RAINFALL INFILTRATION MECHANISMS OF SOIL COLUMNS UNDER CONDUCTIVITY
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摘要: 我国东南沿海地质环境复杂脆弱,由台风暴雨引发的滑坡频频发生。雨水入渗到土体内可能导致坡体变形,进而产生滑坡、泥石流等灾害。以福建三明岩兜滑坡为研究对象,通过自行研制的人工降雨土柱入渗试验装置,对研究区滑坡的残积土柱进行了不同降雨强度下(20 mm·h-1、60 mm·h-1)的累次循环降雨实验,考虑了不同降雨量、降雨历时和雨停时间等工况,获得了干湿循环下土柱含水率、电阻率以及基质吸力变化等丰富的降雨入渗试验数据,并与现场原型测试结果验证。研究结果表明:(1) 累次降雨中,土柱上部传感器含水率峰值随着干湿循环次数增加缓慢降低,深部的土体则在累次降雨后,土体含水量逐渐累积,含水率峰值缓慢提高。(2) 原状土柱土体具有非均质性,不同深度土体电阻率大小不一。电阻率响应时间与含水率响应时间具有高度相关性,含水率变化时电阻率也几乎同时产生变化,但两者变化趋势相反。(3) 基质吸力在累次降雨雨停阶段回升缓慢,多次降雨过程中,由于前次降雨中留下的水分未完全排干,基质吸力在多次降雨的作用下降到0 kPa。(4) 基于Keller改进的Archie拓展模型对研究区土体电阻率含水率进行拟合,并用实测数据进行验证,误差较小。进一步结合Archie拓展模型与Green-Ampt、Philip入渗模型,得到基于电阻率的Green-Ampt与Philip入渗模型。研究成果有助于进一步揭示研究区降雨作用下坡残积土的电阻率演化规律,揭示坡残积土坡在累次降雨下的水分入渗规律,对台风暴雨型滑坡稳定性分析及监测预警具有重要的理论及实际意义。Abstract: The geological environment of China's southeast coast is complex and fragile,with frequent landslides triggered by typhoons and rainstorms. The key factor that leads to the deformation of the slope body,then landslide and mudslide is the rainwater infiltration into the soil. This paper studies the landslide in Yandou Village. It is located in the east of Fujian Province. The study uses a self-developed artificial rainfall soil columns infiltration experiment device. It considers different rainfall,rainfall duration,rainfall interval time,and other working conditions. It conducts different cumulative cyclic rainfall experiments on the slope residual soil of landslides at different rainfall intensities(20 and 60 mm·h-1). The experiments give the rainfall infiltration data,including changes in water content,resistivity,and matric suction of soil under drying and wetting circles. The analysis of the test results show the following findings. (1) Under cumulative rainfall circumstances,the peak water content of the upper soil slowly decreases with the increase of wet and dry cycles times,while the deeper soil gradually accumulates water content and the peak water content slowly increases. (2) The soil columns feature heterogeneity. Different depths of soil show various resistivity. There is a highly correlation between the resistivity response time and the water content response time. The resistivity changes almost simultaneously when the water content changes,but these changing indicators are on the contrary. (3) The matric suction represents a very limited recovery during the rain-stopping phase of the cumulative rainfall. From the second rainfall,due to the water of the last rainfall still remaining in the soil,the matric suction drops to 0 kPa after cumulative rainfall. (4) The errors can be smaller using the expansion Archie model modified by Keller to conduct resistivity and water content fitting in the research area. This paper combined the expansion Archie model,the Green-Ampt model,and the Philip infiltration model to obtain the Green-Ampt and Philip infiltration model based on resistivity. This provides a new measurement perspective for soil infiltration with practical value. The results of this study contribute to exploring further the resistivity evolution of slope residual soils under the action of typhoons and rainstorms in the research area. In addition,the achievements reveal rainfall infiltration mechanisms of slope residual soil under cumulative rainfall circumstances that are of important theoretical and practical significance to analyze the stability of typhoon and rainstorm type landslides and to monitor and early warning activities.
