube 12.