학술논문
氯盐环境下螺纹钢锚杆力学性能退化研究 / Study on the Degradation of Mechanical Properties of Threaded Steel Bolts in Chloride Environment
Document Type
Academic Journal
Author
Source
金属矿山 / Metal Mine. (12):76-85
Subject
Language
Chinese
ISSN
1001-1250
Abstract
锚杆支护作为目前高效支护方式之一,广泛用于岩土工程领域.为解决岩土体中锚固结构过早失效的问题,以工程中常用的HRB400 螺纹钢锚杆为研究对象,在盐雾试验箱中进行 3～50 d的室内试验,结合静力拉伸试验和扫描电镜等宏微观手段研究其在氯盐腐蚀环境下的耐久性能,并结合开挖补偿理论与数值分析,研究巷道支护锚杆受到腐蚀后对围岩稳定性的影响.结果表明:氯盐腐蚀环境下随着时间增加,锚杆表面逐渐产生明显的腐蚀坑,质量损失率与腐蚀速率呈负相关关系;锚杆的抗拉强度、屈服强度等力学性能随时间增长整体呈下降趋势,但仍在一定时间内保持良好性能.锚杆断口韧窝尺寸呈小而浅的特征,且数量密集,是锚杆韧性下降的表现.结合开挖补偿理论分析发现在长期腐蚀环境下,腐蚀会对锚杆力学性能产生较大影响,使巷道围岩产生应力集中,剪切应力增大,失去支护效果.当支护效果减弱时,巷道两帮应力集中现象最明显,塑性区会沿着顶底角方向发展,对于巷道两帮应加强支护.
As one of the efficient support methods,anchor rod support is widely used in geotechnical engineering.In order to solve the problem of premature failure of anchorage structures in rock and soil mass,the commonly used HRB400 thread steel anchor rods were subjected to indoor tests in salt spray test chambers for 3～50 d.The durability performance of the an-chor rods under chloride salt corrosion environment was studied by combining macro and micro means such as static tensile tests and scanning electron microscopy,combined with excavation compensation theory and numerical analysis to study the sta-bility of the roadway support anchor rods on the surrounding rock after being subjected to corrosion.The results show that the surface of anchor rods gradually produced obvious corrosion pits with the increase of time under the chloride salt corrosion envi-ronment,and the mass loss rate was negatively correlated with the corrosion rate.The mechanical properties of anchor rods such as tensile strength and yield strength showed an overall decreasing trend with the increase of time,but still maintained good performance within a certain period of time.The tough nest size of anchor rod fracture is characterized by small and shallow,and the number is dense,which is a manifestation of the decrease of anchor rod toughness.Combined with the excavation com-pensation theory analysis found that in the long-term corrosive environment,corrosion will have a greater impact on the mechan-ical properties of anchor rods,resulting in stress concentration in the roadway envelope,increased shear stress and loss of sup-port effect.When the support effect is weakened,the stress concentration phenomenon is most obvious in the sides of the road-way,and the plastic zone will develop along the top and bottom corners,so the sides of the roadway should be strengthened.
As one of the efficient support methods,anchor rod support is widely used in geotechnical engineering.In order to solve the problem of premature failure of anchorage structures in rock and soil mass,the commonly used HRB400 thread steel anchor rods were subjected to indoor tests in salt spray test chambers for 3～50 d.The durability performance of the an-chor rods under chloride salt corrosion environment was studied by combining macro and micro means such as static tensile tests and scanning electron microscopy,combined with excavation compensation theory and numerical analysis to study the sta-bility of the roadway support anchor rods on the surrounding rock after being subjected to corrosion.The results show that the surface of anchor rods gradually produced obvious corrosion pits with the increase of time under the chloride salt corrosion envi-ronment,and the mass loss rate was negatively correlated with the corrosion rate.The mechanical properties of anchor rods such as tensile strength and yield strength showed an overall decreasing trend with the increase of time,but still maintained good performance within a certain period of time.The tough nest size of anchor rod fracture is characterized by small and shallow,and the number is dense,which is a manifestation of the decrease of anchor rod toughness.Combined with the excavation com-pensation theory analysis found that in the long-term corrosive environment,corrosion will have a greater impact on the mechan-ical properties of anchor rods,resulting in stress concentration in the roadway envelope,increased shear stress and loss of sup-port effect.When the support effect is weakened,the stress concentration phenomenon is most obvious in the sides of the road-way,and the plastic zone will develop along the top and bottom corners,so the sides of the roadway should be strengthened.