平原区深层隐伏岩溶的重力正演模拟
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摘要
岩溶塌陷一般发生在覆盖层较薄的地区,深层岩溶塌陷虽较少见,但若发生在城市建筑密集区其危害极大。为研究北京东部地区深层岩溶发育的地质条件,对不同尺度的岩溶风化壳和溶洞可能产生的重力异常响应进行了正演模拟,结果表明:厚覆盖层地区开展微重力测量识别一定规模的岩溶是可行的,覆盖层厚度大于200m、半径小于2m的空洞将难以通过微重力方法直接识别出来;岩溶空洞引起重力异常的幅值与其半径、埋深及内部充填物的密度有关;实测剖面长度应大于岩溶风化壳宽度或空洞直径,且需要在实测重力异常中准确去除覆盖层的影响。
Karst collapse usually occurs in the areas with thin covered strata. Although deep burial karst collapse is rare, it will be extremely harmful when it is located in densely populated areas of urban buildings. In order to study the geological conditions of deep burial karst in the eastern part of Beijing and to prevent the risk of collapse, it is necessary to carry on the gravity forward modeling research on weathering crust and cavity. Based on the gravity forward modeling, the gravity anomaly response characteristics of different scales have been obtained. The results show that:(1) it is feasible to identify a certain scale karst by high-precision gravity survey in thick burial karst areas, however, it is difficult to directly identify the karst cavities with a thickness of more than 200 m and a radius of less than 2 m by microgravity method;(2) The amplitude of gravity anomaly caused by karst cavity is related to its radius, buried depth and the density of internal fillings;(3) To effectively identify the karst cavity, the length of gravity profile should be larger than the width of karst weathering crust or the cavity's diameter, and the influence of the covered strata should be accurately removed from the measured gravity anomaly data.
Karst collapse usually occurs in the areas with thin covered strata. Although deep burial karst collapse is rare, it will be extremely harmful when it is located in densely populated areas of urban buildings. In order to study the geological conditions of deep burial karst in the eastern part of Beijing and to prevent the risk of collapse, it is necessary to carry on the gravity forward modeling research on weathering crust and cavity. Based on the gravity forward modeling, the gravity anomaly response characteristics of different scales have been obtained. The results show that:(1) it is feasible to identify a certain scale karst by high-precision gravity survey in thick burial karst areas, however, it is difficult to directly identify the karst cavities with a thickness of more than 200 m and a radius of less than 2 m by microgravity method;(2) The amplitude of gravity anomaly caused by karst cavity is related to its radius, buried depth and the density of internal fillings;(3) To effectively identify the karst cavity, the length of gravity profile should be larger than the width of karst weathering crust or the cavity's diameter, and the influence of the covered strata should be accurately removed from the measured gravity anomaly data.
引文
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钟立勋,2001.谨防京郊平原发生深层隐伏岩溶塌陷[J].中国地质灾害与防治学报,12(4):26-29.
Pearson-Grant S C, Franz P, Clearwater J, 2018. Gravity measurements as a calibration tool for geothermal reservoir modelling[J]. Geothermics. 73:146-157.
胡瑞林,王思敬,李焯芬,等,2001.唐山市岩溶塌陷区域风险评价[J].岩石力学与工程学报,20(2):180-180.
雷晓东,姚春梅,邵景力,等,2010.临沂市城区岩溶塌陷危险性控制[J].地学前缘,17(6):271-277.
李巧灵,雷晓东,李晨,2018.抗干扰编码电法在通州深部岩溶发育区地质构造探测中的应用[J].工程勘察,(2):71-78.
廖海军,马志飞,2015.北京市海淀区普安店地区岩溶塌陷灾害成因分析及防治对策[J].城市地质,10(Sl):218-221.
石建省,1996.唐山市活动性断裂与岩溶塌陷关系的空间分析[J].中国地质灾害与防治学报,(3):87-91.
石亚雄,孙少安,吴丽华,等,1991.微重力测量在溶洞探测中的应用[J].物探与化探,15(6):468-470.
王谦身,周文虎,武传真,等,1995.微重力方法在考古工程中的应用——明茂陵地下陵殿探查[J].地球物理学进展,10(2):85-94.
王延涛,潘瑞林,2012.微重力法在采空区勘查中的应用[J].物探与化探,36(S1):61-64.
杨进,2011.环境与工程地球物理[M].北京:地质出版社.
袁炳强,刘士毅,于国明,等,2015.秦始皇帝陵遗址考古重磁力场特征[J].地球科学(中国地质大学学报),(10):1616-1620.
赵博超,朱蓓,王弘元,等,2015.浅谈岩溶塌陷的影响因素与模型研究[J].中国岩溶,34(5):515-521.
钟立勋,2001.谨防京郊平原发生深层隐伏岩溶塌陷[J].中国地质灾害与防治学报,12(4):26-29.
Pearson-Grant S C, Franz P, Clearwater J, 2018. Gravity measurements as a calibration tool for geothermal reservoir modelling[J]. Geothermics. 73:146-157.