三峡库区动水压力型滑坡对降雨的响应规律：以八字门滑坡为例

刘开心; 邓茂林; 费霈妍; 易庆林; 汪标

doi:10.19509/j.cnki.dzkq.tb20240697

三峡库区动水压力型滑坡对降雨的响应规律：以八字门滑坡为例

doi: 10.19509/j.cnki.dzkq.tb20240697

三峡大学湖北省地质灾害防治工程技术研究中心，湖北宜昌 443002

基金项目: 国家自然科学基金面上项目（42172303）

详细信息

作者简介:
刘开心：E-mail：1589036623@qq.com

通讯作者:
E-mail：624350911@qq.com

中图分类号: P642.22
计量
- 文章访问数: 343
- PDF下载量: 28
- 被引次数: 0
出版历程
- 收稿日期: 2024-11-18
- 录用日期: 2025-03-25
- 修回日期: 2025-03-19
- 网络出版日期: 2025-03-26

Response patterns of dynamic water pressure-induced landslides in the Three Gorges Reservoir area to rainfall: A case study of the Bazimen landslide

Hubei Engineering Technology Research Center for Disaster Prevention and Mitigation, China Three Gorges University, Yichang Hubei 443002, China

More Information

Author Bio:
E-mail：1589036623@qq.com

Corresponding author: E-mail：624350911@qq.com

摘要

摘要:
为探究动水压力型滑坡对降雨的响应规律，以三峡库区八字门滑坡为例，结合地质勘察数据、相关性分析及有限元数值模拟，系统研究了降雨对滑坡变形的影响，揭示其对降雨的响应规律及变形机制。研究表明，库水位涨落和降雨是八字门滑坡变形的主要驱动因素。降雨对滑坡变形的影响表现为：在库水位下降阶段，降雨通过补给坡体内部水头，进一步增强动水压力作用，显著加剧坡体变形；而在库水位上升阶段，降雨入渗至次级滑带后缘，导致孔隙水压力升高，从而引发滑坡后缘变形并推动滑坡整体变形，足够的降雨是库水位上升期间滑坡变形的主要触发因素。滑坡变形呈现一定的滞后性，其中库水位下降引发的变形滞后时间约为20 d，降雨引发的变形滞后时间为9 d。长时间持续降雨条件下的滑坡稳定系数（1.029）衰减程度高于暴雨条件下的稳定系数（1.039）。研究成果深化了对动水压力型滑坡变形机制的认识，可为该类滑坡的预警预测提供参考。
- 八字门滑坡 /
- 动水压力 /
- 库水调度 /
- 降雨 /
- 稳定性 /
- 三峡库区
Abstract: Objective
This study aims to explore the response patterns of dynamic water pressure-induced landslides to rainfall.
Methods
Taking the Bazimen landslide in the Three Gorges Reservoir area as an example, this study systematically investigated the influence of rainfall on landslide deformation by integrating geological survey data, correlation analysis, and finite element numerical simulation, revealing its response patterns to rainfall and deformation mechanisms.
Results
The results showed that fluctuations in reservoir water level and rainfall were the main driving factors of the deformation of the Bazimen landslide. The impact of rainfall on landslide deformation was manifested as follows. During the reservoir water level falling stage, rainfall replenished the internal water head of the slope, further enhancing the effect of dynamic water pressure and significantly aggravating slope deformation. During the reservoir water level rising stage, rainfall infiltrated into the rear edge of the secondary sliding zone, which caused an increase in pore water pressure; this in turn triggered deformation at the rear edge of the landslide and further led to overall deformation of the landslide. Adequate rainfall was the main triggering factor of landslide deformation during the reservoir water level rising stage. The landslide deformation exhibited a certain lag, with a lag time of about 20 days for deformation caused by reservoir water level drawdown and 9 days for deformation caused by rainfall. The attenuation degree of the landslide stability coefficient (1.029) under conditions of long-duration continuous rainfall was higher than that of the coefficient under conditions of rainstorm (1.039).
Conclusion
The research findings deepen the understanding of the deformation mechanisms of dynamic water pressure-induced landslides and can provide insights into the early warning and prediction of such landslides
- Bazimen landslide /
- dynamic water pressure /
- reservoir water scheduling /
- rainfall /
- stability /
- Three Gorges Reservoir area

