散粒体斜坡稳定性分析方法实验研究

发布时间：2018-04-25 07:11

本文选题：散粒体斜坡 + 单颗粒　；参考：《成都理工大学》2015年硕士论文

【摘要】：散粒体斜坡又称溜砂坡,在我国西南和西北部的一些地区区域性的分布,通常由碎石、砾石和砂组成,呈散体结构,几乎没有细粒和其他胶结物连接,呈现出“一盘散沙”的状态。散粒体斜坡通常对外界扰动非常的敏感,因此频繁活动,对沿线的线性交通的安全运行造成危害,同时由于散粒体变形破坏有明显的突发性,因此对人身和财产安全造成很大的威胁。散粒体斜坡变形破坏的研究起步较晚,前人的研究主要集中在散粒体堆积体的非线性动力学方面,通过沙堆试验或者单面坡试验等物理试验模拟,认为散粒体边坡是一个典型的多元广延空间自由度的耗散动力学系统,符合自组织临界性原理,当坡面上一点失稳就可能会波及周围其他临近区域,导致坡面大面积的散粒体物质失稳,并且散粒体的自组织临界性受到规模和级配的影响。由于这种自组织临界性,散粒体斜坡在临界状态下受到扰动时出现的破坏形式和规模不可预知。本文认为散粒体斜坡既有表面单个颗粒或者多个颗粒的运动,也有大规模的整体失稳,在广泛收集国内外有关散粒体文献资料和大量现场第一手资料的基础上,采用理论推导和物理模拟试验的手段,从地质灾害学的角度对其进行探索研究。主要内容包括:(1)通过野外调查并取样筛分,分析散粒体斜坡的分布特征、物质组成、形成条件和影响因素。(2)分析散粒体颗粒之间的接触作用,通过直剪实验的方法研究颗粒的抗剪强度特征,分析说明颗粒粒径以及级配对抗剪强度的影响。(3)划分了散粒体斜坡的活动阶段,阐明散粒体斜坡表层颗粒的运动破坏形式。分析了表层单颗粒起动的力学判据,通过实验的方法验证了单颗粒起动判据的实用性,与实验值非常吻合,即表层单个规则颗粒起动与颗粒本身的重量无关,只要几何特征满足颗粒即可起动;并且散粒体单颗粒的启动判据能很好的解释散粒体斜坡的分选性。研究表明颗粒形状对颗粒起动条件有较大的影响。(4)通过物理模拟整体变形破坏机制,并提出三种散粒体边坡变形破坏模式即表面颗粒滑流,蠕滑剪出破坏和溃散破坏。(5)对散粒体斜坡的稳定性评价进行进一步研究。在散粒体斜坡的稳定性评价方法方面,结合物理模拟实验,针对破坏模式,有针对性提出稳定性判别方法。针对表面颗粒滑流破坏模式提出关键颗粒的判别方法;针对蠕滑整体剪出破坏模式,提出采用传统的毕肖普条分法。
[Abstract]:A regional distribution in some parts of the southwest and northwest of China, usually composed of gravel, gravel, and sand, with a granular structure and almost no fine grain and other cementation. It presents a state of "scattered sand". Granular slopes are usually very sensitive to external disturbances, so frequent activities are harmful to the safe operation of linear traffic along the route. At the same time, there are obvious sudden damage due to the deformation and failure of granular bodies. Therefore, it poses a great threat to the security of person and property. The research on the deformation and failure of granular slope started relatively late. The previous studies mainly focused on the nonlinear dynamics of granular accumulations, and simulated by physical tests such as sand pile test or single slope test. It is considered that the granular slope is a typical dissipative dynamic system with multiple and extensive spatial degrees of freedom, which accords with the principle of self-organizing criticality. When a single point of instability on the slope surface is unstable, it may spread to other adjacent areas around the slope. It leads to the instability of large area of granular matter on the slope and the influence of size and gradation on the self-organizing criticality of the granular body. Due to this self-organized criticality, the failure form and scale of the granular slope are unpredictable when disturbed under the critical state. In this paper, it is considered that there are not only the movement of single or multiple particles on the surface of the granular slope, but also the mass instability of the whole body. On the basis of the extensive collection of domestic and foreign literature on the granular body and a large number of firsthand data on the spot, By means of theoretical derivation and physical simulation test, the geological hazard is studied from the point of view of geological hazard. The main contents include: (1) through field investigation and sampling and screening, the distribution characteristics, material composition, formation conditions and influencing factors of the granular slope are analyzed) and the contact between the granular particles is analyzed. By means of direct shear experiment, the characteristics of shear strength of particles are studied, and the effects of particle size and gradation on shear strength are analyzed. The active stages of granular slopes are divided, and the motion and failure modes of particles in the surface layer of granular slopes are clarified. The mechanical criterion of single particle starting is analyzed. The practicability of single particle starting criterion is verified by the experimental method, which is in good agreement with the experimental value, that is, the starting of a single regular particle in the surface layer is independent of the weight of the particle itself. The starting criterion of single particle can explain the separation of granular slope well. The results show that particle shape has a great influence on the starting condition of particles. (4) physical simulation of the whole deformation and failure mechanism is carried out, and three kinds of deformation and failure modes of granular slope, i.e. surface particle slip flow, are proposed. The stability evaluation of granular slope is further studied. In the aspect of stability evaluation method of granular slope, combined with physical simulation experiment, a method of judging stability is put forward according to the failure mode. According to the failure mode of surface particle sliding flow, the method of distinguishing key particles is proposed, and the traditional Bishop strip method is proposed for the failure mode of creep whole shearing.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43

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