地震地质 ›› 2023, Vol. 45 ›› Issue (5): 1200-1218.DOI: 10.3969/j.issn.0253-4967.2023.05.010

• 研究论文 • 上一篇    下一篇

逆断层上覆土层地表破裂影响因素的数值模拟

郭婷婷1,2)(), 徐锡伟3,4), 袁仁茂5), 杨宏智6)   

  1. 1) 山东省地震工程研究院, 济南 250021
    2) 山东省地震局, 济南 250014
    3) 中国地质大学(北京), 北京 100083
    4) 应急管理部国家自然灾害防治研究院, 北京 100085
    5) 中国地震局地质研究所, 地震与火山灾害重点实验室, 北京 100029
    6) 山东省物化探勘查院, 济南 250013
  • 收稿日期:2022-12-30 修回日期:2023-03-08 出版日期:2023-11-23 发布日期:2023-11-23
  • 作者简介:

    郭婷婷, 女, 1979年生, 2013年于中国地震局地质研究所获构造地质学专业博士学位, 高级工程师, 主要从事岩土力学与工程、 活动构造学及其在减轻地震灾害中的应用研究工作, E-mail:

  • 基金资助:
    中国地震局地震科技星火计划项目(XH20035); 国家自然基金委资助项目(41941016); 国家自然基金委资助项目(V1839204)

NUMERICAL SIMULATION OF INFLUENCING FACTORS OF SURFACE RUPTURE IN OVERLYING SOIL LAYER OF THRUST FAULT

GUO Ting-ting1,2)(), XU Xi-wei3,4), YUAN Ren-mao5), YANG Hong-zhi6)   

  1. 1) Earthquake Risk Prevention and Control Center of Shandong Province, Jinan 250021, China
    2) Earthquake Administration of Shandong Province, Jinan 250014, China
    3) China University of Geosciences, Beijing 100083, China
    4) National Institute of Natural Hazards, Ministry of Emergency Management of the People's Republic of China, Beijing 100085, China
    5) Key Laboratory of Seismic and Volcano Hazards, Institute of Geology, China Earthquake Administration, Beijing 100029, China
    6) Shandong Institute of Geophysical and Geochemical Exploration, Jinan 250013, China
  • Received:2022-12-30 Revised:2023-03-08 Online:2023-11-23 Published:2023-11-23

摘要:

强震发生时, 震源断层错动引发上覆土体变形破裂是地面建(构)筑物破坏的重要原因。为研究和分析上覆土层地表变形与破裂特征及其影响因素, 文中通过有限元数值模拟方法, 综合分析断层倾角、 断层错动位移量、 上覆土层厚度对上覆土层地表变形与破裂的影响及其规律。结果表明: 1)断层垂直位错量为上覆土层厚度的3.3%、 倾角仅为30°时, 发生地表破裂; 断层垂直位错量为上覆土层厚度的5%、 倾角为30°、 45°时, 发生地表破裂; 断层垂直位错量为上覆土层厚度的6.6%、 倾角为30°、 45°、 70°时, 发生地表破裂; 断层垂直位错量为上覆土层厚度的10%、 倾角为30°、 45°、 70°与逼近90°时, 均发生地表破裂。2)随垂直位错量的增加或上覆土层厚度与断层倾角的减小, 地表等效应变逐渐变大, 越容易发生地表破裂。3)随着断层倾角由30°、 45°增加至70°, 上、 下盘地表破裂宽度比值从约3︰1增加至3︰2~1︰1。4)上覆土层的变形与破裂, 首先始于断层基岩与土体交界面的土体破裂, 随着位错量的增加, 当断层倾角为30°、 45°、 70°时, 地表均出现了1个初始破裂点; 当断层倾角逼近90°时, 地表出现了2个初始破裂点, 最后上覆土层出现贯通破裂。