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Key words:
- Rainfall /
- Residual soil /
- Resistivity /
- Matric suction /
- Infiltration
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图 9 残积土中电流的3种流通路径示意(据Rhoadels et al.(1989))
Figure 9. Schematic diagram of three flow paths of current in residual soil(according to Rhoadels et al.(1989))
表 1 岩土物理力学性质参数
Table 1. Physical and mechanical properties of rock-soil
干密度
/g·cm-3天然密度
/g·cm-3塑限
/%液限
/%孔隙比 饱和渗透系数
/cm·s-11.33 1.61 33.6 54.3 1.04 7.2×10-5 表 2 岩兜滑坡土柱降雨试验方案
Table 2. Soil column rainfall test scheme
实验1 实验2 实验3 实验4 第1次降雨 雨强/mm·h-1 20 20 60 60 历时/h 3 3 3 3 雨停/d 1 1 1 无 第2次降雨 雨强/mm·h-1 20 20 20 20 历时/h 3 3 3 3 雨停/d 1 1 1 无 第3次降雨 雨强/mm·h-1 20 60 60 60 历时/h 9 3 3 3 雨停后监测时间/h 12 12 12 12 降雨历时/h 15 9 9 9 降雨量/mm 300 300 420 420 表 3 实验1初始值与传感器响应时间表
Table 3. Initial value and sensors response hysteresis
试验雨强 传感器编号 土体含水率 土体电阻率 初始值
/%响应时间
/min初始值
/Ω·m响应时间
/minDT1 31.25 30 242.08 30 DT2 36.44 40 200.48 40 20 mm·h-1 DT3 29.69 50 188.08 50 DT4 32.88 90 212.70 90 DT5 34.55 110 215.52 110 DT1 33.92 20 212.33 30 DT2 38.08 40 191.98 40 20 mm·h-1 DT3 30.72 50 156.81 50 DT4 33.99 80 199.36 80 DT5 35.72 90 196.60 90 DT1 34.03 20 207.26 20 DT2 38.12 30 198.48 30 20 mm·h-1 DT3 31.19 50 146.86 50 DT4 34.21 80 192.94 70 DT5 36.07 90 191.79 80 表 4 含水率-电阻率参数拟合结果表
Table 4. Water content-resistivity parameter fitting results
土体 拟合关系式 R2 偏差率 岩兜坡积土 ρ=1344.03ρwn-1.59θ-1.55 0.95 10.9% -
Archie G E. 1942. The electrical resistivity log as aid in determining some reservoir characteristics[J]. Transactions of AIME, 146 : 54-62. doi: 10.2118/942054-G Bian S Q, Yang Y P, Ma J H, et al. 2020. Two-dimensional imaging study of internal moisture in loess slope: A case study of the Luojiapo landslide in Heifangtai terrace[J]. Journal of Engineering Geology, 28(4): 840-851. doi: 10.13544/j.cnki.jeg.2019-345 Chambers J E, Gunn D A, Wilkinson P B, et al., 2014.4D electrical resistivity tomography monitoring of soil moisture dynamics in an operational railway embankment[J]. Near Surface Geophysics, 12(1): 61-72. doi: 10.3997/1873-0604.2013002 Crawford M M, Bryson L S, Woolery E W, et al. 2019. Long-term landslide monitoring using soil-water relationships and electrical data to estimate suction stress[J]. Engineering Geology, 251 : 146-157. doi: 10.1016/j.enggeo.2019.02.015 Dorofki M, Elshafie A H, Jaafar O, et al. 2014. A GIS-ANN-based ap-proach for enhancing the effect of slope in the modified green-ampt model[J]. Water Resources Management, 28(2): 391-406. doi: 10.1007/s11269-013-0489-7 Gance J, Malet R, Supper P, et al. 2016. Permanent electrical resistivity measurements for monitoring water circulation in clayey landslides[J]. Journal of Applied Geophysics, 126 : 98-115. doi: 10.1016/j.jappgeo.2016.01.011 Green W H, Ampt G A. 1911. Studies on soil physics Ⅰ. The flow of air and water through soils[J]. International Journal of Nonlinear Sciences & Numerical Simulation, 4(7-8): 1-24. doi: 10.1515/ijnsns-2015-0060 Guertault L, Fox G A. 2020. Performance of preferential flow models in predicting infiltration through a remolded soil with artificial