| The regional tectonic activity is caused due to the earth’s crust tectonic movement form of physical activity, which can affect the formation and change of a regional geomorphic and provided the impetus for crustal activity. The occurrence of geological disasters is also closely connected with the regional tectonic activities.In the tectonic system of mainland china, the loess plateau is located in central china area that tectonic activities and geological disasters are active and frequent in cenozoic era. The typical area is Weihe basin which is located in the junction of the east margin of Qinghai-tibet and Ordos massif, geological disaster is frequent because of the active tectonic activities, the most widely and typical are ground fissures and earthquake disasters. In addition, Ganqing block is as same as Weihe basin where geological disasters occured, the most serious disaster is Loess landslide. Therefore, the research of the earth’s crust tectonic movement and deformation and the mechanism of hazards in this area has important theoretical and practical significance, we can grasp the evolution of the crustal tectonic activity area, their relationship of geological disasters and the geological disaster prevention and mitigation.This article adopts the method of finite element analysis, using the high precision regional GPS monitoring data as constraint conditions and examining condition to construct the Weihe basin area of two-dimensional plane model and three-dimensional lithosphere model framework with the comprehensive multi-disciplinary theory and data. We can calculate the model to get the characteristics of tectonic activity, and combined with the regional crustal movement and deep dynamic process to discuss the mechanism of regional tectonic activities, fault tectonic activity features, then analyse the inner link of geological disaster and regional tectonic activities. In addition, this article also take the typical disaster area as an example which is located in Heifangtai Loess Plateau, by the finite element numerical simulation method to study the mechanism of the instability and failure of landslides caused by self-supporting and soil saturation, getting the changes in different stages of the landslide, and analysis the slope displacement of measuring points, preliminary studying the rule of the irrigation type loess landslide instability, deepening the understanding of the evolution of landslide disaster. In this paper, the main research contents and results are as follows:(1) Introduce the research of geodetic surveying technology and the modern geodetic methods on the earth’s crust, and emphatically introduces the theory of the finite element and the application of the crustal deformation simulation.(2) By using regional geological conditions, fault data, material parameters, and using GPS displacement monitoring results as constraint conditions, build the two-dimensional plane model and three-dimensional crustal model of Weihe basin, calculate the displacement of the model, and compared the GPS measurements as examining condition for the reliability of the test model, to get the relative reliable model.(3) Studying the crustal tectonic activity characteristics of Weihe basin by the finite element model, getting the character of the activity of regional active faults and the fracture stress characteristics, then can find its power information from deep, discussed the inner relationship of regional structure and the geological disasters.(4) Take the typical monomer loess landslide as the research object, using the finite element strength subtraction for stability calculation, it got the landslide sliding plastic changes in different stages, then make the study of the mechanism of the landslide instability, and combining the on-the-spot investigation to study the slope surface displacement change trend of opening, preliminary understanding the instability and failure of landslide evolution caused by self-supporting and soil saturation. |
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