Abstract: A cable bolt comprises a cable with a tubular yielding fixture at one of its ends. The pull-off load of such yielding fixture can be adjusted to a desired value. This is achieved by unwinding one end of the cable and inserting a slug over the kingwire. Then, the peripheral wires are wound again over the kingwire forming a bulge in the cable where the slug is located. The yielding fixture is then slid on the cable and forced over the bulged portion of the cable, while measuring the load required to achieve this operation, which also becomes the pull-off load of the yielding fixture. Finally, any part of the cable protruding from the fixture is cut-off to form the cable bolt with the desired yielding fixture at its end.

Abstract: A cable bolt comprises a cable with a tubular yielding fixture at one of its ends. The pull-off load of such yielding fixture can be adjusted to a desired value. This is achieved by unwinding one end of the cable and inserting a slug over the kingwire. Then, the peripheral wires are wound again over the kingwire forming a bulge in the cable where the slug is located. The yielding fixture is then slid on the cable and forced over the bulged portion of the cable, while measuring the load required to achieve this operation, which also becomes the pull-off load of the yielding fixture. Finally, any part of the cable protruding from the fixture is cut-off to form the cable bolt with the desired yielding fixture at its end.

Abstract: A stress measuring rock support device is provided, such as a cable bolt or friction stabilizer, which has an internal longitudinal cavity, such as a groove or a flat section on the kingwire or a hollow core in the kingwire or the like. One or more rigid wires or filaments extend in such cavity and their ends are anchored at predetermined anchor points within the cavity. The other ends of the rigid wires or filaments are spring-loaded and are provided with movable actuators having electrical contacts which are in contact with a linear potentiometer and measure the displacement of the actuators resulting from the stretch of the cable. This is then correlated to measure the cable load or strain resulting from the stress applied to the rock support device. The spring-loaded arrangement as well as the linear potentiometer and the actuators with electrical contacts are enclosed within a suitable cover to form an instrumentation head assembly for the rock support device.