本文選題：地震動模擬　切入點：經驗格林函數(shù)　出處：《中國地震局地球物理研究所》2015年碩士論文

【摘要】：近場強地面運動研究既是探尋震源特性及傳播介質信息的重要手段,也是確定某一地區(qū)地震動參數(shù)的衰減特征,并據(jù)此為抗震設計提供地震動參數(shù)的有效途徑。目前有工程意義的近場強震記錄數(shù)量仍然有限,但不斷新建的核電站、大型堤壩、超高層建筑等特殊設防類工程,其設計地震動參數(shù)對加速度反應譜及加速度時間過程又有明確要求。因此,開展大地震近場強地面運動數(shù)值模擬有潛在的應用價值及重要的科學意義。經驗格林函數(shù)方法是常用的地震動合成方法之一,其基本思想是用大震的前震或者余震作為經驗格林函數(shù)合成大震記錄。目前在應用經驗格林函數(shù)法模擬近場強地面運動時,通常假定所使用的有關參數(shù)都是確定的。而實際上,震源參數(shù)如大小地震斷層的長和寬、上升時間、斷層面破裂的位錯時間函數(shù)、斷層的起始破裂點、剪切波速、破裂傳播速度等,都有較大的不確定性,且這些參數(shù)的不確定性對模擬結果有顯著影響。本文考慮剪切波速、小震上升時間、破裂傳播速度及大小地震斷層長(寬)之比等參數(shù)不確定性對基于經驗格林函數(shù)法的強地面運動模擬結果的影響,將概率的方法應用于經驗格林函數(shù)法的模擬計算中,確定這四種參數(shù)的可能取值及其對應的概率,以邏輯樹的方式組合參數(shù)的可能取值及對應的概率,計算在不同情況下(參數(shù)組合)大震強地面運動的模擬結果及對應的概率,用統(tǒng)計的方法尋得最優(yōu)解,即為概率經驗格林函數(shù)法。論文開展了2013年4月20日蘆山地震(Ms=7.0)近場強地面運動模擬,模擬結果表明：由概率經驗格林函數(shù)法給出的峰值加速度、加速度時程、反應譜與實際大震記錄符合的比較好,從而驗證了該方法的可行性。另外,還分別研究了剪切波速、小震上升時間、破裂傳播速度及大小地震斷層長(寬)之比等每種參數(shù)的不確定性對2013年4月20日蘆山地震(Ms=7.0)的近場強地面運動模擬結果的影響程度。采用控制變量法研究了每個參數(shù)的不確定性對模擬結果的影響程度,結果表明：小震上升時間的不確定對模擬結果的影響不大；剪切波速、破裂傳播速度、大小地震長(寬)之比的不確定性對模擬結果影響明顯,其中大小地震長(寬)之比的不確定性對模擬結果的影響最為明顯。此外還研究了不同參數(shù)組合下模擬結果的實際誤差與估計誤差的分布情況,結果表明：使用考慮不確定性參數(shù)的概率經驗格林函數(shù)法能減小模擬結果的誤差。
[Abstract]:The study of near-field ground motion is not only an important means to search for the source characteristics and the information of transmitting medium, but also the attenuation characteristic of determining the ground motion parameters in a certain area. Based on this, the paper provides an effective way for seismic design to provide ground motion parameters. At present, the number of near-field strong earthquake records of engineering significance is still limited, but new nuclear power plants, large dams, super high-rise buildings and other special fortification projects are constantly being built. The design parameters of ground motion have definite requirements for acceleration response spectrum and acceleration time process. Numerical simulation of near-field ground motion of large earthquakes has potential application value and important scientific significance. Empirical Green's function method is one of the commonly used ground motion synthesis methods. The basic idea is to use the foreshocks or aftershocks of large earthquakes as empirical Green's function to synthesize the records of large earthquakes. At present, when the empirical Green's function is used to simulate the ground motion near the field strength, it is usually assumed that the relevant parameters used are determined. The source parameters, such as the length and width of large and small seismic faults, the rising time, the dislocation time function of fault plane rupture, the initial fracture point of the fault, the shear wave velocity, the fracture propagation velocity, etc., are all uncertain. The uncertainty of these parameters has a significant effect on the simulation results. In this paper, the shear wave velocity and the rise time of small earthquakes are considered. The influence of parameter uncertainty such as rupture propagation velocity and the ratio of length (width) of large and small earthquake faults on the simulation results of strong ground motion based on empirical Green's function method is studied. The probabilistic method is applied to the simulation calculation of empirical Green's function method. The possible values of these four parameters and their corresponding probabilities are determined, and the possible values and corresponding probabilities of the parameters are combined in a logical tree. The simulation results and the corresponding probabilities of the strong ground motions of large earthquakes under different conditions (parameter combinations) are calculated. The statistical method is used to find the optimal solution, that is, the probabilistic empirical Green's function method. In this paper, the ground motion simulation of the Lushan earthquake on April 20, 2013 (MsN 7.0) is carried out. The simulation results show that the peak acceleration is obtained by the probabilistic empirical Green's function method. The acceleration time history and the response spectrum are in good agreement with the actual earthquake records, which verifies the feasibility of the method. In addition, the shear wave velocity and the rise time of small earthquakes are studied respectively. The degree of influence of the uncertainty of each parameter, such as rupture propagation velocity and the ratio of length (width) of large and small earthquakes to the Lushan earthquake of April 20, 2013, on the ground motion simulation results of near-field strength is studied by using the control variable method. The degree to which uncertainty of the parameters affects the simulation results, The results show that the uncertainty of the rise time of small earthquakes has little effect on the simulation results, while the uncertainty of shear wave velocity, fracture propagation velocity and the ratio of length (width) of large and small earthquakes have obvious effects on the simulation results. The uncertainty of the ratio of magnitude to width has the most obvious effect on the simulation results. In addition, the distribution of the actual error and the estimation error of the simulation results under different parameter combinations are also studied. The results show that the method of probabilistic empirical Green's function with uncertain parameters can reduce the error of simulation results.
【學位授予單位】：中國地震局地球物理研究所
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU352.11;P315.9

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