NPR锚杆冲击拉伸动力学特性研究

发布时间：2018-06-05 06:03

本文选题：NPR锚杆 + 深部围岩大变形　；参考：《中国矿业大学(北京)》2016年博士论文

【摘要】：煤炭资源作为我国工业建设的主要能源,开采量和使用量愈来愈高,煤炭开采深度日益增加。目前我国主要煤矿开采深度已步入千米大关,巷道掘进和开采过程中遇到的深部围岩非线性破坏现象也越来越多。以冲击地压为代表,这些现象往往具有无征兆、过程短和破坏性强等特点,对人员和财产安全造成了严重威胁。因其发生原因复杂且难以观测,因此需要在灾害未发生之前便采取防治措施对巷道和工作面进行最大限度的保护。锚杆支护作为一种行之有效的支护方式,其具有成本低、人力低且使用简单等优点,已广泛应用于国内外煤矿和有色金属矿的支护过程中。锚杆是否有效取决于支护阻力和变形量为主要方面的力学参数,随着开采深度和安全要求的不断提高,传统锚杆因自身结构缺陷往往不能良好适用于深部围岩大变形破坏而导致支护失效。且基于传统材料研发的锚杆支护技术经过多年发展已出现瓶颈。因此需要开发具有超常性质的支护材料或结构,并建立新的关于复杂岩体的本构关系,形成一套专门适用于深部围岩大变形的锚杆支护体系理论显得迫在眉睫。何满潮院士首次在岩石力学领域中10-2~10 m的尺度上提出了负泊松比结构/材料的概念以及负泊松比的力学行为等科学问题,并基于恒阻大变形材料防冲控制理念于2011年设计并研发了具有负泊松比效应的恒阻大变形锚杆(即本文的NPR锚杆)。目前已对NPR锚杆已进行了众多室内外实验和现场工程应用,验证了其优越性的同时,对围岩稳定性控制技术及相应支护对策的探讨和实践也以取得良好效果。但与静态和准静态不同,结构和惯性效应将主要影响冲击荷载作用下材料的动态响应特性,即在动态冲击作用下,NPR锚杆能否呈现出由结构变形导致的负泊松比效应仍是未知。鉴于上述原因,本课题的研究将针对在动态冲击作用下NPR锚杆的动力学冲击拉伸特性这一关键问题,以NPR锚杆动力学特性为突破点,采用理论推导、工作原理分析、室内动力学实验和有限元分析相结合的方法,强调理论与实践的融合以及室内实验与数值模拟的统一。论文各部分研究内容和主要结论如下:通过系统阐述恒阻大变形材料防冲控制理念,即依靠恒阻大变形材料自身材料特性或结构特性来抵抗剩余外力荷载,避免材料破断失效的同时,吸收围岩的变形能量,使得支护体达到新的能量平衡。介绍了NPR锚杆和NPR岩体的相关概念及其两者的本构关系及支护原理,进而介绍了两者本构关系的解流变模型和解析模型,以及两者的理想弹塑性本构关系和复杂岩体定量化设计的可能性,并介绍了“无论岩体具有何种工程地质结构,在嵌入了NPR支护后,都将具有与NPR支护材料相似的本构关系”这一结论。为了分析和研究NPR锚杆的冲击动力学特性,何满潮院士基于传统SHPB实验系统改进研发了NPR锚杆冲击拉伸实验系统。本文介绍了SHPB实验系统的理论假设和注意问题,并对NPR锚杆冲击拉伸实验系统的系统组成、部件参数以及系统合理性进行详细的描述和分析。利用该实验系统,分别进行了多组单根和双根NPR锚杆实验,详细介绍了试件参数、实验准备和实验方法之后,对实验过程中出现的现象进行了科学分析。NPR锚杆冲击拉伸实验结果详细描述了NPR锚杆受冲过程中膨胀量、伸长量和冲击力等力学参数的变化情况。实验表明在经受动态冲击作用时,NPR锚杆恒阻装置受冲伸长的同时,其外螺纹凸处和凹处均膨胀变粗,且凹处变形量明显高于凸处,平均变形量达1.58mm。当杆体从恒阻套管冲出时杆体长度即为NPR锚杆最终拉伸量,本实验批次锚杆最终拉伸量可达450mm,进而计算得出本批次NPR锚杆等效负泊松比均值约为-0.15。不同气源压强冲击作用下,NPR锚杆承受的冲击力也正比增加,即吸收能量也随之增加,NPR锚杆每伸长单位长度耗能即锚杆抵抗变形能力也随着吸收能量的增加而增大。膨胀量、拉伸量和冲击力三者相互比较和分析,有效的验证了NPR锚杆在动态冲击时仍具有良好的适应性并表现出独特的负泊松比效应。对NPR锚杆冲击拉伸实验进行有限元分析,不仅可以验证实验结果的可靠性,也可以对NPR锚杆的改进进行可视化指导。介绍了常见有限元分析软件的优缺点并以此为依据采用CAD/CAE多软件集成有限元分析方法对实验系统进行数值模拟。按照模型建立、有限元前处理和求解计算的顺序介绍了NPR锚杆冲击拉伸实验有限元模拟流程,其中,详细描述了三维实体模型建立过程中所依据的简化建模准则和优化处理方案,详细说明了前处理过程中网格划分的方法和参数条件的选定。对NPR锚杆冲击拉伸实验系统进行子弹初速度为12m/s的动态冲击有限元分析,有限元膨胀量分析再现了恒阻套管螺纹凹处单元时刻与相邻单元挤压过程以及凹处和凸处单元的弹塑性变形过程;拉伸量分析表明锚杆轴向拉伸变形拥有与室内实验结果相类似的弹性回落现象;冲击力分析时进行了应力和冲击力的等效转换,得到的冲击力-时间曲线与室内实验结果相一致。对NPR锚杆冲击拉伸实验系统进行不同子弹初速度动态冲击的有限元分析,分析结果表明只有单次冲击时子弹速度满足使套管膨胀达到最大值时,NPR锚杆模型才能表现出明显的轴向拉伸。上述结论表明有限元分析结果与室内实验结果结果吻合度较高,进而验证了有限元分析和室内实验相结合的合理性和可行性。综上所述,通过NPR锚杆冲击拉伸实验验证了以动态冲击作用下NPR锚杆依然具有良好动力学特性并表现出独特的负泊松比特性的验证,通过有限元分析方法和室内实验相结合,可以合理高效的对不同要求下亟需的NPR锚杆进行相应的种类选定和参数改良。将NPR锚杆投入不同环境的生产和实践中去,对深部煤炭安全可持续开发利用有着不可忽视的积极作用,具有显著的社会效益和经济效益。
[Abstract]:As the main energy source of China's industrial construction, the coal resources are becoming more and more high, and the depth of coal mining is increasing. At present, the depth of the main coal mining in our country has entered into the kilometer. There are more and more nonlinear damage phenomena in the deep surrounding rock in the course of tunnel excavation and mining. The elephant often has the characteristics of no omen, short process and strong destructiveness and so on. It poses a serious threat to the safety of personnel and property. Because the cause is complicated and difficult to observe, it is necessary to take preventive measures to the maximum protection of the roadway and working face before the disaster occurs. Bolt support is a kind of effective supporting side. It has the advantages of low cost, low manpower and simple use. It has been widely used in the support process of coal mine and non-ferrous metal mine at home and abroad. Whether the bolt is effective depends on the mechanical parameters of the support resistance and the deformation amount as the main aspect. With the continuous improvement of the mining depth and safety requirements, the traditional bolt is often caused by its own structural defects. The support failure can not be well applied to the large deformation and failure of the deep surrounding rock, and the bolt supporting technology based on the traditional materials has been developed for many years. Therefore, it is necessary to develop the support material or