macropores[J]. Vadose Zone Journal, 19(1): 1002-1014. doi: 10.1002/vzj2.20055 Guo X J, Jia Y G, Huang X Y, et al. 2004. Application of Multi-Electrodes electrical method to detection of slide-face position[J]. Chinese Journal of Rock Mechanics and Engineering, 23(10): 1662-1669. https://oversea.cnki.net/kcms/detail/detail.aspx?dbcode=CJFD&dbname=CJFD2004&filename=YSLX200410014 Jian W B, Huang C H, Luo Y H, et al. 2020. Experimental study on wetting front migration induced by rainfall infiltration in unsaturated eluvial and residual soil[J]. Rock and Soil Mechanics, 41(4): 1123-1133. doi: 10.16285/j.rsm.2019.0491 Jian W B, Xu Q, Tong L Y. 2013. Rainfall infiltration model of Huangtupo landslide in Three Gorges Reservoir area[J]. Rock and Soil Mechanics, 34(12): 3527-3533, 3548. http://ytlx.whrsm.ac.cn/EN/Y2013/V34/I12/3527 Keller G V, Frischknecht F C. 1966. Electrical methods in geophysical prospecting[M]. New York: Pergamom Press. Lan H X, Wu F Q, Zhou C H, et al. 2003. Spatial analysis and prediction of rainfall induced landslide risk supported by GIS[J]. Chinese Science Bulletin, 48(5): 507-512. doi: 10.1360/csb2003-48-5-507 Langhans C, Govers G, Diels J. 2013. Development and parameterization of an infiltration model accounting for water depth and rainfall inten-sity[J]. Hydrological Processes, 27(25): 3777-3790. doi: 10.1002/hyp.9491 Lu S J, Wang Y, Wen M Z. 2010. Research on geological disasters caused by monsoon rainstorm and typhoon rainstorm in Fujian province[J]. Geology of Fujian, 29(S1): 77-86. Montoya J D, García E F, Vega C A. 2017. One-dimensional experimental study of rainfall infiltration into unsaturated soil[J]. Revista Facultad De Ingenieria, 2017(82): 74-81. Ning L, Jonathan W G. 2014. Slope hydrology and stability[M]. Jian W X, Wang J G, Hou L, translation. Beijing: Higher Education Press. Philip J R. 1957. The theory of infiltration: 1. The infiltration equation and its solution[J]. Soil Science, 83(5): 345-357. doi: 10.1097/00010694-195705000-00002 Rhoades J D, Manteghi N A, Shouse P J, et al. 1989. Soil electrical conductivity and soil salinity: New formulations and calibrations[J]. Soil Science Society of America Journal, 53(2): 433-439. doi: 10.2136/sssaj1989.03615995005300020020x Shen J, Dong Y S, Jian W B, et al. 2020. Study on evolution process of landslides triggered by typhoon rainstorm[J]. Journal of Engineering Geology, 28(6): 1290-1299. doi: 10.13544/j.cnki.jeg.2019-540 Sun P, Wang G, Li R J, et al. 2019. Study on field test of loess slope under the artificial rainfall condition[J]. Journal of Engineering Geology, 27(2): 466-476. Wang Q J, Lai J B, Li Y. 2002. Comparison of Green-Ampt model with Philip Infiltration model[J]. Transactions of the Chinese Society of Agricultural Engineering, 18(2): 13-16. https://www.sciencedirect.com/science/article/pii/S1110492916300728 Waxman M H. 1968. Electrical conductivities in oil-bearing shaly sands[J]. Society of Petroleum Engineers Journal, 8(2): 107-122. doi: 10.2118/1863-A Zha F S, Liu S Y, Du Y J, et al. 2007. The electrical resistivity characteristics of unsaturated clayey soil[J]. Rock and Soil