| 摘要 |
<p>Tube-formed rock bolt with closed profile intended to be anchored in a bore hole. The bolt is anchored in the bore hole through internal pressurisation with a fluid, for instance water, so that its diameter is plastically expanded into contact with the wall of the hole. The bolt has before its expansion a cross-section whose peripheral length exceeds the circumference of the hole but a largest diameter, which is smaller than that of the hole. In order to obtain a profile being sufficiently flexible for expansion and at the same time having a sufficiently large cross-sectional area for the strength the tube has a varying wall thickness in a peripheral direction. This is achieved by making the tube-formed bolt by means of extrusion of an aluminium-based material.</p> |