structure with supernormal properties, and establish a new constitutive relation of complex rock mass, and form a set of special application for deep circumference. The theory of rock bolt supporting system with large rock deformation is imminent. The academician he Chao and Chao put forward the concept of negative Poisson ratio structure / material and the mechanical behavior of negative Poisson ratio on the scale of 10-2~10 m in the field of rock mechanics for the first time, and designed and developed in 2011 based on the concept of constant resistance and large deformation material control. With the negative Poisson ratio effect, the constant resistance large deformation bolt (the NPR anchor in this paper). At present, many indoor and outdoor experiments and field engineering applications have been carried out on the NPR bolt. The advantages are verified, and the discussion and practice of the stability control technology of the surrounding rock and the corresponding supporting measures are also achieved. The structure and inertia effect will mainly affect the dynamic response characteristics of the material under the impact load, that is, the negative Poisson ratio effect of the NPR bolt is still unknown under the dynamic impact. In view of the above reasons, the study of this subject will be aimed at the dynamic impact tensile of the NPR bolt under dynamic impact. The key problem of sex is the breakthrough point of the dynamic characteristics of NPR bolt. It adopts the method of theoretical deduction, working principle analysis, indoor dynamic experiment and finite element analysis. It emphasizes the integration of theory and practice, and the unification of indoor experiment and numerical simulation. The contents and main conclusions of the thesis are as follows: through the systematic exposition The anti impact control concept of the constant resistance large deformation material is to resist the residual force load by relying on the material properties or structural characteristics of the large deformation material, to avoid the failure of the material breaking and to absorb the deformation energy of the surrounding rock, so that the support can reach the new energy balance. The related concepts of the NPR bolt and the NPR rock mass are introduced and the constitutive relations of the two are introduced. The relationship and support principle are introduced, and then the rheological model and analytical model of the two constitutive relations are introduced, as well as the ideal elastoplastic constitutive relation of the two and the possibility of quantitative design for complex rock mass. "No matter what the engineering geological structure of the rock mass has, after embedded NPR support, it will have the similarity to the NPR support material." In order to analyze and study the dynamic characteristics of the impact dynamics of NPR bolt, academician He Manchao developed an experimental system of NPR bolt impact tensile test based on the traditional SHPB experimental system. This paper introduces the theoretical hypothesis and attention problems of the SHPB experimental system, and the system composition of the NPR bolt impact tensile test system and the component reference. The number and the rationality of the system are described and analyzed in detail. Using the experimental system, several groups of single and double NPR bolt experiments are carried out respectively. The parameters of the specimen, the experimental preparation and the experimental methods are described in detail. The results of the experiment in the experimental process are scientifically analyzed and the results of the.NPR bolt impact tensile test are described in detail NPR The change of the mechanical parameters, such as expansion, elongation and impact force in the process of bolting, shows that when the dynamic impact is subjected to dynamic impact, the constant resistance