基于GPS观测的青藏高原东缘应力应变场研究

发布时间：2018-06-28 16:12

本文选题：构造应力场 + GPS　；参考：《长安大学》2015年硕士论文

【摘要】：在众多自然灾害中,地震灾害以其突发性和不可预测性对人类生活影响最大。通过地震学家长期对地震的研究发现,一般认为它由地球内部的岩体受到内部应力影响,致使岩体突然断裂错动而产生,最终造成地表不同程度的形变和破坏。随着空间测量技术的发展,利用GPS技术能够精确获取地壳动态形变和构造应力场变化,结合地质和地球物理资料,探求强震孕育、发生及发展规律,从而最大限度的降低地震灾害。青藏高原东缘地质构造复杂,活动强烈。本文以青藏高原东缘作为研究区域,利用多期GPS观测数据,从地壳形变和块体断裂的角度分析了地震引发的块体应变场及构造应力场变化特征,探求其活动断裂的运动方式;与此同时,利用边界元法对川滇地块构造应力场进行计算,模拟区域地震演化特征,结合该区域地质背景资料,探求汶川地震诱发因素及其驱动力源。论文主要工作与成果如下:1.以GPS数据为基础,利用整体旋转线性应变法和多面函数法分别模拟了青藏高原东缘地壳形变及区域应力场变化特征,研究块体运动趋势及内部应变场变化,阐述了构造应力场特征与地质结构分布和地震活动的关系,两种方法体现出较好的一致性。2.青藏高原东缘构造应力场以南北向压应力为主,东西向拉张力为辅,印度板块向北推压和欧亚板块向南推进迄今仍起主控作用。其位移场总体上由南向北呈逐渐减小趋势,主应力主要在四川、云南区域高度集中。同期的强震也主要发生在应力高度集中、剪切应变值变化范围大和具有深大断层区域。3.基于边界元算法验证了地壳内部介质参数对区域构造应力场结果的影响。研究表明:在力边界条件不变的情况下,改变泊松比值将会影响位移场和构造应力场的结果;改变弹性模量值,仅改变位移场结果,而不改变应力场结果。弹性模量大,位移值小,应变量也减小,应力值变大,反之也成立。4.利用边界单元数值模拟法对川滇地区地壳形变和深部动力机制进行了分析,探求龙门山断裂带深部构造特征与汶川地震的诱发因素及驱动力源。认为其主要来自印澳板块与欧亚大陆碰撞及向北挤压、青藏高原向东运移延伸遭遇华南板块阻挡,应力场及能量高度集中导致地壳表面发生破裂、内部断裂发生错动而造成的。
[Abstract]:Among many natural disasters, earthquake disaster has the greatest impact on human life because of its sudden and unpredictability. Through the seismologists' long-term research on earthquake, it is generally believed that it is caused by the internal stress of the rock mass inside the earth, resulting in the sudden fracture and dislocation of the rock mass, resulting in different degrees of deformation and destruction of the surface of the earth. With the development of space survey technology, the dynamic crustal deformation and tectonic stress field changes can be accurately obtained by using GPS technology. Combined with geological and geophysical data, the law of strong earthquake preparation, occurrence and development can be explored. In order to minimize the earthquake disaster. The eastern margin of Qinghai-Xizang Plateau is characterized by complex geological structure and strong activity. Taking the eastern margin of the Qinghai-Xizang Plateau as the study area and using the multi-period GPS observation data, the variation characteristics of the earthquake induced block strain field and tectonic stress field are analyzed from the point of view of crustal deformation and block faults, and the movement mode of its active faults is explored. At the same time, the boundary element method is used to calculate the tectonic stress field of Sichuan-Yunnan block, to simulate the evolution characteristics of regional earthquakes, and to explore the induced factors and driving force sources of Wenchuan earthquake combined with the regional geological background data. The main work and results are as follows: 1. Based on GPS data, the variation characteristics of crustal deformation and regional stress field in the eastern margin of Qinghai-Xizang Plateau are simulated by using the integral rotation linear strain method and the multi-plane function method, respectively, and the trend of block movement and the variation of internal strain field are studied. The relationship between the characteristics of tectonic stress field and the distribution of geological structure and seismic activity is expounded. The tectonic stress field in the eastern margin of the Qinghai-Xizang Plateau is dominated by the south-north compressive stress supplemented by the east-west tension. The thrust of the Indian plate to the north and the Eurasian plate to the south still play a dominant role so far. The displacement field decreases gradually from south to north, and the principal stress is mainly concentrated in Sichuan and Yunnan regions. The strong earthquakes in the same period also mainly occurred in the high stress concentration, the range of shear strain change was large and the area with deep fault was .3. Based on the boundary element algorithm, the influence of the medium parameters in the crust on the results of the regional tectonic stress field is verified. The results show that changing Poisson ratio will affect the results of displacement field and tectonic stress field when the force boundary condition is invariant, and change the elastic modulus value, only change the displacement field result, but not change the stress field result. The elastic modulus is large, the displacement value is small, the strain variable is also reduced, and the stress value is increased. The crustal deformation and deep dynamic mechanism in Sichuan-Yunnan area are analyzed by using boundary element numerical simulation method, and the deep structural characteristics of Longmenshan fault zone and the inducing factors and driving force sources of Wenchuan earthquake are explored. It is considered that the collision between the Indo-Australian plate and the Eurasian continent and the northward compression, the eastward migration of the Qinghai-Xizang Plateau is blocked by the South China plate, and the stress field and the high concentration of energy lead to the rupture of the crustal surface and the dislocation of the internal fracture.
【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】：P228.4;P315.727

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