A support system for large ground convergence conditions or burst-pron
e ground must contain holding elements (rockbolts, cable bolts, etc.)
that are strong yet capable of sustaining large deformations, i.e., th
ey must absorb as much energy as possible. Steel wire rope anchored in
a borehole by a friction bolt provides these desired yield characteri
stics if the frictional anchorage is placed deep enough into the rockm
ass, i.e., in non-yielding rock or beyond the expected depth of rock e
jected during a rockburst. Pull-out tests were conducted on wire ropes
anchored by inflated Swellex bolts to assess the feasibility of this
support concept. The test results demonstrate that a Swellex bolt gene
rates a frictional anchorage that allows the wire rope to slide at hig
h loads and to absorb significantly more energy than either a Swellex
bolt alone, or a cement-grouted cable. The rope/friction bolt combinat
ion can be engineered to provide the desired energy absorption and all
owable deformation by varying the installed lengths of the friction bo
lt and the rope. For yielding rope support, the contact length between
the rope and Swellex bolt must be short enough to ensure that the rop
e can slip well before its tensile capacity is reached. A safe maximum
overlap length lj about one metre for the wire rope used in this test
ing When used as support in the back of drifts, a swaged button on the
ropes end must be used to ultimately mobilize the full rope capacity
thereby protecting against gravity-driven falls of ground.