加锚结构面剪切特性及锚固岩体综合力学模型研究

发布时间：2018-08-11 12:58

【摘要】：目前,预应力锚固技术已经成为岩土工程中最常见的技术手段。从上世纪30年代起,伴随着几十年国内外大型岩土工程建设与相关技术发展,预应力锚固技术在高边坡加固中得到了广泛应用,其在结构设计、施工工艺、后期监测及加固机理研究等方面取得了若干重要成果。但由于岩体本身的复杂性和多样性,其力学性质是与其形成背景、地质构造作用历史、赋存环境以及工程设计等各种条件密切相关的,导致目前的锚固机理及分析方法还不够完善,对工程设计与评价方法指导性不足,成为制约该技术发展的一个重要瓶颈问题。在总结前人所取得的研究成果基础上,结合理论分析、物理模型试验及数值分析,开展加锚结构面剪切力学性能与锚固节理岩体综合力学模型建立方面的研究,一方面对于锚固技术发展、工程应用等方面有重要的意义,另外也为目前国家基础工程建设中的相关问题的解决提供重要的技术支持。结合前人相关研究成果,本文主要进行了以下几个方面的研究： (1)锚固结构面剪切力学特性分析。通过系统对以往岩体结构面的剪切力学行为的总结与归纳,定量地分析了预应力锚索在结构面剪切变形作用下的轴力增量、抗剪力以及预应力对结构面抗剪强度的贡献,并提出了锚固结构面的当量抗剪强度计算公式,并在此基础上推导了锚固结构面的等效抗剪强度参数计算公式。基于理论分析与模型试验,分析了锚索屈服强度、锚索弹性模量、岩块(砂浆)抗压强度、剪胀角等因素对锚固结构面抗剪强度特性的影响； (2)锚固结构面的室内模型试验研究。在锚固结构面剪切力学特性的分析成果基础上,对平直型结构面与起伏状结构面锚固前后的剪切破坏行为进行了室内模型试验。通过模型试验,总结了不同类型锚固结构面在不同应力条件下的剪切破坏模式；另外,通过模型试验对不同锚固作用下的结构面剪切强度进行了研究,验证了推导的锚固结构面当量抗剪强度计算公式的合理性；并结合模型试验,对预应力锚索的锚固角、锚索材料及结构面特性对锚索效用发挥进行了讨论； (3)锚固结构面剪切破坏过程的数值模拟。以室内模型试验为基础,建立平直型结构面与起伏状结构面的锚固力学模型,采用动力显示分析方法进行不同条件下的锚固结构面的细观力学行为进行研究,主要包括剪切过程中结构面应力分布、等效塑形应变分布、锚索受力及变形分析、结构面法向位移、抗剪强度特性等方面。结合室内模型试验成果,进一步总结归纳了预应力锚索对结构面的锚固作用规律； (4)结合预应力锚固机理分析,基于复合材料细观力学中Eshelby理论,将锚固节理岩体看作是单向增强的复合材料,提出了锚固节理岩体的综合力学模型,并推导了锚固节理岩体力学模型中各弹性常数的计算方法。并结合断裂力学等理论,对锚固节理岩体在沿锚索轴向受拉作用下的稳态开裂问题进行了探讨,提出了锚固节理岩体在轴向拉力作用下的开裂临界应力计算方法； (5)工程应用与分析。综合以上研究成果,以锦屏一级水电站左岸高边坡施工过程中的块体稳定分析为工程实例,提出了锚固结构面稳定分析时的等效抗剪强度分析方法,并通过工程实例应用可知,该方法较计算中仅考虑预应力作用时得到的安全系数要更加合理。
[Abstract]:Prestressed anchorage technology has become the most common technical means in geotechnical engineering. Since the 1930s, with the development of large-scale geotechnical engineering construction and related technology at home and abroad for decades, prestressed anchorage technology has been widely used in high slope reinforcement. It has been widely used in structural design, construction technology, post-monitoring and reinforcement machine. Some important achievements have been made in the study of rock mechanics. However, due to the complexity and diversity of rock mass itself, its mechanical properties are closely related to its formation background, history of geological tectonics, occurrence environment and engineering design, resulting in the imperfection of current anchorage mechanism and analysis methods, and the evaluation and design of engineering. Inadequate guidance has become an important bottleneck restricting the development of the technology.
On the basis of summing up the research results obtained by predecessors, combined with theoretical analysis, physical model test and numerical analysis, the research on shear mechanical properties of anchored structural plane and the establishment of comprehensive mechanical model of anchored jointed rock mass is carried out. On the one hand, it is of great significance to the development of anchorage technology and Engineering application, and on the other hand, it is also of great significance to China at present. It provides important technical support for solving the related problems in the construction of domestic infrastructure projects.
Combined with previous research results, this paper mainly carried out the following aspects:
(1) Analysis of shear mechanical properties of anchored structural planes. Based on systematic summary and induction of shear mechanical behavior of rock mass structural planes in the past, the axial force increment, shear resistance and contribution of prestress to shear strength of structural planes under shear deformation of structural planes are quantitatively analyzed, and the equivalent resistance of anchored structural planes is proposed. Based on theoretical analysis and model test, the influence of yield strength, elastic modulus of anchor cable, compressive strength of rock mass (mortar) and dilatancy angle on shear strength characteristics of anchored structural plane is analyzed.
(2) Laboratory model tests of anchored structural planes. Based on the analysis of shear mechanical properties of anchored structural planes, the shear failure behavior of flat and undulating structural planes before and after anchoring is studied by laboratory model tests. The shear behavior of different types of anchored structural planes under different stress conditions is summarized through model tests. In addition, the shear strength of structural plane under different anchorage is studied by model test, which verifies the rationality of the deduced formula for calculating the equivalent shear strength of anchorage structural plane. Theory;
(3) Numerical simulation of shear failure process of anchored structural plane. Based on laboratory model test, the anchorage mechanics model of flat and undulating structural plane is established. The micro-mechanical behavior of anchored structural plane under different conditions is studied by dynamic display analysis method, including stress distribution of structural plane in shear process. Based on the results of model tests in laboratory, the anchorage law of prestressed anchor cables to structural plane is summarized.
(4) Based on the Eshelby theory of composite micromechanics and the analysis of pre-stressed anchorage mechanism, a comprehensive mechanical model of anchored jointed rock mass is proposed, and the calculation method of elastic constants in the mechanical model of anchored jointed rock mass is deduced. The steady-state cracking problem of anchored jointed rock mass under axial tension along the anchor cable is discussed, and the calculation method of critical stress for cracking of anchored jointed rock mass under axial tension is proposed.
(5) Engineering application and analysis. Taking the block stability analysis during the construction of the left bank high slope of Jinping I Hydropower Station as an example, the equivalent shear strength analysis method for the stability analysis of the anchored structural plane is proposed. The application of the method to the engineering example shows that the method is more effective than that of the calculation only considering the prestressing force. The safety factor should be more reasonable.
【学位授予单位】：中国水利水电科学研究院
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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