扩底锚杆基础拉拔作用下的力学性能及破坏模式分析

发布时间：2018-03-15 08:20

本文选题：扩底锚杆　切入点：Q-S曲线　出处：《沈阳建筑大学》2014年硕士论文　论文类型：学位论文

【摘要】：风力发电是当前可再生能源中仅次于水力发电的技术最成熟、最具规模化开发的发电方式之一。近年来,国内许多风电场工程已相继建成发电或正在建设,但涉及风电机组安全的风电机组基础设计一直没有专门的设计规范,设计中一般借鉴建筑、电力等行业的相关规范。借鉴其他行业标准,造成风电机组基础设计偏于保守。风力发电机主要受到风的横向水平作用,在水平作用下使基础稳定不倾覆,就十分重要了。传统的风机基础为重力式扩大基础,但它不能很好发挥岩体的力学性能,由此改进一种新型的风机基础：岩石锚杆基础。扩底锚杆是一种特殊锚杆,是在原有等截面锚杆的基础上,在锚杆底部通过专用设备形成“扩大头”,因而称之为“扩底锚杆”。扩底锚杆的扩大头把一部分桩身摩阻力转化为端阻力,从而提高了抗拔承载力。由于它具有抗拔性能好的优点,近年来,在工程中,尤其是输电线路和地下结构中得到了比较广泛的应用。目前,对扩底锚杆的理论研究还未跟上应用水平,扩底锚杆的承载能力只有通过现场荷载试验才能确定。但是试验不仅花费时间长、耗资巨大、代表性差,而且很难测出完整的Q-S曲线。因此有必要对扩底锚杆的承载性状进行探讨,提出更为合理的确定扩底锚杆承载力的数值模拟方法。本文选用了ANSYS数值计算软件建立了扩底锚杆-岩土相互作用模型,对扩底锚杆的受力性状进行了深入细致的探讨和分析。研究的主要内容有：(1)采用有限元方法,利用通用有限元软件ANSYS建立轴对称分析模型,锚杆-岩土之间设置接触单元模拟锚杆-岩土的分离与滑动,考虑土体初始应力与大变形,模拟锚杆在上拔荷载作用下的工作机理。(2)扩底锚杆抗拔机理、荷载传递规律以及岩土体变形破坏机理进行了分析,得到了其极限承载力并与目前世界上一些国家基础设计规范中仍普遍采用的“土重法”计算理论进行比较。并在此基础上探讨了影响扩底锚杆抗拔极限承载力的主要因素以及不同土层的情况下,扩底锚杆的抗拔机理。(3)采用三维有限元方法,锚杆-岩土间设置接触,研究多根扩底锚杆在上拔荷载作用下的承载力。讨论了多根扩底锚杆共同作用下的承载机理以及群锚作用对竖向受荷扩底锚杆承载力的影响。最后对本文工作进行了总结,归纳出了本文的主要结论,并给出了今后的研究方向。
[Abstract]:Wind power generation is one of the most mature and large-scale power generation methods in renewable energy. In recent years, many wind farm projects in China have been built to generate electricity or are under construction. However, there has been no special design specification for wind turbine foundation design involving wind turbine safety. The design generally draws lessons from the relevant codes of construction, electricity and other industries, and draws lessons from other industry standards. The wind turbine foundation design is conservative. The wind turbine is mainly affected by the horizontal wind. It is very important to make the foundation stable and not overturned under the horizontal action. The traditional fan foundation is gravity expansion foundation. But it can not give full play to the mechanical properties of rock mass, so it can improve a new type of fan foundation: rock anchor base, which is a special kind of anchor, which is based on the original anchor with equal section. The "enlarged head" is formed by special equipment at the bottom of the anchor rod, so it is called "enlarged anchor rod". The enlarged head of the expanded anchor rod transforms part of the pile friction into end resistance. It has been widely used in engineering in recent years, especially in transmission lines and underground structures. The theoretical research on the belled anchor rod has not kept up with the application level, and the bearing capacity of the belled anchor rod can only be determined by the field load test, but the test takes not only a long time, a huge cost, but also a poor representativeness. And it is difficult to measure the complete Q-S curve. Therefore, it is necessary to discuss the bearing behavior of the belled anchor. A more reasonable numerical simulation method for determining the bearing capacity of reamed anchor rod is put forward. In this paper, the ANSYS numerical calculation software is used to establish the model of the rock-soil interaction between the belled anchor rod and the rock-soil. The mechanical behavior of belled anchor rod is discussed and analyzed in detail. The main content of the study is: using finite element method, using the general finite element software ANSYS to establish the axisymmetric analysis model. The contact element between anchor and rock soil is set up to simulate the separation and sliding of anchor rod and rock soil. Considering the initial stress and large deformation of soil, the working mechanism of anchor rod under uplift load is simulated. The law of load transfer and the mechanism of deformation and failure of rock and soil are analyzed. The ultimate bearing capacity is obtained and compared with the calculation theory of "soil weight method", which is still widely used in the foundation design codes of some countries in the world at present. On this basis, the influence of the ultimate bearing capacity of the reamed anchor rod on the pull-out ultimate bearing capacity is discussed. In the case of major factors and different soil layers, Three dimensional finite element method is used to establish contact between anchor rod and rock soil. The bearing capacity of multiple reamed anchor rods under uplift load is studied. The bearing mechanism and the effect of group anchors on the bearing capacity of bolting bolts under vertical loading are discussed. Finally, the work of this paper is summarized. The main conclusions of this paper are summarized and the future research directions are given.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU473.1

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