疲劳荷载与腐蚀耦合作用下岩土预应力锚固结构长期耐久性研究

发布时间：2018-10-07 18:55

【摘要】：岩土锚固技术是用来加固处理岩土体的一种常用且高效的方法。采用预应力锚固技术对岩土工程中的结构物进行加固,能达到控制变形、保持系统稳定的良好效果。它具有以下优点:效果好、施工简便、安全可靠、造价低,现已被广泛应用于边坡、基坑、隧道、地下洞室、矿山等工程中。但是预应力锚固结构在工作期间要一直承受拉应力作用,并且结构周围环境复杂,存在大量的侵蚀性介质和杂散电流,容易使钢筋腐蚀。所以预应力锚固结构会因荷载和腐蚀的影响而逐渐老化破坏,从而导致其耐久性逐渐降低,并最终失效,因此,非常有必要对预应力锚固结构的耐久性开展研究。本文通过室内试验、理论分析及数值模拟等手段,对疲劳荷载与腐蚀耦合作用下岩土预应力锚固结构的耐久性进行了研究,分析了疲劳荷载和腐蚀两种因素对钢筋性能的影响,并通过数值模拟研究了内锚固段破坏及变化规律。具体研究内容如下:(1)对钢筋进行一定时间的疲劳及腐蚀试验,将钢筋分组编号,分别施加不同的疲劳拉伸次数,放置于不同的酸碱环境中,由此得到疲劳荷载及腐蚀对钢筋性能的影响。选取典型的钢筋试件,分别进行拉裂和电镜扫描,从宏观和微观角度观察钢筋断口,分析疲劳荷载与腐蚀耦合作用下钢筋的力学性能变化和断裂特征。(2)采用PFC2D程序分别建立了预应力锚固结构承受疲劳荷载与腐蚀耦合作用及仅承受疲劳荷载作用的数值模型。对比分析了两种条件下锚杆-注浆体界面剪应力、钢筋轴向应力、位移场的变化特征,得到了疲劳荷载与腐蚀耦合作用下内锚固段锚杆-注浆体界面粘结劣化的细观规律。(3)采用PFC2D程序建立预应力锚固结构在疲劳荷载与腐蚀耦合作用下的数值模型,分别研究注浆体强度、围岩体强度、锚固长度这三个因素对预应力锚固结构耐久性的影响,并依此提出增强预应力锚固结构长期耐久性的针对性措施。
[Abstract]:Rock-soil Anchorage technology is a common and efficient method to reinforce and treat rock and soil. The prestressed Anchorage technique is used to reinforce the structures in geotechnical engineering, which can control the deformation and maintain the stability of the system. It has the following advantages: good effect, simple construction, safe and reliable, low cost, and has been widely used in slope, foundation pit, tunnel, underground cavern, mine and so on. However, the prestressed Anchorage structure has been subjected to tensile stress during the working period, and the surrounding environment of the structure is complex, there are a large number of erosive media and stray current, so it is easy to corrode the steel bar. Therefore, the prestressed Anchorage structure will be gradually aged and destroyed because of the influence of load and corrosion, which will lead to the gradual decrease of its durability and its ultimate failure. Therefore, it is very necessary to study the durability of prestressed Anchorage structure. By means of laboratory test, theoretical analysis and numerical simulation, this paper studies the durability of geotechnical prestressed Anchorage structure under the coupling of fatigue load and corrosion, and analyzes the influence of fatigue load and corrosion on the performance of steel bar. The failure and variation of the inner Anchorage section are studied by numerical simulation. The specific research contents are as follows: (1) carrying out fatigue and corrosion tests on steel bars for a certain period of time, numbering the steel bars into groups, applying different fatigue tensile times respectively, and placing them in different acid-base environments. The influence of fatigue load and corrosion on the performance of steel bar is obtained. The typical steel bar specimen was selected and scanned by tensile crack and electron microscope respectively. The fracture surface of steel bar was observed from macroscopic and microscopic angles. The mechanical properties and fracture characteristics of steel bars under the coupling of fatigue load and corrosion are analyzed. (2) the numerical models of prestressed Anchorage structure subjected to the coupling of fatigue load and corrosion and only fatigue load are established by PFC2D program. The variation characteristics of shear stress, axial stress and displacement field of the bolt-grouting body interface under two kinds of conditions are compared and analyzed. The mesoscopic law of bond deterioration at the interface between anchor rod and grouting body under the coupling of fatigue load and corrosion is obtained. (3) the numerical model of prestressed Anchorage structure under the coupling of fatigue load and corrosion is established by using PFC2D program. The effects of grouting strength, surrounding rock strength and anchoring length on the durability of prestressed Anchorage structure are studied, and corresponding measures to enhance the long-term durability of prestressed Anchorage structure are put forward.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU476

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