HTML全文

图 1 八字门滑坡全貌图(a)、剖面图(b)及平面图(c)

Figure 1. Overview (a), profile (b), and plan view (c) of the Bazimen landslide

下载: 全尺寸图片幻灯片

图 2 八字门滑坡监测点累计位移−降雨量−库水位−时间关系曲线

a. ZG110，ZG111人工监测点；b. GSC1～5，7～9人工监测点；c. GSCX3，GSCX5，ZGX111全自动监测点

Figure 2. Relationship curves between cumulative displacement, rainfall, reservoir water level, and time at monitoring points of the Bazimen landslide

下载: 全尺寸图片幻灯片

图 3 不同滑坡变形阶段监测点位移−库水位−降雨量−时间关系曲线

Figure 3. Relationship curves between displacement, reservoir water level, rainfall, and time at monitoring points during different landslide deformation stages

下载: 全尺寸图片幻灯片

图 4 八字门滑坡数值模型

Figure 4. Numerical model of the Bazimen landslide

下载: 全尺寸图片幻灯片

图 5 滑坡渗流

Figure 5. Landslide seepage

下载: 全尺寸图片幻灯片

图 6 滑带后缘孔隙水压

Figure 6. Pore water pressure at rear edge of sliding zone

下载: 全尺寸图片幻灯片

图 7 2019年11月1日−2020年10月31日位移场

Figure 7. Displacement field from Dovember 1, 2019 to October 31, 2020

下载: 全尺寸图片幻灯片

图 8 模拟位移曲线

Figure 8. Simulated displacement curves

下载: 全尺寸图片幻灯片

图 9 稳定系数（J₁, J₂, J₃. 降雨工况编号，见表4）

Figure 9. Stability coefficient

下载: 全尺寸图片幻灯片

表 1 阶跃信息统计

Table 1. Statistic of step information

变形时间	库水位		降雨		GSCX3监测点平均形变速率/(mm·d⁻¹)
变形时间	水位/m	升降速率/(m·d⁻¹)	降雨时间	降雨量/mm	GSCX3监测点平均形变速率/(mm·d⁻¹)
2016/06/25−2016/07/09	146.5～150.53	0.27	2016/06/24−2016/07/01	153.8	5.93
2017/07/07−2017/07/23	154.6～150.42	−0.25	2017/07/07−2017/07/17	198.6	2.8
2017/09/27−2017/10/26	164.26～174.59	0.34	2017/09/27−2017/10/14	260.8	5.85
2018/07/07−2018/07/14	148.26～148.18	−0.01	2018/07/05	57	1.48
2021/07/09−2021/07/17	146.63～146.9	0.003	2021/07/02−2021/07/09	111	5.87

下载: 导出CSV

表 2 GSCX3监测点形变速率与有效降雨相关性分析

Table 2. Correlation analysis between displacement rate and effective rainfall at monitoring point GSCX3

	有效降雨天数/d	当天	3	6	7	8	9	10
形变速率	皮尔逊相关性	0.030	0.322**	0.510**	0.522**	0.527**	0.529**	0.526**
	显著性（双尾）	0.002	0.000	0.000	0.000	0.000	0.000	0.000
	个案数	1691	1691	1691	1691	1691	1691	1691
注：**. 在 0.01 级别（双尾），相关性显著

下载: 导出CSV

表 3 滑坡物理力学参数

Table 3. Physical and mechanical parameters of landslides

区域	重度 γ/(kN·m⁻³)	黏聚力 c/kPa	内摩擦角φ/(°)	饱和体积含水率W/%	渗透系数 K/(m·d⁻¹)
初生滑体	22	17.6	20.5	23	0.01
次级滑体1	22	13	12	30.9	0.1
次级滑体2	21	14	18	30.9	0.1
初生滑带	21.3	15	21	30	0.001
次级滑带	18.5	10	17	25	0.005
滑床	28	255	32	10	0.001

