地下巷道支护锚杆腐蚀状况调查及力学性能测试

CORROSION INVESTIGATION AND MECHANICAL BEHAVIOR TEST ON SUPPORT OF BOLTS IN underground drift

调查了河南焦作煤矿地下巷道腐蚀环境和现场10a期管缝式锚杆腐蚀状况,对地下水腐蚀物含量、锚杆宏观质量损失和局部坑蚀情况实施了测量,并对锚杆杆体极限承载力和塑性性能进行测试。结果显示:未加任何保护措施的管缝式锚杆腐蚀较为严重,调查样本中的大多数锚杆寿命接近终结;锚杆外表面腐蚀状况以坑蚀为主,而内表面则以近似均匀腐蚀为主;锚杆表面的坑蚀数目、面积和深度等数据均遵循一定的散布规律,且坑蚀口部面积与深度间有内在关联;锚杆表面的坑蚀和穿孔对锚杆杆体力学性能有严重损害,而且锚杆延伸率损失率远大于极限承载力损失率,亦即腐蚀对锚杆塑性的损害程度远大于对其承载力的损害程度,这使得锚杆在发生破坏前难以监测到明显的变形,极易造成突发性事故。

The corrosion environment of an underground drift of one coal mine and the corrosion status of in-situ split-set bolts, which are embedded in the drift for 10 years, have been investigated. The content of the corrosive mass in the underground water, the general mass loss and the local pit corrosion situation of the bolts are tested. The tensile test is carried out to analyze the peak bearing capacity and the plastic behavior. The obtained results are as follows： the corrosion of the split-set bolts without any protection is very serious, and most of the investigated specimens are nearly out of service. The outer corrosion of the bolts is mainly pit corrosion, and the inner corrosion is nearly uniform corrosion. The pit corrosion amount, area, and depth, etc. all follow certain scatter law; moreover, there is an inherent connection between the pitting area and the pitting depth. The pitting corrosion and punches on the bolt surface have great impairment on the mechanical behaviors of bolts. The loss ratio of the elongation percentage of the bolts is much greater than that of the peak bearing capacity, which shows that the impairment of the corrosion on the plasticity of the bolts is more server than that on the bearing capacity of the bolts. Therefore, the deformation of the bolt before its failure is difficulty to be monitored, and emergent hazards will easily happen.