关键词: 数值模拟, 逆断层, 上覆土层地表破裂, 断层倾角, 垂直位错量, 等效有效应变

Abstract:

When the strong earthquakes occur, the deformation and rupture of overlying soil caused by the dislocation of focal faults is one of the important reason for the destruction of ground structures. In the process of a strong earthquake or large earthquake, the deformation reaction and failure of the overlying soil of underground concealed faults are very complicated. To study and analyze the characteristics and influencing factors of surface deformation and fracture of the overlying soil layer, in this paper, the influences of fault dip Angle, fault displacement, and overlying soil thickness on surface deformation and fracture of overlying soil are analyzed by the finite element numerical simulation method comprehensively. The results show that: 1)With the increase of fault vertical dislocation of 1m to 4m, the surface equivalent strain gradually increases, the surface rupture is more likely to occur, and the surface rupture width also wider. With the increase of the thickness of the overlying soil layer from 20m to 60m, and the increase of the fault inclination from 30°, 45°, 70° to nearly 90°, the surface equivalent strain is gradually smaller, the surface rupture is more likely to occur, and the surface fracture width becomes smaller, which means that the amount of dislocation required for the same rupture state needs to increase. 2)When the vertical dislocation of the fault is about 3.3%for the thickness of the overlying soil, the surface rupture occurs only as the fault dip angle is 30°, no surface rupture occurs as the dip angle is 45° and 70°. When the vertical dislocation of the fault is about 5% of the thickness of the overlying soil, the surface rupture occurs only as the fault dip angle is 30° and 45°, no surface rupture occurs as the dip angle is 70° and approaching 90°. When the vertical dislocation of the fault is about 6.6% of the thickness of the overlying soil, the surface rupture occurs as the fault dip angle is 30°、 45° and 70°, and surface rupture is expected to occur as the dip angle is approaching 90°. When the vertical dislocation of the fault is about 10% of the thickness of the overlying soil, the surface rupture occurs as the fault dip angle is 30°, 45°, 60°and approaching 90°. 3)When the amount of vertical dislocation and the thickness of the overlying soil are certain, the ratio of surface rupture width between the hanging wall and footwall which is less affected by fault dip ranges from 3︰1 to 3︰2~1︰1 with the increase of fault dip Angle from 30°, 45° to 70°. When the fault inclination Angle is 30°, with a decrease of vertical dislocation of 4m to 1m, or the increase of overlying soil layer thickness of 20m to 60m, the ratio of surface rupture width between hanging wall and footwall is slightly larger from about 3︰1. When the fault inclination Angle is 45°, with the decrease of vertical dislocation of 4m to 1m, or the increase of overlying soil layer thickness of 20m to 60m, the ratio of surface rupture width between hanging wall and footwall is slightly larger from about 2︰1. When the fault inclination Angle is 75°, with the decrease of vertical dislocation of 4m to 1m, or the increase of overlying soil layer thickness of 20m to 60m, the ratio of surface rupture width between hanging wall and footwall is slightly larger from about 3︰2~1︰1. Under the above fault dip conditions, the ratio of surface rupture width between hanging wall and footwall is less affected by the amount of vertical dislocation and the thickness of overlying soil. As the inclination is approaching 90°, the ratio of surface rupture width between the hanging wall and footwall is about 1︰1, which is not affected by the vertical dislocation and the thickness of the overlying soil layer. 4)The deformation and fracture of the overlying soil layer first began with the soil fracture at the interface of the fault bedrock and soil. With the increase in the amount of dislocation, a fracture point appeared on the surface when the fault dip Angle was 30°, 45°, and 70°. However, when the dip Angle of the fault was close to 90°, there were two initial rupture points on the surface. With the increase of vertical dislocation or the decrease of the overlying soil layer thickness, the overlying soil layer through fracture is finally formed.

Key words: Numerical simulation, thrust fault, overlying soil failure, fault dip angle, vertical dislocation quantity, equivalent effective strain