下载: 导出CSV

表 4 降雨工况设置详情

Table 4. Details of rainfall conditions setting

工况	工况内容
J₁	库水位由175 m以0.6 m/d的速率降至160 m，再以1 m/d的速率降至145 m并保持低水位30 d。并在水位降至160 m施加10 a一遇降雨，持续9 d
J₂	库水位由175 m以0.6 m/d的速率降至160 m，再以1 m/d的速率降至145 m并保持低水位30 d。并在水位降至160 m施加50 a一遇降雨，持续9 d
J₃	库水位由175 m以0.6 m/d的速率降至160 m，再以1 m/d的速率降至145 m并保持低水位30 d。并在水位降至160 m施加10 a一遇降雨，持续14 d

下载: 导出CSV

参考文献(40)

[1]	谢媛华, 张国伟, 曹宗伟, 等. 三峡库区白水河滑坡位移与裂缝分形特征[J]. 地质科技通报, 2024, 43(4): 244-251. doi: 10.19509/j.cnki.dzkq.tb20230166 XIE Y H, ZHANG G W, CAO Z W, et al. Fractal characteristics of displacement and cracks in the Baishuihe landslide in the Three Gorges Reservoir area[J]. Bulletin of Geological Science and Technology, 2024, 43(4): 244-251. (in Chinese with English abstract doi: 10.19509/j.cnki.dzkq.tb20230166
[2]	TANG H M, YONG R, EZ ELDIN M A M. Stability analysis of stratified rock slopes with spatially variable strength parameters: The case of Qianjiangping landslide[J]. Bulletin of Engineering Geology and the Environment, 2017, 76(3): 839-853. doi: 10.1007/s10064-016-0876-4
[3]	卫童瑶, 殷跃平, 高杨, 等. 三峡库区巫山县塔坪H1滑坡变形机制[J]. 水文地质工程地质, 2020, 47(4): 73-81. WEI T Y, YIN Y P, GAO Y, et al. Deformation mechanism of the Taping H1 landslide in Wushan County in the Three Gorges Reservoir area[J]. Hydrogeology & Engineering Geology, 2020, 47(4): 73-81. (in Chinese with English abstract
[4]	LIAO K, WU Y P, MIAO F S. System reliability analysis of reservoir landslides: Insights from long-term reservoir operation[J]. Journal of Earth Science, 2024, 35(5): 1583-1593. doi: 10.1007/s12583-022-1668-3
[5]	李钰, 陈明亮, 黄会宝, 等. 新华滑坡变形演化规律与预警判据[J]. 地质科技通报, 2024, 43(3): 227-239. LI Y, CHEN M L, HUANG H B, et al. Deformation evolution law and early warning criterion of Xinhua landslide[J]. Bulletin of Geological Science and Technology, 2024, 43(3): 227-239. (in Chinese with English abstract
[6]	LI B Y, WANG G L, CHEN L C, et al. Analysis of landslide deformation mechanisms and coupling effects under rainfall and reservoir water level effects[J]. Engineering Geology, 2024, 343: 107803. doi: 10.1016/j.enggeo.2024.107803
[7]	MA S Y, SHAO X Y, XU C. Physically-based rainfall-induced landslide thresholds for the Tianshui area of Loess Plateau, China by TRIGRS model[J]. Catena, 2023, 233: 107499. doi: 10.1016/j.catena.2023.107499
[8]	龚泉冰, 殷坤龙, 肖常贵, 等. 基于I-D阈值的滑坡气象预警双指标模型[J]. 地质科技通报, 2024, 43(1): 262-274. doi: 10.19509/j.cnki.dzkq.tb20220254 GONG Q B, YIN K L, XIAO C G, et al. Double-index model of landslide meteorological warning based on the I-D threshold[J]. Bulletin of Geological Science and Technology, 2024, 43(1): 262-274. (in Chinese with English abstract doi: 10.19509/j.cnki.dzkq.tb20220254
[9]	汪标, 易庆林, 邓茂林, 等. 降雨与库水作用下谭家河滑坡变形响应规律分析[J]. 人民长江, 2023, 54(4): 141-149. WANG B, YI Q L, DENG M L, et al. Analysis on deformation response law of Tanjiahe landslide induced by rainfall and reservoir water[J]. Yangtze River, 2023, 54(4): 141-149. (in Chinese with English abstract
[10]	YANG L, WANG Y, CAO Y, et al. Revealing the characteristics and type of chair-shaped landslides considering the reservoir water effect in the Three Gorges Reservoir area, China[J]. Bulletin of Engineering Geology and the Environment, 2024, 83(5): 155. doi: 10.1007/s10064-024-03603-2
