基于有限元法的区域构造活动与地质灾害数值模拟研究

发布时间：2018-03-16 10:46

本文选题：渭河盆地　切入点：甘肃黑方台　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：区域地壳构造活动是由于地壳内部构造运动引起的物质活动形式,影响地区地貌的形成和变化,以及为地壳运动与形变提供动力基础,而地质灾害的发生往往也与区域地壳构造活动密不可分。在中国大陆构造体系中,位于大陆中部的黄土高原区域,新生代以来构造活动活跃,地质灾害频发,比较典型的区域是位于青藏东缘与鄂尔多斯地块交界处的渭河盆地,现今地壳构造活动十分活跃,导致地质灾害频发尤以地裂缝、地震灾害最为广泛和典型。此外,与渭河盆地成一脉体系的甘青区域也是地质灾害多发区,以黄土滑坡灾害最为严重。因此,开展上述区域地壳构造运动与变形、地质灾害发生机制的研究,对掌握区域现今地壳构造活动的演化及其与地质灾害相互关系、地质灾害防治减灾等具有有重要的理论和现实意义。基于此,本文采用有限元数值分析方法,以高精度GPS监测资料做为约束与检核条件,综合多学科基础理论与地质地球物理资料,构建了渭河盆地地区二维与三维有限元模型,获得了渭河盆地区域现今地壳构造活动特征,并结合区域地壳运动与深部动力学过程探讨了区域性构造活动机制、断层构造活动特性,以及深入剖析了研究域地质灾害发生与区域构造活动的内在联系。此外,以甘青地区最为典型的黑方台黄土滑坡灾害为例,利用有限元数值模拟法分自重作用和水土饱和度两类情况下,研究了黄土滑坡失稳破坏的机制,获得了滑坡各阶段变形情况,并对坡面测点进行了位移折线图分析,初步获得了灌溉型黄土滑坡失稳普遍规律,加深了对滑坡灾害演化的理解。本文主要的研究内容及成果如下:(1)详细论述了大地测量技术在区域构造活动及地质灾害研究中的应用,重点介绍了有限元法在地壳构造活动及地质灾害模拟研究中的优势。(2)利用区域地质地球物理勘测成果,以边界区域高精度GPS监测成果作为地表及边界约束,建立了渭河盆地地壳二维与三维有限元模型,并以模型内部实测GPS位移作为检核条件,验证了模型的可靠性。(3)利用构建的渭河盆地有限元模型,反演获得了渭河盆地现今地壳构造活动特征,及区域内主干断裂现今活动速率与不同深度断裂应力变化特征,并结合区域构造动力学背景,探讨了区域构造活动与地裂缝、地震灾害的内在关系。(4)以典型黄土滑坡为研究对象,利用有限元强度折减法分别在自重与水土饱和度条件下对滑坡稳定性进行了模拟计算,获得了滑坡滑动过程中各阶段塑性变化特征,并结合实地考察资料研究了坡体临空面位移变化趋势,初步掌握了滑坡失稳破坏演化机理。
[Abstract]:Regional crustal tectonic activity is a form of material activity caused by tectonic movement within the crust, which affects the formation and change of landforms in the region, and provides a dynamic basis for crustal movement and deformation. The occurrence of geological hazards is often closely related to the regional crustal tectonic activities. In the continental tectonic system of China, the Loess Plateau region in the middle of the continent has been active in tectonic activity since the Cenozoic, and geological disasters occur frequently. The typical area is the Weihe basin located at the junction of the eastern margin of Qinghai-Tibet and the Ordos block. The crustal tectonic activity is very active, which leads to frequent geological disasters, especially the ground fractures, and the earthquake disaster is the most extensive and typical. The Gansu and Qing regions, which form the same vein system as Weihe Basin, are also prone to geological disasters, especially the loess landslide. Therefore, the study on the crustal tectonic movement, deformation and the mechanism of geological hazards in the above-mentioned regions is carried out. It is of great theoretical and practical significance to understand the evolution of the present crustal tectonic activity and its relationship with geological hazards, and to prevent and reduce geological disasters. Based on this, the finite element numerical analysis method is used in this paper. Taking the high precision GPS monitoring data as the constraint and checking condition, the two-dimensional and three-dimensional finite element models of Weihe Basin are constructed by synthesizing the multidisciplinary basic theory and geological geophysical data. The characteristics of present crustal tectonic activity in Weihe basin are obtained, and the regional tectonic active mechanism and fault tectonic active characteristics are discussed in combination with regional crustal movement and deep dynamic process. In addition, taking Heifangtai loess landslide disaster in Ganqing area as an example, the inherent relationship between geological hazards and regional tectonic activities in the study area is deeply analyzed. In this paper, the mechanism of loess landslide instability and failure is studied by using finite element numerical simulation method, which is divided into two types: deadweight action and soil and water saturation, and the deformation of landslide in different stages is obtained, and the displacement profile of the measured points on the slope is analyzed. The general law of instability of irrigated loess landslide is obtained preliminarily. The main contents and results of this paper are as follows: (1) the application of geodetic technology in the study of regional tectonic activities and geological hazards is discussed in detail. The advantage of finite element method in the study of crustal tectonic activity and geological hazard simulation is emphatically introduced. Using the regional geophysical survey results, the high-precision GPS monitoring results in the boundary area are taken as the surface and boundary constraints. The two-dimensional and three-dimensional finite element models of the crust of Weihe basin are established, and the GPS displacement measured inside the model is used as the check condition to verify the reliability of the model. The characteristics of present crustal tectonic activity in Weihe basin, the present active rate of main faults and the stress variation of faults at different depths in Weihe basin are obtained by inversion. Combined with the regional tectonic dynamic background, the regional tectonic activity and ground fractures are discussed. Taking the typical loess landslide as the research object, the stability of the landslide is simulated by using the finite element strength reduction method under the condition of gravity and water and soil saturation, respectively. The characteristics of plastic variation in each stage of landslide sliding are obtained, and the trend of displacement change on the face of slope is studied with field investigation data, and the evolution mechanism of landslide instability and failure is preliminarily grasped.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P548;P694

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