【作者】 刘孙君；

【导师】 熊熊； 王勇；

【作者基本信息】 中国科学院研究生院（测量与地球物理研究所） ， 固体地球物理学， 2003， 硕士

【摘要】 地壳的运动和变形是各种地球动力学过程在地表的综合显现，是地壳介质对板块构造和深部动力过程作用的综合响应，因此，对地壳运动和变形的研究构成了地球动力学研究的重要内容之一。传统上，一般用地质和地震学方法来确定地壳的运动和变形特征，但二者确定的地壳形变结果分别是百千万年和百年左右的平均结果，难以描述现今地壳运动和变形的特征。而以全球定位系统(GPS)等技术为主的大地测量方法弥补了地质和地震学方法在时间维上的不足，但大地测量方法存在测点覆盖不足及测点地理分布不均匀的缺点，因此，要得到连续的地壳形变场有必要借助数值模拟方法。 本文首先简要介绍了有限元数值方法的基本思想和弹性力学问题中有限元分析的一般过程。以GPS观测结果为边界约束，利用有限元分析软件ANSYS模拟了青藏高原及临区的地壳运动位移场，应力场和应变场，并在模型上从边界的选取，断层的引入及精细的网格划分三个方面做了改进。然后将数值结果与其它观测研究结果作了较全面的比对，其吻合程度是较好的，结果表明模型及解算结果是合理和可靠的。 本文最后在数值结果的基础上对青藏高原现今构造应力场特征及阿尔金断裂的左旋走滑速率做了初步的探讨。首先分析了模拟的应力场，从应力结果图可以看出青藏高原尤其是喜马拉雅块体上东—西或近东—西的拉张应力呈现了较明显的主导趋势，本文对这一特征从印度和欧亚板块的汇聚，区域上地幔对流以及高原巨大的重力势能三个方面的作用做了解释，结果表明青藏高原现今的应力场的形成是多种动力学过程作用的结果。其次从模拟的位移场结果计算了阿尔金断裂现今的左旋走滑速率为8mm／a左右，这一结果与青藏高原地壳缩短及被吸收的“地壳增厚”动力学模式预测的断层走滑速率相符，表明地壳增厚模式可能是高原现今构造的主要格局。更多还原

【Abstract】 The movement and deformation of the crust are the comprehensive effects of various kinds of the geodynamical processes on the ground, and the systematical response of the crustal medium to the plate tectonic and deeply dynamic evolution. Therefore, the research for them becomes one of important contents in the geodynamic studies. The characteristics of the movement and deformation of the crust were traditionally determined with the geological and seismographic methods. However, the result obtained with the geological and seismographic methods is virtually an average one on the time scale of millions and/or hundreds of years, and the current movement and deformation of the crust cannot be described well. Fortunately, the modern geodetic measurements such as the Global Positioning System (GPS) technique can overcome the shortage of the geological and seismographic methods in the time dimension; and yet, the coverage of the geodetic survey stations is not sufficient. As a result, it is necessary to employ numerical simulation to investigate the continuous deformation of the crust.The principles of the finite-element method and the general process of the finite-element analysis in the elastic mechanics are simply introduced at first hi this thesis. The finite-element software, called the ANSYS, is used to simulate the displacement, stress and strain fields of the crustal movement in the Tibetan Plateau and its near region with the boundary constraint of the GPS observations. Moreover, the choice of the boundaries, introduction of the faults and generation of the meshes have been improved while creating the model. The numerical results obtained in this study are closed accordance with the other corresponding results obtained by some authors. It implies that the model and the numerical results are reasonable and reliable.Based on the numerical results, the present characteristics of the tectonic stress field in the Tibetan Plateau and the rate of left-lateral slip of the Altyn Tagh fault are primarily discussed in this thesis. From the figure of the simulated stress field, it is found that the east-west or nearly east-west tensile stress is dominant in the Tibetan Plateau, especially on the Himalaya block. This characteristic is explained with three stress fields, which are generated by combined actions of the Indian and Eurasia plate collision, the regional upper mantle convection and the giant gravitational potentialenergy. It is suggested that the current stress field in the Tibetan plateau is a result of the combined actions of various kinds of dynamic evolution. From the simulated displacement field, the left-lateral strike-slip rate on the Altyn Tagh fault is evaluated as about 8mm/a, which accords with the one predicted by the dynamic model that tries to explain the contract and absorbency of the crutal substance in the plateau. It shows that the dynamic model may be dominant to the crustal movement and deformation in the Tibetan plateau today.更多还原