﻿ 基于二维有限单元法的芦山M7.0地震近场强地面运动模拟
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 大地测量与地球动力学  2019, Vol. 39 Issue (2): 131-136  DOI: 10.14075/j.jgg.2019.02.005

引用本文

MENG Qingxiao, LÜ Jian, JING Pengxu. Simulation of Near Field Strong Ground Motion of Lushan M7.0 Earthquake Based on Two-Dimensional Finite Element Method[J]. Journal of Geodesy and Geodynamics, 2019, 39(2): 131-136.

Foundation support

The Earthquake Emergency Task of CEA, No.CEA_EDEM-201817; The Spark Program of Earthquake Technology of CEA, No. XH14067Y;Combination Project with Monitoring, Prediction and Scientific Research of Earthquake Technology, CEA, No.CEA.JC3JH-163707.

第一作者简介

MENG Qingxiao, PhD candidate, engineer, majors in earthquake engineering, E-mail:mengqingxiao09@mails.ucas.ac.cn.

文章历史

1. 中国地震局第一监测中心，天津市耐火路7号，300180;
2. 中国地震局地球物理研究所，北京市民族大学南路5号，100081;
3. 中国地震局地震研究所，武汉市洪山侧路40号，430071;
4. 中国地震应急搜救中心，北京市玉泉西街1号，100049

2013-04-20 08:02四川芦山发生M7.0地震(30.3°N，103.0°E)，造成188人死亡、25人失踪、1万多人受伤，经济损失达数百亿元，近场震害尤为严重[1]。然而，芦山地震近场范围内仅有宝兴和名山两个强震观测台站[2]，强震观测资料的有限性导致难以有效刻画近场强地面运动特征。

1 方法与模型 1.1 发震断层接触模型

 图 1 接触单元示意图 Fig. 1 The sketch diagram of contact element

 图 2 接触单元本构关系 Fig. 2 Constitutive relation of the contact element
1.2 边界条件处理

1.3 芦山地震有限元模型

 图 3 芦山地震近场构造综合信息 Fig. 3 The comprehensive information of the near field area of the Lushan earthquake

 图 4 芦山地震近场区A-A′剖面二维几何模型及P波、S波速度结构 Fig. 4 The deep reflection profile, P wave and S wave tomography results of the near field of the Lushan M7.0 earthquake

2 讨论与分析 2.1 信度检验

 图 5 芦山地震中宝兴台(51BXD)及名山台(51YAM) FN和UD方向地震动加速度观测波形 Fig. 5 The observation results of ground motion acceleration waveforms at Baoxing (51BXD) station and Mingshan (51YAM) station in Lushan earthquake

 图 6 芦山地震中宝兴台(51BXD)及名山台(51YAM)地震动加速度时程模拟结果 Fig. 6 The simulation results of ground motion acceleration waveforms at Baoxing (51BXD) station and Mingshan (51YAM) station in Lushan earthquake

 图 7 宝兴台水平地震动观测波、模拟波以及NGA-West2设定波形组的加速度反应谱(阻尼比5%) Fig. 7 The acceleration response spectrum of the observation wave, the simulation wave and the NGA-West2 waveform group of the Baoxing station(damping ratio 5%)

 图 8 名山台水平地震动观测波、模拟波以及NGA-West2设定波形组的加速度反应谱(阻尼比5%) Fig. 8 The acceleration response spectrum of the observation wave, the simulation wave and the NGA-West2 waveform group of the Mingshan station(damping ratio 5%)

2.2 震源参数的影响作用

 图 9 应力降参数对水平向基岩地震动峰值加速度的影响 Fig. 9 The influence of stress drop parameters on peak acceleration of horizontal bedrock ground motion

 图 10 应力降参数对水平向基岩地震动加速度反应谱的影响 Fig. 10 The influence of stress drop parameters on acceleration response spectrum of horizontal bedrock ground motion

 图 11 粘聚力参数对水平向基岩地震动峰值加速度的影响 Fig. 11 The influence of cohesive parameters on peak acceleration of horizontal bedrock ground motion

 图 12 粘聚力参数对水平向基岩地震动加速度反应谱的影响 Fig. 12 The influence of cohesive parameters on acceleration response spectrum of horizontal bedrock ground motion

3 结语

1) 应力降和粘聚力均对地表水平向基岩地震动具有显著的正向影响作用，应力降增大导致近场峰值加速度增大更为明显，而粘聚力增大则会导致相对远场处峰值加速度增加更为明显。

2) 应力降对0.05~1.00 s频域范围内的短周期地震动成分影响较为明显，粘聚力则对1.00~6.00 s频域范围内的中长周期地震动成份具有显著影响。

3) 不同应力降和粘聚力参数条件下，发震断层上盘场址处水平地震动峰值加速度明显大于下盘场址处水平地震动峰值加速度，且具有相对更慢的地震动衰减速度，呈现出典型的上下盘效应特征。

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Simulation of Near Field Strong Ground Motion of Lushan M7.0 Earthquake Based on Two-Dimensional Finite Element Method
MENG Qingxiao1,2,3     LÜ Jian1,3     JING Pengxu4
1. The First Monitoring and Application Center, CEA, 7 Naihuo Road, Tianjin 300180, China;
2. Institute of Geophysics, CEA, 5 South-Minzudaxue Road, Beijing 100081, China;
3. Institute of Seismology, CEA, 40 Hongshance Road, Wuhan 430071, China;
4. National Earthquake Response Support Agency, 1 West-Yuquan Street, Beijing 100049, China
Abstract: According to the geophysical data obtained in the near field of the Lushan M7.0 earthquake in 2013, including the deep reflection profile and the result of P wave and S wave tomography, we establish the two-dimensional finite element model. The contact element is used to simulate the discontinuous behavior of the faults, and the numerical simulation results of the strong ground motion are further given. The results show that the ground motion parameters on hanging walls are larger than those on footwalls at the similar rupture distances, which we call the hanging-wall/foot-wall effects of near-fault ground motions. At the same time, the stress drop and cohesive force parameters have obvious positive effects on ground surface horizontal bedrock ground motion. The stress drop plays a significant role in the short period components in 0.05 s-1.00 s, and cohesion has a significant effect on the medium and long period components of 1.00 s-6.00 s.
Key words: finite element method; near field strong ground motion; Lushan earthquake; hanging-wall/foot-wall effects; focal parameters