Document Type

Conference Paper

Publication Date


Publication Details

Naj Aziz, Ali Mirza, Jan Nemcik, Xuwei Li, Haleh Rasekh and Gaofeng Wang, Load Transfer Characteristics of Plain and Spiral Cable Bolts Tested in New Non Rotating Pull Testing Apparatus, in Naj Aziz and Bob Kininmonth (eds.), Proceedings of the 16th Coal Operators' Conference, Mining Engineering, University of Wollongong, 10-12 February 2016, 32-39.


The load transfer mechanisms of cable bolts differ from normal rebar bolts. Cable bolts used in mines are basically steel strands with different constructions depending on the number of wires or elements and the way that these elements are laid. Tendon bolts (rebar and cable) are normally evaluated for strength and load transfer properties. The strength of tendon can be carried out by tensile failure tests, while the load transfer strength is evaluated by pull and shear strength tests. Short Encapsulation Pull Testing (SEPT) is used to study of the load transfer capacities of tendons, and can be undertaken both in the laboratory and in situ. A new apparatus known as Minova Axially Split Embedment Apparatus (MASEA) was used to study load-displacement characteristics of smooth versus spiral profile cable bolts. Minova Stratabinder grout was used for encapsulating 400 mm long 19 wire 22 mm diameter superstrand cable in the embedment units. The anchorage of the cable on two sides of the embedment apparatus were intentionally installed at different lengths, to allow the cable to be pulled out from one side of the anchorage. The spiral wire strand cable bolts achieved higher peak pull-out load at minimum displacement in comparison with smooth surface wire strand. The peak pull out force increased with the age of encapsulation grout. The MASEA was easier to assemble and test at a short period of time, thus allowing quick and repeated tests to be undertaken.