【作者】 白金超；

【导师】 欧进萍；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2008， 硕士

【摘要】 本文从解决岩土锚固安全问题的角度出发,针对锚固耐久性及其安全监测需要,结合FRP材料的优良特性和光纤光栅传感器的感知性能,研制开发出了FBG-FRP智能锚杆,通过理论分析和有限元模拟研究了FRP锚杆的工作机理,并根据岩土锚固的目的确定了锚固系统的监测内容及方法,构建了岩土锚固的智能监测系统,主要研究内容如下:首先,介绍了FRP材料的构成及其特点,阐述了FBG的传感原理及其参数选取原则,在此基础上,构思并开发出了FBG-FRP智能锚杆,该锚杆能充分发挥FRP材料的优点来满足岩土锚固的需求,同时具有耐腐蚀、易清除和自监测等优点。其次,分析了在轴向荷载作用下FRP锚杆锚固段上的界面粘结力分布特征,并基于Mindlin问题的位移解将其与钢锚杆做了对比计算;根据简化的粘结-滑移关系,从围岩与锚杆相互作用的角度,推导了FRP锚杆轴力和界面剪切力的计算公式;研究了FRP锚杆的存在对节理面抗剪能力的影响,并分析了在发生拉剪大变形时,FRP锚杆在节理面上的变形角及内力的计算方法,还结合Tsai-Hill破坏判据提出了FRP锚杆的拉剪破坏准则。接着,针对采用ANSYS自带库仑摩擦模型模拟锚杆-砂浆滑移时存在的缺陷,提出了引入“生死”单元的方法,成功地建立了与试验结果吻合得较好的FRP锚杆拉拔试验有限元模型;根据数值模拟结果,分析了FRP锚杆与砂浆界面的剪切力随拉拔荷载增大时的演化过程,以及锚固系统的内力和位移的分布特征,并讨论了锚固长度对锚杆承载力的影响。最后,分析了使用传统拉拔试验方法检测锚固质量时的不足;基于岩土锚固的目的,提出了锚固效果的评价指标及其监测内容;讨论了钻孔过程、锚杆内力、锚固段长度及密实度、围岩压力和位移等方面的监测方法,并据此构建了岩土锚固的智能监测系统,还提出了锚固系统的动态设计与全寿命维护的思路。更多还原

【Abstract】 To solve the security problem of ground anchorage system, this paper aims at the need of durability and safety monitoring of ground anchorage. Considering the excellent characteristics of FRP material and FBG’s sensing properties, a new kind of FBG-FRP intelligent anchor bolts has been developed. The working mechanism of FRP anchor bolts has been studied by theoretical analysis and finite element simulation. The contents and approaches for monitoring of the anchorage systems have been determined according to the objective of ground anchorage, and the intelligent monitoring systems of ground anchorage have been set up. The main contents include:Firstly, the composition and characteristics of FRP material have been introduced, FBG’s sensing properties and principles of parameters selection have also been described, and then, the intelligent FBG-FRP anchor bolts have been conceived and developed. The FBG-FRP anchor bolts can fully exert the advantages of FRP material to meet the needs of ground anchorage, and they also have many properties such as corrosion resistant, easy to be eliminated, self-monitoring, et al.Secondly, lateral resistance distribution of FRP bolt’s anchoring section has been studied, and it also has been compared to the steel anchor bolt based on the Mindlin’s solution of displacement in elastic theory. According to a simplified bond-slip relationship of FRP bar and mortar, the calculation formulas of axial force and interfacial shear stress of FRP anchor bolt have been derived from the interaction of the surrounding rock and anchor bolt. The effect of FRP anchor bolts on the resisting shear ability of joint surface has been studied. The calculation methods of FRP bolts’deformation angles and internal force under the shearing-tensile load are put forward, and the failure criterion for FRP anchor bolts with axial shear combined force using the Tsai-Hill criterion is presented as well.Thirdly, to avoid the defect that occurred when using the ANSYS’Coulomb friction model to simulate the sliding between bolt and mortar, a method of introducing birth-death element has been proposed, and a FEM model of FRP anchor bolt’s pull-out test has been established, the analysis results by which can accurately fit the field data. The evolutionary process of shear distribution on the anchorage interface with the increase of load has been analyzed by FEM, and the distribution features of the anchorage system’s internal force and displacement have also been studied.Fourthly, the deficiencies of the pull-out test are summarized when it is used to detect the anchoring quality as a traditional method. Based on the purpose of ground anchorage, the evaluation indexes of the anchoring effects have been determined. According to those indexes, the monitoring contents should include drilling processes, the internal force of the bolts, the length of anchoring sections, the mortar compactness, the pressure and displacement of the surrounding rock. And the monitoring methods of the contents have been discussed, based on that, the intelligent monitoring system of ground anchorage is set up, the thought of dynamic design and security maintenance of anchorage system is also put forward.更多还原