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The mechanical rock bolt is a new type of prestressed anchor bolt ingeniously combined with rock anchor bolts and end expansion shells. After the installation of the expansion shell grouting anchor bolt, the prestress is immediately provided by the opening of the steel expansion shell anchor fasteners, which can effectively control the loosening and deformation of the surrounding rock in a timely manner and promote the formation of a compressive stress ring in the surrounding rock within the anchoring range, further enhancing the reinforcement effect of the anchor bolt on the surrounding rock and the stability of the project.
| Anchor Bolt Body | Mechanical Anchor Fasteners | ||||
| Diameter | Lower Yield Force | Maximum Force | Total Elongation at Maximum Force | Ultimate Bearing Capacity | Applicable Anchor Hole Diameter |
| 25mm | ≥150kN | ≥200kN | ≥5% | ≥84kN | 40-45mm |
| 32mm | ≥280kN | ≥360kN | ≥126kN | 51-56mm | |
| 38mm | ≥400kN | ≥500kN | ≥196kN | 65-70mm | |
| 51mm | ≥630kN | ≥800kN | ≥260kN | 76-90mm | |
The expansion shell type prestressed hollow grouting anchor bolt should be composed of a hollow rod body, steel expansion shell anchor fasteners, grouting plugs, grouting pipes, spacers and hexagonal nuts.
The expansion shell anchor head adopts a mechanical structure. Through tensioning and locking, it can immediately generate support force, quickly clamp the rock mass, and help form a pressure arch, thereby effectively suppressing the loosening of the surrounding rock.
This anchor bolt system provides an initial prestress of 60kN to 150kN through tensioning in the early stage, forming active support, and the single-anchor bearing capacity of the anchor bolt is ≤200KN ; In the later stage, it was transformed into a passive support mechanism of full-length anchoring through full-length grouting bonding. This combination method not only allows the surrounding rock to undergo moderate deformation but also fully exploits its self-supporting capacity, providing a reliable technical guarantee for the stability of the surrounding rock.
The rods can be inserted first, and then the prestress is applied before grouting. The grout flows from the bottom end to the head of the anchor rod through the hollow steel pipe, which can ensure the grouting is full.
The prestressed expansion shell grouting anchor bolt can effectively maintain the overall stability of the broken rock layer after excavation by applying sufficient prestress and full-length bonding support, avoiding instability or even collapse of the surrounding rock, and has good anchoring effect and durability.
Expansion shell grouting anchor rods are used in underground projects in high-stress rock strata where rockburst occurs.
The expansion shell grouting anchor bolt effectively maintains the overall stability of the fractured rock layer.
Expansion shell grouting anchor rods are used for anchoring support projects where the strata are hard rock or medium-hard rock.
