预应力锚索在黄土地层的锚固效果研究

发布时间：2018-07-11 12:33

本文选题：预应力锚索 + 拉拔试验　；参考：《西安科技大学》2017年硕士论文

【摘要】：岩土锚固体系是大型岩土工程的重要组成部分,岩土锚固效果决定着岩土锚固体系的安全性和长久性,岩土锚固由于其特有的优势而迅速发展并广泛应用起来。预应力锚索内锚固段是锚固体系的主要组成部分,是锚固体系的主要受力和传力结构,锚固段的受力状态对锚固体系的锚固效果有重要影响,因此对预应力锚索的锚固效果及荷载传递规律的研究具有重要的理论意义和工程意义。本文通过现场试验、理论分析及数值模拟等方法,对预应力锚索的荷载传递及锚固效果进行了深入的研究,主要开展了以下方面的研究:1、通过调查、资料收集等手段,将影响锚索锚固效果的内在因素作为研究对象,制定预应力锚索现场试验方案;通过改变锚索锚固段长度和注浆体配合比等因素,在黄土地层中对预应力锚索进行了现场试验,得到了锚索的P-S曲线;分析了对各因素下锚索的锚固效果及破坏模式;总结了现有的锚索拉拔P-S曲线模型,同时分析了现场试验的P-S曲线在各级荷载作用下锚索的弹性位移和弹塑性位移。2、基于B.Benmokrane建立的剪切滑移本构模型,推导了在拉拔荷载作用下锚固段在不同变形阶段轴力、锚固层界面剪力及变形分布规律,并给出了锚固段分别在弹性变形阶段和弹塑性变形阶段的极限承载力的计算公式;结合理论分析得到了锚固段与岩土体界面分别在弹性变形阶段的抗剪强度参数1τ、1K和弹塑性变形阶段的抗剪强度参数2τ、2K的确定方法,并结合现场试验的P-S曲线,给出了现场试验的抗剪强度参数,并结合算例对锚索的荷载传递规律进行了分析。3、锚固段横向方向的受力,基于Pasternak弹性地基梁模型,推导出在横向荷载作用下锚固段的挠度、弯矩、剪力、转角和土体反力的分布规律,并给出了锚固段在横向荷载作用下岩土体松动区范围及锚固段破坏时的最大剪切位移的计算方法;以黄土地层为算例,分析了锚固段在横向荷载下受力和变形规律,并对其影响参数进行了分析。4、结合现场试验的抗剪刚度参数,给出了剪切滑移uτ-本构关系,并结合剪切滑移本构方程对ANSYS中非线性弹簧单元建立了F-D本构关系,对锚索锚固段的粘结滑移关系进行了数值模拟分析,结合理论分析和现场试验对比分析,说明了ANSYS有限元软件对锚索锚固段的粘结滑移性能的数值模拟可行性较好,对预应力锚索荷载传递规律的认识及锚索锚固效果的研究有一定的指导意义。
[Abstract]:Rock and soil anchoring system is an important part of large geotechnical engineering. The effect of rock and soil anchoring determines the safety and longevity of rock and soil anchoring system. Because of its unique advantages, geotechnical anchoring develops rapidly and is widely used. The internal anchoring section of prestressed Anchorage cable is the main component of the Anchorage system, which is the main force and transmission structure of the Anchorage system. The stress state of the Anchorage section has an important influence on the anchoring effect of the Anchorage system. Therefore, it is of great theoretical and engineering significance to study the anchoring effect and load transfer law of prestressed Anchorage cable. In this paper, through field test, theoretical analysis and numerical simulation, the load transfer and anchoring effect of prestressed Anchorage cable are deeply studied. The following aspects are mainly studied: 1, through investigation, data collection, etc. Taking the internal factors which affect the anchoring effect of anchor cable as the research object, the field test scheme of prestressed anchor cable is established, and the field test of prestressed anchor cable is carried out in the loess layer by changing the length of anchoring section and the proportion of grouting body, and other factors, such as changing the length of anchoring section of anchor cable and the proportion of grouting body, etc. The P-S curve of anchor cable is obtained, the anchoring effect and failure mode of anchor cable under various factors are analyzed, and the existing P-S curve model of cable drawing is summarized. At the same time, the elastic displacement and elastic-plastic displacement of the anchor cable under various loads are analyzed. Based on the shear slip constitutive model established by B. Benmokrane, the axial forces of the anchoring section at different deformation stages under the pull-out load are derived. The distribution of shear force and deformation at the interface of Anchorage layer is studied. The calculation formulas of ultimate bearing capacity of Anchorage section in elastic deformation stage and elastic-plastic deformation stage are given. Based on the theoretical analysis, the determination method of shear strength parameter 1 蟿 ~ 1K at elastic deformation stage and shear strength parameter 2 蟿 ~ (2K) at elastic deformation stage at the interface of Anchorage section and rock and soil is obtained, and the P-S curve of field test is combined. The shear strength parameters of field test are given, and the load transfer law of Anchorage cable is analyzed. 3. Based on Pasternak elastic foundation beam model, the deflection of anchoring section under transverse load is deduced. The distribution law of bending moment, shear force, rotation angle and soil reaction force is given, and the calculation method of maximum shear displacement of loose zone of rock and soil under transverse load and failure of anchoring section is given. The law of stress and deformation of Anchorage section under transverse load is analyzed, and the influence parameters of Anchorage section are analyzed. The shear slip u 蟿 -constitutive relation is given according to the shear stiffness parameters of field test. Based on the shear slip constitutive equation, the F-D constitutive relation of nonlinear spring element in ANSYS is established, and the bond-slip relationship of anchor cable is numerically simulated and compared with the theoretical analysis and field test. It is shown that the ANSYS finite element software is feasible for numerical simulation of the bond-slip behavior of the anchoring section of the anchor cable, and has certain guiding significance for the understanding of the load transfer law of the prestressed anchor cable and the study of the anchoring effect of the anchor cable.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU444;TU476

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