[11]	KANG J, WAN B C, GAO Z Q, et al. Research on machine learning forecasting and early warning model for rainfall-induced landslides in Yunnan Province[J]. Scientific Reports, 2024, 14: 14049. doi: 10.1038/s41598-024-64679-0
[12]	许冲, 戴福初, 姚鑫, 等. 基于GIS与确定性系数分析方法的汶川地震滑坡易发性评价[J]. 工程地质学报, 2010, 18(1): 15-26. doi: 10.3969/j.issn.1004-9665.2010.01.003 XU C, DAI F C, YAO X, et al. GIS platform and certainty factor analysis method based Wenchuan earthquake-induced landslide susceptibility evaluation[J]. Journal of Engineering Geology, 2010, 18(1): 15-26. (in Chinese with English abstract doi: 10.3969/j.issn.1004-9665.2010.01.003
[13]	WANG D Y, ZHU H H, ZHOU G Y, et al. Monitoring shear deformation of sliding zone via fiber Bragg grating and particle image velocimetry[J]. Journal of Rock Mechanics and Geotechnical Engineering, 2024, 16(1): 231-241. doi: 10.1016/j.jrmge.2023.03.007
[14]	BOLLA A, PARONUZZI P, PINTO D, et al. Mineralogical and geotechnical characterization of the clay layers within the basal shear zone of the 1963 Vajont landslide[J]. Geosciences, 2020, 10(9): 360. doi: 10.3390/geosciences10090360
[15]	黄润秋, 裴向军, 崔圣华. 大光包滑坡滑带岩体碎裂特征及其形成机制研究[J]. 岩石力学与工程学报, 2016, 35(1): 1-15. doi: 10.13722/j.cnki.jrme.2015.0075 HUANG R Q, PEI X J, CUI S H. Cataclastic characteristics and formation mechanism of rock mass in sliding zone of Daguangbao landslide[J]. Chinese Journal of Rock Mechanics and Engineering, 2016, 35(1): 1-15. (in Chinese with English abstract doi: 10.13722/j.cnki.jrme.2015.0075
[16]	李守定, 李晓, 吴疆, 等. 大型基岩顺层滑坡滑带形成演化过程与模式[J]. 岩石力学与工程学报, 2007, 26(12): 2473-2480. doi: 10.3321/j.issn:1000-6915.2007.12.012 LI S D, LI X, WU J, et al. Evolution process and pattern of sliding zone in large consequent bedding rock landslide[J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 26(12): 2473-2480. (in Chinese with English abstract doi: 10.3321/j.issn:1000-6915.2007.12.012
[17]	ZHU R S, XIE W L, LIU Q Q, et al. Shear behavior of sliding zone soil of loess landslides via ring shear tests in the South Jingyang Plateau[J]. Bulletin of Engineering Geology and the Environment, 2022, 81(6): 244. doi: 10.1007/s10064-022-02719-7
[18]	邓茂林, 周剑, 易庆林, 等. 三峡库区靠椅状土质滑坡变形特征及机制分析[J]. 岩土工程学报, 2020, 42(7): 1296-1303. doi: 10.11779/CJGE202007013 DENG M L, ZHOU J, YI Q L, et al. Characteristics and mechanism of deformation of chair-shaped soil landslides in Three Gorges Reservoir area[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(7): 1296-1303. (in Chinese with English abstract doi: 10.11779/CJGE202007013
[19]	ABEYGUNASEKARA H, KAZAMA S, SAMARASURIYA C. Numerical modeling of landslide susceptibility: A case study for Uma Oya catchment, Sri Lanka[J]. Journal of JSCE, 2023, 11(2): 23-27036.
[20]	WANG G H, WATANABE N, HOSHIKAWA K, et al. Diverse shear behaviors of clayey materials: Implications for differing landsliding behaviors within the same area in Niigata, Japan[J]. Engineering Geology, 2023, 312: 106932. doi: 10.1016/j.enggeo.2022.106932
[21]	LIU Q Q, PAN M H, WANG X L, et al. A two-layer model for landslide generated impulse wave: Simulation of the 1958 Lituya Bay landslide impact wave from generation to long-duration transport[J]. Advances in Water Resources, 2021, 154: 103989. doi: 10.1016/j.advwatres.2021.103989
