Axial force-breaking energy accumulation and dissipation evolution and energy absorption protection mechanism of anchor cable wire

The roof anchor cable in deep high stress roadway under the combined action of tension, shear, torsion and so on, could release accumulated strain energy instantaneously, causing the ejection accident due to anchor cable breaking, which seriously affects the safe production of coal mines. Based on the engineering background of the 1421 (3) anchor cable supporting roadway in the Zhangji Mine, the research methods of theoretical analysis, numerical simulation and laboratory test are used to reveal the energy evolution mechanism of anchor cable-surrounding rock and the energy absorption protection mechanism of anchor cable protection device. The results show that the fracture strain energy density of anchor wire is 55 MJ/m³ obtained by uniaxial tensile test and full constitutive model of anchor wire. The ejection energy released by anchor wire is positively correlated with the fracture length, axial force and diameter of anchor wire. According to the numerical simulation, the shear stress is concentrated at 0.6 m from the roof of the anchor cable, and the anchor cable is easy to break and eject. The initial velocity of the anchor cable with a length of 0.8 m is 102 m/s. Through simulation and strength theoretical analysis, the impact load limit of the original anchor cable energy absorption protection device is obtained as 20 m/s, and the impact load limit is increased to 200 m/s by increasing the base wall of the anchor cable protection device, which effectively solves the deflection failure problem of the anchor cable impact protection device. Based on the static tensile test and free fall impact test of the anchor cable protection device, the reliability of the numerical simulation results is verified, and the maximum energy absorption threshold of the protection device is 1189 J. Under the action of impact force, the spring base without protection device has a lateral offset and a shear failure at the bottom of the spring. Increasing the wall protection of the spring base can effectively restrain the base offset, give full play to the tensile energy absorption characteristics of the spring, and prevent the failure of the spring after shear damage. The test results are consistent with the numerical simulation results. The research results provide a reference for the roadway support design of the same specification parameter anchor cable, the ejection and protection of the anchor cable wire drawing breaking.