采动应力作用下锚杆锚固段荷载分布特征与锚固力波动机理

Prestressed anchorage technique based on bolts is the most extensive and successful ways to control the deformation of surrounding rock in coal mine roadway. However, the mining roadway must experience lead abutment pressure influence of one or several mining face, which bring the bonding material and the surrounding rock formation of the second interface in the anchorage structure sharply destruction. Due to the anchoring force fluctuation, Roof accident has become the most frequently disaster in coal mine accident. Therefore, the research of the bonding effect of anchoring section under the influence of mining stress needs to be performed. This project study friction resistance of the plastic zone of anchoring section、elastic-plastic zone and the bond stress distribution law of the elastic region through the analysis of the characteristics of load distribution in anchoring section using the resin as the binder. The evolution process of bond deterioration of the anchor regions under the influence of mining stress conduct further research and second interface failure mode and the vibrant response characteristic of anchoring force are studied. To reveal the mechanism of anchoring force with the type of step reducing、multi frequency vibration and completely loss etc, technical means of critical anchorage length, reasonable anchorage factor to stabilize the anchoring force, the design method and the project monitoring scheme of full-length prestressed anchorage are put forward. Which provides scientific basis and theoretical support for the long time stability of mining roadway and roof safety.

以锚杆为主的预应力锚固技术是控制煤矿巷道围岩变形最广泛和最成功的手段。然而，回采巷道必须承受一次或数次采面的超前支承压力影响，导致锚固结构中粘结材料与围岩形成的第2界面急剧破坏，引起锚固力波动，进而诱发的顶板事故已成为煤矿事故中最多的灾害。因此，针对采动应力作用下锚杆锚固段黏结效应的研究亟待进行，本课题通过分析以树脂药卷为粘结剂的加长锚锚杆锚固段荷载分布特征，研究锚固段塑性区摩阻力、弹塑性区和弹性区的黏结应力分布规律，进一步研究采动应力作用下锚杆各区域的黏结劣化演变过程、分析第2界面的破坏模式及锚固力跃动响应特征，揭示锚杆锚固力台阶瞬降、多频振荡和锚固力完全丧失等顶板致灾机理，提出临界锚固长度、合理锚固因子等稳定锚杆锚固力的技术手段以及全长预应力锚固的设计方法和工程监测方案，为采动巷道围岩长时稳定和顶板安全提供科学依据和理论支撑。

项目严格按计划任务书完成了研究，得到了预期成果：①设计完善了“预应力锚固综合实验”装置，实现了预应力循环加载正交实验及参数取值；研究了循环载荷作用下预应力锚杆拉拔过程声发射特性，得到了循环加载AE数与预应力动载锚固效应的相应关系。随着循环载荷加载频率的增大，声发射参数中的平均AE率增大，相同路径作用下的AE总数越小，对锚固系统总损伤程程度越小；反之，平均AE率和AE总数变小，抵抗动载破坏的能力越强，预应力为25kN的锚固试件显示出了较好的优越性，能够更好的适应动载工程；②发现锚固力震荡现象的客观存在，分析了锚固体接触单元的三相线剪切-滑移本构模型，依据锚杆拉拔过程中剪切应力峰值的变化，以峰值剪切强度和残余剪切强度为临界点，将锚固体的变形破坏过程分为弹性、剪切滑移和脱粘阶段，结合剪应力-应变关系，推导了临界锚固长度的计算公式和实际取值；③发现了震荡脱黏过程中的应力波动现象，研究了应力波动的关键参数和特征，在千米深井采动作用影响下，60~80kN的锚杆预紧力可以分别控制稳定围岩和中等稳定的围岩变形，在不稳定围岩中，预紧力要达到100 kN才可完全控制围压变形；④研究了采动作用下煤帮锚固段的累次破坏与脱粘阶段特征与演化规律，建立了煤帮预应力锚固单元的体系，提出了巷道预应力锚固的临界长度的实际取值，揭示了煤帮锚杆等效预紧力与控制。锚杆支护对煤体施加预紧力，使煤体从掘巷后的二向应力状态，恢复到三向应力状态，提高煤体的力学性质，使掘巷后的摩尔应力圆远离强度包络线，减小塑性区的宽度，提高巷帮煤体的稳定性。.项目研究期间累计撰写出版了2部学术专著，获得了省部级科研奖励成果一等奖1项、二等奖2项；累计培养教授1名、副教授4名、博士后3人、4人取得博士学位论文、8人取得硕士学位论文，授权国内、国际发明专利11件；发表SCI、EI检索学术论文7篇，达到了项目计划任务的全部目标与考核要求，严格按照项目预算进行了项目研究经费的使用。