[22]	XUE Z H, FENG W K, LI B T, et al. Landslide susceptibility mapping based on the coupling of two correlation methods and the BP neural network model: A case study of the Baihetan Reservoir area, China[J]. Frontiers in Environmental Science, 2022, 10: 1039985. doi: 10.3389/fenvs.2022.1039985
[23]	王进, 臧明东, 许冲, 等. 基于层次分析与受试者工作特征曲线下面积耦合算法的2022年泸定地震滑坡易发性评估[J]. 工程地质学报, 2024, 32(5): 1696-1711. WANG J, ZANG M D, XU C, et al. Landslide susceptibility assessment following the 2022 Luding earthquake: A coupled analytic hierarchy process and area under the receiver operating characteristic curve algorithm[J]. Journal of Engineering Geology, 2024, 32(5): 1696-1711. (in Chinese with English abstract
[24]	SPIEKERMANN R I, SMITH H G, MCCOLL S, et al. Development of a morphometric connectivity model to mitigate sediment derived from storm-driven shallow landslides[J]. Ecological Engineering, 2022, 180: 106676. doi: 10.1016/j.ecoleng.2022.106676
[25]	黄发明, 叶舟, 姚池, 等. 滑坡易发性预测不确定性: 环境因子不同属性区间划分和不同数据驱动模型的影响[J]. 地球科学, 2020, 45(12): 4535-4549. HUANG F M, YE Z, YAO C, et al. Uncertainties of landslide susceptibility prediction: Different attribute interval divisions of environmental factors and different data-based models[J]. Earth Science, 2020, 45(12): 4535-4549. (in Chinese with English abstract
[26]	SAMODRA G, NGADISIH, NUGROHO F S. Benchmarking data handling strategies for landslide susceptibility modeling using random forest workflows[J]. Artificial Intelligence in Geosciences, 2024, 5: 100093. doi: 10.1016/j.aiig.2024.100093
[27]	毛佳, 王舒鹤, 邵琳玉, 等. 索风营水电站Dr2岩质边坡渐进破坏全过程数值模拟[J/OL]. 工程科学与技术: 1-13[2026-02-04]. https://link.cnki.net/urlid/51.1773.TB.20240819.0930.009. MAO J, WANG S H, SHAO L Y, et al. Numerical simulation of the whole process of progressive damage of Dr2 rocky slope in the Suofengying hydropower station[J/OL]. Advanced Engineering Sciences: 1-13[2026-02-04]. https://link.cnki.net/urlid/51.1773.TB.20240819.0930.009. (in Chinese with English abstract
[28]	李世海, 刘天苹, 刘晓宇. 论滑坡稳定性分析方法[J]. 岩石力学与工程学报, 2009, 28(增刊2): 3309-3324. LI S H, LIU T P, LIU X Y. Analysis method for landslide stability[J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28(S2): 3309-3324. (in Chinese with English abstract
[29]	毛彦龙, 胡广韬, 毛新虎, 等. 地震滑坡启程剧动的机理研究及离散元模拟[J]. 工程地质学报, 2001, 9(1): 74-80. doi: 10.3969/j.issn.1004-9665.2001.01.013 MAO Y L, HU G T, MAO X H, et al. Mechanism of set-out violent-slide of slope mass during earthquake and its simulation by using discrete element method[J]. Journal of Engineering Geology, 2001, 9(1): 74-80. (in Chinese with English abstract doi: 10.3969/j.issn.1004-9665.2001.01.013
[30]	邓茂林, 易庆林, 韩蓓, 等. 长江三峡库区木鱼包滑坡地表变形规律分析[J]. 岩土力学, 2019, 40(8): 3145-3152. doi: 10.16285/j.rsm.2018.0809 DENG M L, YI Q L, HAN B, et al. Analysis of surface deformation law of Muyubao landslide in Three Gorges Reservoir area[J]. Rock and Soil Mechanics, 2019, 40(8): 3145-3152. (in Chinese with English abstract doi: 10.16285/j.rsm.2018.0809
