弱胶结软岩巷道锚索预紧力的研究

Study on Pretension Force of Anchor Cable in Weak Cemented Soft Rock Roadway

为了获取西部矿区弱胶结软岩巷道锚索支护预紧力参数,采用现场调研、理论分析以及现场试验相结合的方法,分析某矿11301回风顺槽锚索破断失效的原因,发现预紧力施加过高造成的让变形量不足是导致锚索拉断的主要原因,相应提出控制锚索变形以及受力的预紧力确定方法,即锚索张拉预紧应保证张拉后允许变形量大于巷道顶板允许下沉量,且应保障锚索受力状态在顶板下沉过程中处于弹性阶段。并以此方法确定了该矿锚索合理的预紧力为200kN,现场应用表明:顺槽掘进后,没有出现锚索拉断的现象,锚索稳定受力最大为370kN,达到屈服强度的79%;顶板最大下沉量为73mm,两帮最大移近量为29 mm,围岩控制效果较好。

In order to obtain the pretension force parameters of bolt-cable support in weak cemented soft rock roadway in western mining area,the methods of field investigation,theoretical analysis and field test were adopted to analyze the failure reason of the anchor cable breakage in 11301 return air roadway of a mine.It was found that insufficient deformation caused by excessive pretension force was the main cause of cable breakage.A pretension force determining method tocontrol the deformation and force of anchor cable was proposed.Namely,the pretension of anchor cable should ensure that the allowable deformation after tension was greater than the allowable subsidence of roadway roof,and the stress state of anchor cable should be in the elastic stage in the process of roof subsidence.With this method,the reasonable pretension force of the anchor cable was determined to be 200 kN.The field application showed that,no breakage of anchor cable occurred after roadway excavation,and the maximum force of anchor cable was 370 kN,reaching 79% of yield strength.Besides,the maximum subsidence of roof was 73 mm,and the maximum approximation of the two sides was 29 mm,with a good control effect of surrounding rock.