深井高应力腐蚀环境下锚杆强度劣化机理及预测

Mechanism and prediction of anchor rod strength degradation with deep mine high-stress corrosion environment

  • 摘要: 煤矿深部开采除了面临“三高一扰动”之外,还面临井下腐蚀性大气和高应力、强扰动等因素共同形成的高应力腐蚀环境,井下大气腐蚀环境等级能达到CX(极高腐蚀)级。以山东巨野煤田深部矿井为工程背景,首先分析了深井开采高应力腐蚀特征及影响因素,对锚杆杆体材料开展实验和理论研究,揭示了高应力腐蚀环境下锚杆强度劣化机理,推导了杆体强度劣化理论模型。① 通过对杆体材料开展SEM、腐蚀SSRT和加速腐蚀实验发现:腐蚀会造成杆体材料的断后伸长率和断裂时间的衰减,相较于惰性条件分别减少了8.22%和8.34%;随腐蚀率增加,材料破坏形式由韧性破坏向脆性破坏转变,区域腐蚀类型逐渐由点蚀发展为均匀腐蚀。② 结合实验结果、电化学理论与非均匀腐蚀模型,引入Pruckenr温度影响因子,推导出杆体材料强度劣化时变模型。深入探究该模型中服役环境温度T、杆体截面半径R和杆体材料常温腐蚀速率Vh,298K对杆体服役寿命的影响发现,R与服役寿命呈线性正相关;TVh,298K与服役寿命的关系表现为服役寿命衰减程度随影响因素水平升高而减小。③ 结合实验结果与锚杆防冲吸能原理,对巷道锚杆支护极限抗冲能力进行计算分析。结果表明,随锚杆腐蚀率增加,锚杆吸能减少,可抵抗最大震级降低,巷道动力失稳灾害发生风险增加。

     

    Abstract: Deep coal mining, in addition to facing the three “high” and one “disturbance”, faces a high-stress corrosion environment formed by underground corrosive atmosphere, high stress, strong disturbance, and other factors. Taking the deep mines in the Juye Coalfield, Shandong, as the engineering background, the high-stress corrosion characteristics and influencing factors of deep mining are analyzed. Experimental and theoretical research is conducted on the anchor rod material to reveal the degradation mechanism of anchor rod strength under high-stress corrosion environment, and a theoretical model for the degradation of rod strength is derived. The results are as follows: ① through the SEM, corrosion SSRT, and accelerated corrosion experiments on rod materials, it is found that the corrosion causes a decrease in the elongation at break and fracture time of rod materials by 8.22% and 8.34%, respectively, compared to inert conditions. With the increase of corrosion rate, the material failure mode transitions from ductile to brittle fracture, and the localized corrosion type gradually evolves from pitting to uniform corrosion. ② Combining experimental results with electrochemical theory and non-uniform corrosion models, introducing the Pruckenr temperature influence factor, a time-varying model for the degradation of rod material strength is derived. The in-depth investigation of the impact of service environment temperature T, rod cross-sectional radius R, and material room temperature corrosion rate Vh,298K on the service life of the rod reveals that R is linearly positively correlated with service life. The relationship between T and Vh,298K with service life shows that the degree of service life decay decreases as the levels of influencing factors increase. ③ Combining experimental results with the energy absorption principle of anchor rods, the limit energy absorption capacity of roadway anchor rod support is calculated and analyzed. The results show that as the corrosion rate of the anchor rod increases, the energy absorption of the anchor rod decreases, the maximum seismic resistance decreases, and the risk of roadway dynamic instability disasters increases.

     

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