[31]	开迪尔丁·吾拉木, 张紫昭, 张艳阳, 等. 基于COMSOL Multiphysics的降雨型滑坡临界降雨阈值计算模型研究: 以新疆新源县喀拉海依苏滑坡隐患体为例[J]. 工程地质学报, 2023, 31(4): 1364-1374. KAIDIERDING W L M, ZHANG Z Z, ZHANG Y Y, et al. COMSOL Multiphysic based calculation model of critical rainfall threshold for rainfall-induced landslide: A case study of Karahayisu landslide in Xinyuan County, Xinjiang[J]. Journal of Engineering Geology, 2023, 31(4): 1364-1374. (in Chinese with English abstract
[32]	殷跃平, 张晨阳, 闫慧, 等. 三峡水库蓄水运行滑坡渗流稳定和防治设计研究[J]. 岩石力学与工程学报, 2022, 41(4): 649-659. doi: 10.13722/j.cnki.jrme.2021.0674 YIN Y P, ZHANG C Y, YAN H, et al. Research on seepage stability and prevention design of landslides during impoundment operation of the Three Gorges Reservoir, China[J]. Chinese Journal of Rock Mechanics and Engineering, 2022, 41(4): 649-659. (in Chinese with English abstract doi: 10.13722/j.cnki.jrme.2021.0674
[33]	李锦平. 浅析八字门滑坡的发展原因[J]. 西部探矿工程, 2006(增刊1): 508-509. doi: 10.3969/j.issn.1004-5716.2006.z1.263 LI J P. Analysis on the development causes of Bazimen landslide[J]. West-China Exploration Engineering, 2006(S1): 508-509. (in Chinese with English abstract doi: 10.3969/j.issn.1004-5716.2006.z1.263
[34]	ZHANG K, ZHANG K, CAI C X, et al. Displacement prediction of step-like landslides based on feature optimization and VMD-Bi-LSTM: A case study of the Bazimen and Baishuihe landslides in the Three Gorges, China[J]. Bulletin of Engineering Geology and the Environment, 2021, 80(11): 8481-8502. doi: 10.1007/s10064-021-02454-5
[35]	TU P F, WU S C, LI H T. Analysis of Bazimen landslide deformation based on GPS[J]. Advanced Materials Research, 2011, 347/353: 435-439.
[36]	邓茂林, 易庆林, 卢书强, 等. 三峡库区靠椅状土质滑坡变形规律及机理: 以秭归八字门滑坡为例[J]. 南水北调与水利科技(中英文), 2020, 18(2): 135-143. DENG M L, YI Q L, LU S Q, et al. Study on the deformation law and mechanism of chair-shaped soil landslide in Three Gorges Reservoir area: Taking the landslide of Bazimen in Zigui as an example[J]. South-to-North Water Transfers and Water Science & Technology, 2020, 18(2): 135-143. (in Chinese with English abstract
[37]	ZHOU C, YIN K L, CAO Y, et al. Application of time series analysis and PSO-SVM model in predicting the Bazimen landslide in the Three Gorges Reservoir, China[J]. Engineering Geology, 2016, 204: 108-120. doi: 10.1016/j.enggeo.2016.02.009
[38]	张桂荣, 程伟. 降雨及库水位联合作用下秭归八字门滑坡稳定性预测[J]. 岩土力学, 2011, 32(增刊1): 476-482. doi: 10.16285/j.rsm.2011.s1.052 ZHANG G R, CHENG W. Stability prediction for Bazimen landslide of Zigui County under the associative action of reservoir water lever fluctuations and rainfall infiltration[J]. Rock and Soil Mechanics, 2011, 32(S1): 476-482. (in Chinese with English abstract doi: 10.16285/j.rsm.2011.s1.052
[39]	郭飞, 黄晓虎, 邓茂林, 等. 三峡库区“阶跃” 型滑坡变形机理与预警模型[J]. 测绘学报, 2022, 51(10): 2205-2215. GUO F, HUANG X H, DENG M L, et al. Study on deformation mechanism and warning model of step-like landslide in Three Gorges Reservoir area[J]. Acta Geodaetica et Cartographica Sinica, 2022, 51(10): 2205-2215. (in Chinese with English abstract
[40]	ZHANG W G, TANG L B, LI H R, et al. Probabilistic stability analysis of Bazimen landslide with monitored rainfall data and water level fluctuations in Three Gorges Reservoir, China[J]. Frontiers of Structural and Civil Engineering, 2020, 14(5): 1247-1261. doi: 10.1007/s11709-020-0655-y