Corrosion Behavior and Failure Mechanism of Prestressed Rock Bolts (Cables) in the Underground Coal Mine

Abstract

Premature failure of rock bolts (cables) due to stress corrosion cracking (SCC) is a phenomenon that has been reported to occur in the underground environment. In the 1990s, many failure accidents of bolts which occurred in the United Kingdom were caused by SCC [1]. In this study, the corrosion behavior and failure mechanism of rock bolt (cable) samples obtained from the underground coal mine were examined and discussed. Macroscopic observation and weight loss tests were carried out for the bolts’ corrosion characteristics without failure. The results show that the bolts with short service time (1.5–2 yrs) underwent uniform corrosion. However, bolts with longer service time (3–8 yrs) experienced different pitting corrosion degrees. The corroding degree of different parts of bolt samples shows the following decreasing trend: bolt head > bolt end > free section. The absolute corrosion degree increased with the service time, while the corrosion rate was the highest in the early stage and dropped down in the later stage. At the same time, the macro- and micromethods were used to analyse the failure mechanism in the broken cable sample. Failure of one cable sample with a medium service life (6 yrs) was found to be controlled by the SCC. It was induced by long-term action of O, Cl, and S in the surrounding rock environment and resulted in pitting corrosion. The pitting corrosion reduced the outer diameter of the rock cable and its bearing capacity, leading to the final fracture.

Electrochemical Study of Stainless Steel Anchor Bolt Corrosion Initiation in Corrosive Underground Water

“…The coupled effect of stress and corrosion on the anchorage performance of rock bolts was investigated by Wang et al [9], and the authors found that the bonding strength of rock bolts was significantly degraded by the increasing working stress and corrosion time. Similar results were reported by Wang et al [10], and the longer corrosion time could lead to pitting, which reduced the bearing capacity and lifetime of rock bolts. In general, the durability of bolts can be affected by factors such as temperature, material, stress and corrosion time.…”

“…Except for the studies on the failure modes of steel anchorage bolts [1][2][3][4][5][6][7], many studies [7][8][9][10][11] also focused on the factors that influence the corrosion behavior and durability of steel anchorage bolts. Divi et al [8] investigated the effect of temperature on the corrosion properties of different rock bolts and found that severe corrosion was detected for most rock bolts as the temperature reached 90 • C. The effect of thickness of grout cover layer and water-cement ratio of grout on the long-term stabilization of anchored rock slope was reported by Jiang et al [7].…”

Strengthening Device for Improving Shear Performance of Anchor Cable in Rock Support

“…Saadat et al [22] proposed a new cohesive contact model in distinct element codes (PFC 2D) to investigate the mechanical performance of fully grouted rock bolts. Tahmasebinia et al [23,24] and Wang et al [25] established numerical models of shear tests on cable bolts using the commercial ABAQUS finite-element package to study the dynamic and static shear mechanical characteristics of cable bolts. Numerical simulation is an indispensable method for studying the shear mechanical characteristics of cable bolts and can effectively compensate for shortcomings of laboratory experimental research in monitoring the entire process of microscopic failure evolution.…”

Experimental Study on Corrosion of Galfan‐Coated Full‐Locked Coil Ropes in a Natatorium Environment

“…Long-span space structure is one of the important symbols of the development level of national building science and technology. Full-locked coil rope is widely used in long-span space structures because of its high strength, lightweight, and high fatigue strength [1][2][3].…”