Mechanics, 28(8): 1671-1676. https://www.researchgate.net/publication/286987671_The_electrical_resistivity_characteristics_of_unsaturated_clayey_Soil Zha F S, Liu S Y, Du Y J, et al. 2010. Prediction of matric suction of unsaturated soil based on electrical resistivity[J]. Rock and soil Mechanics, 31(3): 1003-1008. doi: 10.1029/2008WR007309 Zha F S, Liu S Y, Du Y J. 2006a. Current status on use of electrical resisitivity method for ground improvement[J]. Journal of Engineering Geology, 14(5): 637-643. https://www.semanticscholar.org/paper/CURRENT-STATUS-ON-USE-OF-ELECTRICAL-RESISTIVITY-FOR-Yanjun/f03a1e40079ec8a1250f598fad7ca63265415371 Zha F S, Liu S Y. 2006b. Discussion on resistivity theory of soil and its application[J]. Geotechnical Investigation & Surveying, 5(7): 10-15, 44. https://www.sciencedirect.com/science/article/pii/0039602892912343 Zhang T L, Zhou A G, Shi B, et al. 2016. Physical experiment research on landslide deformation characteristics under the condition of the typhoon heavy rain[J]. Hydrogeology & Engineering Geology, 43(6): 127-132. https://www.swdzgcdz.com/en/article/id/20160620 Zhuo W S. 2020. Influence on groundwater seepage system and stability of landslide under rainfall in Yaoshan village, Anxi county[J]. Journal of Engineering Geology, 28(6): 1311-1318. Ning L, Jonathan W G. 2014. 斜坡水文与稳定[M]. 简文星, 王菁莪, 侯龙译. 北京: 高等教育出版社. 边世强, 杨云鹏, 马建花, 等. 2020. 黄土斜坡内部水分二维成像研究——以黑方台罗家坡滑坡为例[J]. 工程地质学报, 28(4): 840-851. doi: 10.13544/j.cnki.jeg.2019-345 查甫生, 刘松玉, 杜延军, 等. 2007. 非饱和黏性土的电阻率特性及其试验研究[J]. 岩土力学, 28(8): 1671-1676. doi: 10.3969/j.issn.1000-7598.2007.08.026 查甫生, 刘松玉, 杜延军, 等. 2010. 基于电阻率的非饱和土基质吸力预测[J]. 岩土力学, 31(3): 1003-1008. doi: 10.3969/j.issn.1000-7598.2010.03.058 查甫生, 刘松玉, 杜延军. 2006a. 电阻率法在地基处理工程中的应用探讨[J]. 工程地质学报, 14(5): 637-643. http://www.gcdz.org/article/id/9019 查甫生, 刘松玉. 2006b. 土的电阻率理论及其应用探讨[J]. 工程勘察, 5(7): 10-15, 44. https://www.cnki.com.cn/Article/CJFDTOTAL-GCKC200605002.htm 郭秀军, 贾永刚, 黄潇雨, 等. 2004. 利用高密度电阻率法确定滑坡面研究[J]. 岩石力学与工程学报, 23(10): 1662-1669. doi: 10.3321/j.issn:1000-6915.2004.10.014 简文彬, 黄聪惠, 罗阳华, 等. 2020. 降雨入渗下非饱和坡残积土湿润锋运移试验研究[J]. 岩土力学, 41(4): 1123-1133. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX202004002.htm 简文星, 许强, 童龙云. 2013. 三峡库区黄土坡滑坡降雨入渗模型研究[J]. 岩土力学, 34(12): 3527-3533, 3548. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201312028.htm 兰恒星, 伍法权, 周成虎, 等. 2003. GIS支持下的降雨型滑坡危险性空间分析预测[J]. 科学通报, 48(5): 507-512. doi: 10.3321/j.issn:0023-074X.2003.05.021 鹿世瑾, 王岩, 文明章. 2010. 福建雨季暴雨及台风暴雨诱发地质灾害的研究[J]. 福建地质, 29(S1): 77-86. https://www.cnki.com.cn/Article/CJFDTOTAL-FJDZ2010S1016.htm 沈佳, 董岩松, 简文彬, 等. 2020. 台风暴雨型土质滑坡演化过程研究[J]. 工程地质学报, 28(6): 1290-1299. doi: 10.13544/j.cnki.jeg.2019-540 孙萍, 王刚, 李荣建, 等. 2019. 降雨条件下黄土边坡现场试验研究[J]. 工程地质学报, 27(2): 466-476. doi: 10.13544/j.cnki.jeg.2018-031 王全九, 来剑斌, 李毅. 2002. Green-Ampt模型与Philip入渗模型的对比分析[J]. 农业工程学报, 18(2): 13-16. doi: 10.3321/j.issn:1002-6819.2002.02.004 张泰丽, 周爱国, 施斌, 等. 2016. 台风暴雨条件下滑坡变形特征物理试验研究[J]. 水文地质工程地质, 43(6): 127-132. https://www.cnki.com.cn/Article/CJFDTOTAL-SWDG201606021.htm 卓万生. 2020. 雨强对安溪县尧山村滑坡地下水渗流系统及稳定性的影响研究[J]. 工程地质学报, 28 (6): 1311-1318. doi: 10.13544/j.cnki.jeg.2020-150 -