黏土层中拉力型预应力锚杆（索）荷载传递试验研究

发布时间：2018-02-13 01:42

本文关键词： 黏土层预应力锚杆(索) 剪应力试验粘结强度　出处：《昆明理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：预应力锚杆(索)作为一种重要的岩土锚固技术,在工程领域有着广泛的应用。目前在关于预应力锚杆(索)的各种设计规范中,均按照平均粘结强度进行锚杆长度的设计,其合理性和安全性值得商榷。探究预应力锚杆(索)内锚固段的荷载传递性状以及锚杆在服役阶段的工作性能等,具有重要的工程应用价值和较高的学术价值。本文考虑土层预应力锚杆(索)在受荷过程中,土体和固结体界面的部分脱粘滑移特性,将锚杆锚固段分为滑移段和弹性段。滑移段剪应力以滑动摩擦力的形式体现,呈线性分布。对弹性段的分析,结合弹性半无限空间内一点受集中力的Mindlin位移解,获得了弹性段剪应力分布的微分方程,剪应力表现为单峰曲线形式。通过室内试验,对多束钢绞线整体受荷时的工程等效弹性模量进行测试分析,为工程锚索的张拉计算提供了真实可靠的依据。并对电阻应变片偏轴测量钢绞线应变时的修正系数进行测试,为预应力锚索现场试验提供可靠参数。依托在施桩锚结构基坑工程,针对特定黏土层中预应力锚杆(索),在张拉受荷过程中,锚固段杆体(钢绞线)沿锚固段的轴向应变进行测试,经转换得到锚杆锚固段剪应力沿杆长的分布变化规律,实测数据和理论分析具有较好的吻合性,验证了理论分析的合理性。结合理论分析和试验结果,从实测数据出发,对现行规范中关于预应力锚杆(索)的设计取值进行一定的系数修正,使之更真实的反映土层锚杆的受荷工作状态。提出锚固段发挥系数ε的概念,找寻不同锚杆在不同工作状态下,锚固段发挥系数的规律和取值。同时结合相关规范,对锚杆在验收试验中的验收荷载,验收合格标准和验收荷载下的实际抗拔安全系数,提出了新的思考。预应力锚杆(索)在岩土锚固中有着举足轻重的作用,本文所获得的研究成果对锚杆的设计理论和施工、试验提供了一定的参考。
[Abstract]:As an important rock and soil anchoring technology, prestressed anchor rod (cable) is widely used in engineering field. At present, the length of anchor rod is designed according to the average bond strength in various design specifications of prestressed anchor rod (cable). It is worth discussing its rationality and safety. It has important engineering application value and high academic value to explore the load transfer behavior of anchoring section in prestressed anchor rod (cable) and the working performance of anchor rod in service stage. In this paper, the partial debonding and slip characteristics of the interface between soil mass and consolidation body are considered during the loading process of the prestressed anchor (cable) in soil layer. The anchoring section of the anchor is divided into sliding section and elastic section. The shear stress of the slip section is reflected in the form of sliding friction force. The differential equation of shear stress distribution of elastic segment is obtained by combining the Mindlin displacement solution of a point in elastic semi-infinite space with a concentrated force. The shear stress is expressed as a single-peak curve form. Through laboratory tests, the equivalent elastic modulus of multi-beam steel strands subjected to integral loading is measured and analyzed. It provides a real and reliable basis for the calculation of the tension of the engineering anchor cable, and tests the correction coefficient of the deflection axis of the resistance strain gauge for measuring the strain of the steel strand, which provides reliable parameters for the field test of the prestressed anchor cable. Based on the foundation pit engineering of pile and anchor structure, the axial strain of anchor bar (steel strand) along the anchoring section is measured in the course of tension and loading of prestressed anchor rod (cable) in a specific clay layer. The distribution of shear stress along the length of bolt is obtained by conversion. The measured data are in good agreement with the theoretical analysis, which verifies the rationality of the theoretical analysis. Based on the theoretical analysis and test results, the design value of prestressed anchor rod (cable) in the current code is modified from the measured data. The concept of play coefficient 蔚 of anchoring section is put forward to find out the law and value of the performance coefficient of anchor section under different working conditions. A new consideration is put forward on the acceptance load of anchor rod in the acceptance test, the acceptance standard and the actual uplift safety factor under the acceptance load. The prestressed anchor rod (cable) plays an important role in the rock and soil anchoring. The research results obtained in this paper provide a certain reference for the design theory and construction of the anchor rod.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU476

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