块状岩体锚固力学特性研究

发布时间：2018-01-06 16:44

本文关键词：块状岩体锚固力学特性研究　出处：《中国矿业大学》2016年硕士论文　论文类型：学位论文

【摘要】：块状岩体作为一种常见工程岩体,其内部的各种节理、层理等弱面对岩体结构整体稳定性及工程安全具有重要影响。锚杆支护作为现在围岩稳定控制的主要手段,深入研究各因素下加锚块状岩体强度特性及变形特征,分析内部应力分布及锚杆作用机理,对实际工程中锚杆支护设计具有重要的意义。本文以煤矿巷道顶板块状岩体为研究对象,利用物理模型试验及数值模拟,对不同块体特征及不同锚固条件下块状岩体锚固特性进行研究,分析各因素对锚固体模型强度特性、变形特征、锚杆受力及内部应力分布的影响,并在此基础上对块状岩体锚固机理进行了分析。主要研究成果如下:(1)基于巷道围岩锚固体单元简化力学模型,设计了类岩石锚固体试验模拟系统,以实现加锚块状岩体压缩试验过程中力学边界条件模拟与控制;基于相似准则,主要考虑岩体、结构面及锚杆材料的相似性,进行基本力学性质测试,并制备块状岩体试样。(2)通过对不同块体特征及锚固参数下各模型进行试验,结果表明加锚之后,模型峰值应力及弹性模量明显增大;随着块体大小、锚固长度、锚固密度及锚杆预紧力的增大,模型峰值应力及弹性模量也基本呈增大趋势;通过因素敏感度分析发现基准状态时各因素对锚固体强度的影响主次顺序为:块体大小锚固方式锚杆密度锚杆预紧力。(3)通过锚杆轴力监测发现锚杆轴力随时间主要经历了缓慢增长期、快速增长期、稳定期或降低期、失效期;模型破坏形式主要有剪切滑移破坏、X型剪切破坏和剪切劈裂混合破坏,揭示了加锚块状岩体中锚杆的主要作用是提高结构面的抗剪强度。(4)在物理模拟的基础上,利用非连续体离散元数值反演方法建立与物理模拟试验相吻合的数值模型;通过研究发现,节理及层理倾角对模型峰值强度影响明显,节理1及层理倾角对弹性模量也有明显影响,而节理2对模型弹性模量影响较小。(5)锚杆对锚固体模型位移场及应力场有明显影响,由于锚杆作用而在模型中形成锥形压缩区,且相邻锚杆作用形成的压缩区相互叠加而形成锚固带;块体沿模型内部弱面有明显的滑移,且在弱面位置发生明显的应力变化。块状岩体锚固机理是通过锚杆的挤压作用提高结构面强度特性,改善岩体受力特性,进而提高锚固体承载特性。
[Abstract]:As a common engineering rock mass, massive rock mass has various joints in its interior. The whole stability and engineering safety of rock mass structure with weak face such as bedding have important influence. Anchor support is the main means of stability control of surrounding rock. The strength and deformation characteristics of bolted rock mass under various factors are studied deeply, and the internal stress distribution and anchoring mechanism are analyzed. This paper takes the roof block rock mass of coal mine roadway as the research object, using physical model test and numerical simulation. This paper studies the anchoring characteristics of block rock mass under different block characteristics and different anchoring conditions, and analyzes the influence of various factors on the strength characteristics, deformation characteristics, bolt force and internal stress distribution of anchor body model. The main research results are as follows: (1) based on the simplified mechanical model of roadway surrounding rock Anchorage unit, a rock Anchorage test simulation system is designed. In order to realize the simulation and control of mechanical boundary conditions in the compression test of bolted rock mass; Based on the similarity criterion, the similarity of rock mass, structural plane and anchor material is considered, and the basic mechanical properties are tested. The results show that the peak stress and elastic modulus of the model increase obviously after anchoring. With the increase of block size, anchoring length, anchoring density and anchor pre-tension force, the peak stress and elastic modulus of the model also show an increasing trend. Through factor sensitivity analysis, it is found that the influence of various factors on the strength of anchor body is in the order of: block size anchoring mode anchor bolt density anchor pre-tension force. Through the monitoring of the axial force of the anchor rod, it is found that the axial force of the bolt has mainly experienced a slow growth period with time. Rapid growth period, stable period or decrease period, failure period; The failure modes of the model are mainly shear slip failure X type shear failure and shear split mixed failure. It is revealed that the main function of anchor rod in bolted block rock mass is to improve the shear strength of structural plane. (4) on the basis of physical simulation. The discrete element numerical inversion method of discontinuities is used to establish a numerical model which is consistent with the physical simulation test. It is found that joint and bedding dip angle have obvious influence on the peak strength of the model, and joint 1 and bedding dip angle also have obvious influence on elastic modulus. Joint 2 has little effect on the elastic modulus of the model.) the anchor rod has obvious influence on the displacement field and stress field of the Anchorage model, and the conical compression zone is formed in the model because of the effect of the anchor rod. And the compression zone formed by the action of adjacent bolt superposes with each other to form the anchoring zone; The block has obvious slip along the weak plane of the model and obvious stress changes in the weak plane. The anchoring mechanism of block rock mass is to improve the strength characteristics of the structural plane and the stress characteristics of the rock mass through the extrusion action of the anchor rod. Furthermore, the bearing characteristics of anchors are improved.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD353

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