Modeling the loss of stability and failure of mine shaft tubing supports

Abstract

The structural integrity and deformation reliability of mine shaft units play a crucial role in mining operations. A structural failure can lead to water ingress into the shaft and subsequent flooding. The deformation strength and reliability of a mine shaft depends on the efficiency and accuracy of the tubing support manufacturing process, which consists of several stages. This paper presents the results of numerical modeling of the deformation of a tubing ring under the effect of uneven pressure, which can occur during plugging. The following factors are considered in the modeling: contact interaction between tubing sections, contact interaction between the tubing and concrete, and the influence of the initial stress-strain state of the tubing formed during tightening of bolted connections. The problem is formulated within the framework of elastic-plastic deformation with account of finite strains. Based on the numerical solution, the conditions under which the loss of stability and failure of the tubing ring are possible were determined. A significant dependence was found between the pressure causing tubing failure and the area over which this pressure is distributed. This dependence is not monotonic and reaches a minimum when the applied pressure is distributed over the area of two tubing segments. The pressure in this case is approximately  ≈1.4 MPa, i.e., it is in the range of realistic plugging pressures, which can reach 3 MPa. The obtained dependences allow assessing the feasibility of critical deformation states in tubing support, and they can be used to select optimal plugging modes when constructing mine shafts.