SEISMOLOGY AND GEOLOGY ›› 2017, Vol. 39 ›› Issue (1): 81-91.DOI: 10.3969/j.issn.0253-4967.2017.01.006

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THE DISPLACEMENT AND STRESS FIELD GENERATED BY THE COLLAPSE IN PINGYI COUNTY, SHANGDONG PROVINCE, ON DECEMBER 25, 2015

WAN Yong-ge1, JIN Zhi-tong1, CUI Hua-wei1, HUANG Ji-chao1, SHENG Shu-zhong1, ZHANG Shan-shan1, LI Cui-qin2   

  1. 1. Institute of Disaster Prevention, Hebei Sanhe 065201, China;
    2. Earthquake Administration of Shandong Province, Jinan 250014, China
  • Received:2016-01-29 Revised:2016-04-26 Online:2017-02-20 Published:2017-04-26

2015年12月25日山东平邑塌陷事件产生的位移场与应力场

万永革1, 靳志同1, 崔华伟1, 黄骥超1, 盛书中1, 张珊珊1, 李翠芹2   

  1. 1. 防灾科技学院, 三河 065201;
    2. 山东省地震局, 济南 250014
  • 作者简介:万永革,男,1967年生,2001年在中国地震局地球物理研究所获得地震学博士学位,研究员,主要从事构造应力场、地震应力触发等方面的研究工作,E-mail:wanyg217217@vip.sina.com.cn,电话:010-58412460
  • 基金资助:

    国家自然科学基金(41674055)与河北省地震科技星火计划(DZ20170109001)共同资助

Abstract:

A collapse happened in Pingyi County, Shandong Province, on December 25, 2015. The displacement field, stress field and Coulomb failure stress change on the Mengshan frontal fault generated by the collapse are calculated by using point collapse model in isotropic medium. The result shows that: (1) The maximum horizontal displacement is located at the center of the collapse with value of~18mm. The horizontal displacements are greater than 1mm within~5km of the collapse with its direction pointing to the collapse center. The maximum subsidence is located at the center of the collapse with the value of 4mm. The subsidence is greater than 1mm within ~3km of the collapse. The displacement field decays so rapidly that can be ignored at far away from the collapse for the shallow source, which caused local displacement field. (2) Influenced by the free surface, the contraction area stress within ~5km of the collapse with the order of 1000Pa and expansion area stress in farther away areas at depth of 2km are estimated. the expansion area stress of 1000Pa is estimated at the~5km from the collapse center. Then the expansion area stress decays to 100Pa at the distance of ~10km from the collapse. The maximum compressive and extensional principal stresses are estimated as 10000Pa at the depth of 2km. The compressive stress axes present radical direction pointing to the collapse within ~5km of the center. In farther away from the collapse, The extensional principal stress axes present radical direction pointing to the center of the collapse. With farther distance to the collapse, the compressive and extensional stress decay rapidly to the order of 100Pa. (3) The Coulomb failure stress on the northwestern part of the Mengshan frontal fault, which is known as active segment of the Mengshan frontal fault, is decreased by the collapse with maximum value of 2500Pa. Whereas, the Coulomb failure stress on the southeastern part of the Mengshan frontal fault, which is known as left-lateral normal slip fault segment in Quaternary period, is increased by the collapse with maximum of 2400Pa, to which attention would be paid in seismic hazard analysis.

Key words: the 2015 Pingyi collapse in Shandong Province, displacement field, principal stress, Coulomb failure stress change, the Mengshan frontal fault

摘要:

2015年12月25日山东平邑县发生石膏矿塌陷事件。采用各向同性塌缩点源模型计算了该塌陷事件在周围地表产生的位移场、水平应力场及在其附近的蒙山山前断裂上的库伦破裂应力变化。结果表明:1)塌陷中心的水平位移达18mm,在距离塌陷位置约5km范围内的水平位移>1mm,方向指向塌陷中心;塌陷中心的垂直沉降达4mm,在塌陷中心约3km以内沉降>1mm,水平位移和垂直位移在远处快速衰减到可以忽略不计,这是由于该塌陷源较浅,位移变化局限在地表局部所致。2)由于自由表面的影响,该塌陷造成地下2km深度的约5km范围内呈现面收缩应力状态,面收缩应力达1000Pa;而在远处均处于面膨胀应力状态,膨胀应力最大约达1000Pa,面膨胀应力在距塌陷中心约10km处迅速衰减到100Pa以下。在2km深度的平面上造成的最大主张应力和主压应力达10000Pa,在主压应力大于主张应力的塌陷中心约5km范围内,主压应力呈现以塌陷为中心的径向分布,在距塌陷中心约5km以外,主张应力呈现以塌陷为中心的径向分布,随着距离的增大,主压应力和主张应力快速衰减到100Pa量级。3)该塌陷造成了其西北部的蒙山山前断裂(被认为不活动的断层段)上的库伦破裂应力降低,最大值达2500Pa,造成了东南部的蒙山山前断裂(被认为第四纪左旋正断活动的断层段)上的库伦破裂应力增加,最大值达2400Pa,在分析该断裂的危险性时要予以注意。

关键词: 2015年山东平邑塌陷, 位移场, 主应力, 库伦破裂应力变化, 蒙山山前断裂

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