Способ и устройство определения несущей способности фрикционных анкеров

Abstract

In underground mining, surface reinforcement is a mandatory part of the works. In addition to frame supports, rock bolts and in some cases a combination of the two are now used. The Split Set® friction bolts, referred to as the FRS, i.e. Friction Rock Stabilizers, in the foreign literature, are actively used. More than 11 companies in Russia are currently officially engaged in production of the friction bolts. At the same time, there is a significant difference in the properties of steel used in production of the bolt shafts. Foreign manufacturers recommend the use of steel with the yield strength of 350–400 MPa. This parameter determines the main characteristic of the FRS, i.e. the load-bearing capacity, which can be assessed only after the friction bolt is introduced in the borehole. Until recently, no way has been available to control this parameter of the standard rock bolt. This is explained by the specific feature of the FRS design, i.e. the absence of projecting parts. The load-bearing capacity is determined using specially prepared rock bolts. The purpose of the research was to develop a method and equipment for determining the bearing capacity of the standard FRS bolt using a certified rock bolt tester. The "expanding collet" method of gripping the bolt shaft was adopted. The design of the loading device was based on interpretation of the structural analysis method for mechanical devices. The parametric synthesis of the device elements was carried out on the basis of experimental trials. Experimental and industrial trials of the device confirmed the possibility of determining the load bearing capacity of any FRS bolt. The implementation of the device makes it possible to test the bearing capacity without disturbing the integrity of the excavation and the rock bolt itself.