device of NPR bolt is expanded and expanded at the same time, and the deformation of the concave is obviously higher than that of the convex place, and the average deformation amount is up to 1.58mm. when the rod body is from the constant resistance casing. The length of the rod body is the ultimate tensile amount of the NPR bolt, and the final tensile amount of the bolt in this experiment can reach 450mm. Then it is calculated that the equivalent negative Poisson ratio of the batch NPR bolt is about -0.15. different gas pressure impact, and the impact force of the NPR bolt is also increased directly, that is, the absorption energy is also increased and the NPR bolt is elongated. The capacity of unit length energy dissipation, that is, the resistance to deformation of bolt, also increases with the increase of absorption energy. Expansion, tension and impact force are compared and analyzed. It is proved that the NPR bolt has good adaptability and unique negative Poisson's ratio effect in dynamic impact. The impact tensile test of NPR bolt is limited. The element analysis can not only verify the reliability of the experimental results, but also provide visual guidance for the improvement of the NPR bolt. The advantages and disadvantages of the common finite element analysis software are introduced. Based on the CAD/CAE multi software integrated finite element analysis method, the numerical simulation of the experimental system is carried out. The finite element simulation process of the NPR bolt impact tensile test is introduced in the order of calculation, in which the simplified modeling criteria and the optimal treatment scheme are described in detail, and the method of grid division and the selection of the parameters of the parameters are described in detail. The impact tensile test system of the NPR bolt is made. The dynamic impact finite element analysis of the initial velocity of 12m/s is carried out. The finite element expansion analysis reproduces the elastic-plastic deformation process of the extrusion process of the constant resistance casing thread and the adjacent unit and the concave and convex units, and the tensile strength analysis shows that the axial tensile deformation of the bolt has the similar elasticity to the laboratory experimental results. The equivalent conversion of stress and impact force is carried out in the analysis of the impact force. The impact force time curve is in accordance with the laboratory results. The finite element analysis of the dynamic impact of the initial velocity of different bullets on the NPR bolt impact tensile test system is analyzed. The analysis results show that the bullet velocity satisfies the casing expansion only when the single impact is impacted. When the expansion reaches the maximum value, the NPR anchor model can show obvious axial tension. The above conclusion shows that the results of finite element analysis are in good agreement with the experimental results, and the rationality and feasibility of combining the finite element analysis with the laboratory experiment are verified. In summary, the dynamic test of the NPR bolt is proved to be dynamic by the impact tensile test. Under impact, the NPR bolt still has good dynamic characteristics and shows unique negative Poisson ratio characteristics. Through the combination of the finite element analysis method and the laboratory experiment, the corresponding selection and parameter improvement of the NPR bolt which are needed under different requirements can be reasonably and efficiently. The production of NPR bolt in different environment can be put into production. And in practice, it plays an important role in the sustainable development and utilization of deep coal. It has significant social and economic benefits.
【学位授予单位】：中国矿业大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TD353.6

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