The need for and scope of application of stainless steel rock bolts

Corrosion wear of the rock bolt elements with loss of their bearing capacity is sometimes observed in operation of the rock bolt support. Studies carried out in the mine workings secured with resin grouted rebar bolts allowed us to determine the patterns of corrosion wear of the rock bolt elements and measures to prevent it. Development of the rock bolt element corrosion is observed when they are moistened. The probability of free water content in the roof rocks increases with the growth of rock fracturing. The rate of the corrosion process increases with a decrease in the hydrogen index of water. Analysis of possible ways to prevent rock bolt support failures caused by the corrosion wear revealed that the most economical of them is the application of anti-corrosion coatings on the rock bolt support elements. Technical requirements were developed for the means of anti-corrosion protection of the metal rock bolt supports, they were selected among the anti-corrosion means available in the market of the Russian Federation, and their mine tests were carried out as the anti-corrosion coatings of the rock bolts in the most aggressive mine environment. According to the results of the mine tests, one anti-corrosion medium was identified that successfully passed the tests. The anti-corrosion coating created with this medium did not fail, corrosion failure of the rock bolt support elements was not observed. According to the test results, it was concluded that the anti-corrosion coating can prevent the failure of the rock bolt support operation. The field of application for stainless rock bolts is mine workings with long service life of the rock bolt support when the roof rocks are saturated water which pH < 7. The economic effect of using the rock bolts with anti-corrosion coating would amount to 6.6 million rubles/km. On average, only 4.2% of the rock bolts supplied to mines should have an anti-corrosion coating. It is possible to predict the need for the use of stainless rock bolts before driving the mine working, which will allow determining the necessary volume of their purchase in advance.