【作者】 程海英；

【导师】 张武；

【作者基本信息】 上海大学 ， 计算机应用技术， 2008， 博士

【摘要】 活动断层是引起地震发生的根源。地震灾害是群灾之首。因地震的突发性和不可抗拒性,从而产生巨大危害。大量的震害资料表明,地震时沿断层线的破坏最为严重,人员伤亡也明显地大于断层两侧的其它区域。十五期间,国家投巨资在全国24个大中城市开展城市活断层探测与地震危害性评价工作。淄博市重点活动断裂(张店-仁河断裂)近断层危害场数值模拟属山东省地震局“十五”重点项目计划。本文所完成的主要工作有:(一)首先搜集日本和我国台湾等地典型地震的研究资料,对典型地震活断层近断层危害性影响场进行初步分析;分析和比较近断层地震动的研究方法;总结了近断层强地震动特征,包括上盘效应、竖向效应、破裂方向性效应以及滑冲效应等等。(二)在淄博市活断层探测和地震小区划研究的基础上,建立了淄博市重点活动断裂(张店-仁河断裂)地震危害性评价的地质-构造三维结构模型。在实际模拟时,根据隐伏断层位置、上断点埋深以及介质分层,共考虑了五个试验段,并针对每一个试验段不同倾角、不同倾向的情况分别建立了三维地质模型,包括大规模计算的地质模型在内总共十六个模型。特别是在模拟土的性质时采用了摩尔-库伦模型进行计算,与以往的仅仅采用弹性模型计算相比,更符合实际。(三)采用显式拉格朗日有限差分法,通过对每一个试验段的不同倾角、不同倾向的七种模型施加不同的地震波荷载,得到了张店-仁河断裂近断层地震危害场的数值模拟结果,包括各种情况下的变形场、应力场、位移场和加速度场,数值模拟结果均以图形化的方式显示出来。由于显式拉格朗日有限差分法在求解运动基本方程过程中,不需要形成总刚度矩阵,而是在每一个时间步修正坐标,位移增量加到坐标上,使网格移动和材料变形,每一步本构公式是小应变,但在很多步之后等价于大应变公式。计算结果能表现出接触块体相互运动和变形的特征,并且由于不解总刚度方程,便于在计算机上实现,计算速度快,占用存储空间小。(四)本论文给出了基于区域分解算法的一种有限元并行算法,先将偏微分方程求解区域划分为若干个子区域,然后在各个子区域并行求解。结合大型稀疏矩阵方程组的并行共轭梯度算法,编制了基于Linux操作系统,适用于PC集群的并行有限元计算程序,来对第四章所建立的地质模型进行计算模拟,得到了张店-仁河断裂近断层地震危害场的数值模拟结果,并行程序大大节省了计算时间,具有很好的加速比。由于有限元法更适用于空间变化复杂的介质,能够便利地处理自由表面,精确计算面波的传播,计算精度高。很适宜在分布式内存的PC集群上方便地进行并行计算,因此对于大规模模型可以提高计算速度,非常适用于大规模地球介质模型地震波动场数值计算。(五)通过对有限差分与有限元模拟结果的分析检验,计算结果与近断层强地震动基本特征的吻合,较好的反映了近断层强地震动的盆地效应、方向性效应、上盘效应等基本特征,验证了我们模拟结果的合理性和方法的可信性,同时也证明了震源模型与传播介质模型建立和参数设置的合理性。本文的计算结果可以为防震减灾和工程设计提供指导和参考。另外,模拟中还存在需要进一步改进和加强研究的地方。例如,需要在建立三维地震构造模型方面多做研究,地震构造模型的科学性如何,直接制约、影响到计算结果,其中任何一个参数的变动,将会导致产出结果变化。因此,地震地表变形带的预测是一项综合性很强的工作,需要不同的专业的科研人员的密切配合。但作者相信,这些都会随着资料的积累和研究的深入逐步得到解决,使近断层强地震动模拟更加完善。更多还原

【Abstract】 Active fault is the root cause to earthquake.Disaster Earthquake is in the first place of disasters.Earthquake is unexpected and irresistible,so it can have tremendous harm.A lot of damage data indicate that earthquakes along the fault lines make the most serious damage,casualties is obviously greater than other regions on both sides of the fault.During the 10th Five-Year Plan period,China invested in the 24 large and medium-sized cities in urban areas to active fault detection and evaluation of seismic danger.The numerical simulation of near-fault endangered field of the focus active faults in Zibo City(Zhangdian-Renhe fault) against near-fault is a priority "Ten-five" project of Shandong Seismological Bureau.The main works completed in this paper include:1) The typical seismic data of many districts is collected,such as Japan and Taiwan,and preliminary analysis of the typical active Near-fault endangered field is made.The research methods of the near-fault ground motion are systemically reviewed and compared.The basic characteristics of near-fault ground motion are summarized,such as the hanging wall effect,the vertical effect,the rupture directivity effect,the fling step effect and so on.2) Based on the correlative data and geology information of moderate and upwards earthquakes of Zibo City,sixteen 3D geology models of the main active fault of Zibo City(Zhangdian-Renhe Fault) are created according to the nearby and on the base of active fault detection and the small-area earthquake analyses.Especially, Moore-Coulomb model is used in the simulation of the nature of soil,it is more realistic than only adopting a flexible model in the past.3) Explicit Lagrangian finite difference method is adopted because it is needn’t to form the stiffness matrix in solving the basic equation of the process of movement. Numerical simulations of the near-fault disservice field are performed.The simulation results,including the various circumstances deformation,stress,displacement,and acceleration field,numerical simulation results are graphically displayed.The results can show the characteristics of mutual contact blocks’ movement and deformation, and because of the stiffness puzzling equation in the computer easy to achieve, calculation is fast and taking up small storage space.4) In this paper,a FEM parallel algorithm based on a domain decomposition algorithm is given,parallel finite element calculation procedure based on Linux operating system is developed for PC cluster.Through the simulation calculation to the geological models established in ChapterⅣ,the numerical simulation results are got.The procedure has a good parallel speedup.The finite element method(FEM) is more suitable to the medium with complex space changes,more convenient to deal with the free surface,and it can get accurate calculation of wave propagation.FEM is very suitable for the PC cluster with distributed memory,can increase the calculation speed for large-scale Earth’s medium model.5) Through the analysis of the simulation results,it is obviously that the results better reflect the basic features of near-fault seismic,such as the basin effect,the vertical effect,the hanging wall effect,and so on.The results can provide guidance and reference for Earthquake Disaster Mitigation and engineering design.In addition,it is necessary to further improve and research more on many aspect of simulation.For example,more research is needed in building three-dimensional structural model of the earthquake,because the scientific nature of the seismic model constraints and affects the calculated results directly,any of these parameters change, the results will change.Therefore,prediction of surface deformation zone in earthquake is a very complex task,it is required that different professional research staff cooperated closely.With the accumulation of information and in-depth research, these will be gradually resolved and the simulation of near-fault ground motion will be more complete.更多还原