Unsaturated Seepage Characteristics of Slope under Rainfall Infiltration
-
摘要: 为了分析降雨入渗影响下非饱和土坡渗流特性，利用自制降雨模拟系统和实时监测系统，对降雨诱发非饱和土坡失稳过程进行全方位、多参量的实时监测，研究不同降雨条件下，不同坡度、不同压实度边坡坡体不同位置雨水入渗率和湿润峰的实变规律.结果表明：降雨入渗条件下，陡坡和高压实度土体不利于雨水入渗，而缓坡和低密实度土体入渗率变化快；实际土体吸力和含水量实时变化规律不同步，提出试验湿润峰概念，含水率（吸力）湿润峰点可按含水率（吸力）实时曲线的过渡区和雨后残余含水率（吸力）的线性交叉点确定；考虑单向吸湿或脱湿路径下土体含水率和吸力具有唯一对应关系，含水率湿润峰点与吸力湿润峰点的绝对值时差即为形成湿润峰所需时间；对比湿润峰实测值与Lumb半经验值散点分布规律，基于Lumb湿润峰深度计算公式提出非线性修正表达式.Abstract: In order to analyze unsaturated seepage characteristics of slope under rainfall infiltration, a rainfall simulation system and real-time monitoring system were employed for conducting model tests to simulate the rainfall-induced unsaturated soil slope failure process in this study. The real-time response of infiltration rate and wetting front of soil slope with different slope angles, different compaction degrees and different locations under different rainfall conditions were recorded and analyzed. Results show that steep slope and high compaction degree soil are not conducive to rainfall infiltration, while gentle slope and low compaction degree soil have a quick change of infiltration rate; the concept of test wetting front is proposed due to the real-time law of actual soil suction and water content under rainfall conditions are not synchronized, and the water content (suction) wetting front point can be determined by a linear intersection of water content (suction) real-time curve transition zone and residual water content (suction) after rainfall; considering water content and soil suction have the only corresponding relationship under unidirectional wetting and drying path, the time needed for wetting front formation can be seen as the absolute value of time differences between water content and suction wetting front point. Based on the Lumb formula of wetting front depth, the nonlinear correction expression is proposed subsequently by comparing the scatter distribution of wetting front measured and semi-empirical values.
-
图 1 试验装置及模型边坡示意图
a.水分计; b.张力计局部连接; c.数据采集传输系统; d.无限边坡模型; e.全边坡模型
Fig. 1. Test equipment and schematic diagram of slope model
图 3 部分模型边坡监测件埋设示意图
a.34°全边坡模型立面图; b.34°全边坡模型平面图; c.17°无限边坡模型立面图; d.17°无限边坡模型平面图
Fig. 3. Schematic diagram of slope monitoring embedding
图 4 不同降雨条件下边坡土体吸力和含水率实时数据
a.试验1第一次降雨过程；b.试验1第二次降雨过程; c.试验5第一次降雨过程; d.试验5第二次降雨过程.图 4中HS/XL-A-B-1/2含义为：HS指含水率；XL指吸力；A代表监测点号；B表示测点埋深；1/2表示第一次/第二次降雨
Fig. 4. Soil suction and water content real-time data of model slope under different rainfall conditions
图 5 降雨条件下各模型边坡所用土体的SWCC曲线
a.试验1，土体含水率-吸力曲线；b.试验5，土体含水率-吸力曲线
Fig. 5. Soil Water Characteristic Curve of model slope under different rainfall conditions
图 7 积水入渗含水率变化剖面图
a.某时刻含水率剖面; b.积水入渗含水率随时间变化剖面；雷志栋等(1988)
Fig. 7. Water content change section of pond water infiltration
图 9 不同时刻土体湿润峰实测值与半经验值关系
a.试验1；b.试验5
Fig. 9. Relationship between the measured and semi-empirical values of soil wetting front under different time
图 10 土体湿润峰实测值与半经验值的关系图
Fig. 10. Relationship between the measured and semi-empirical values of soil wetting front
表 1 残积土颗分试验结果
Table 1. Residual soil size distribution testing results
残积 颗粒组成(%) 土层 >2 2~0.5 0.5~0.25 0.25~0.075 < 0.075 粘性土 1.0 5.0 6.8 25.8 61.4 
下载: 导出CSV
表 2 模型试验方案
Table 2. Scheme of experiments
试验 模型 压实度 坡角 数量 监测件
埋深(cm)水分计 张力计 1 全边坡 84% 45° 7 7 20、30、40、70 2 全边坡 84% 34° 7 7 30、50、70 3 无限边坡 84% 26° 3 3 20、32 4 无限边坡 77% 26° 3 3 5 无限边坡 77% 17° 4 4
下载: 导出CSV
表 3 模型边坡类型及计算参数
Table 3. Model slope types and calculation parameters
试验 1 2 3 4 5 类别 全边坡 全边坡 无限边坡 无限边坡 无限边坡 干密度ρd(g·cm-3) 1.385 1.385 1.385 1.240 1.240 孔隙率n 0.441 0.441 0.441 0.488 0.488 饱和渗透系数ksat(m·s-1) 1.5×10-6 1.5×10-6 1.5×10-6 4.5×10-6 4.5×10-6
下载: 导出CSV
表 4 试验湿润峰时间点计算
Table 4. Calculation of test wetting front point-in-time
试验 监测点位置(m) 时刻(min) 试验 监测点位置(m) 时刻(min) 第一次降雨 第二次降雨 第一次降雨 第二次降雨 含水率点 吸力点 含水率点 吸力点 含水率点 吸力点 含水率点 吸力点 1 0.20 240 216 108 132 3 0.20 276 240 132 156 1 0.30 312 300 144 168 3 0.32 360 420 180 192 1 0.40 420 390 192 228 4 0.20 252 228 120 144 1 0.70 660 600 240 288 4 0.32 336 312 156 180 2 0.30 300 276 144 132 5 0.20 204 228 96 - 2 0.50 420 480 192 216 5 0.32 312 276 132 108 2 0.70 540 600 288 276
下载: 导出CSV
表 5 模型边坡土体湿润峰实测值与半经验值成果
Table 5. Outcome table of the measured and semi-empirical values of model slope soil wetting front
试验编号 实测值d(m) 半经验值h(m) 试验编号 实测值d(m) 半经验值h(m) 第一次降雨 第二次降雨 第一次降雨 第二次降雨 1 0.2 0.238 0.278 3 0.2 0.280 0.386 1 0.3 0.319 0.361 3 0.32 0.424 0.532 1 0.4 0.423 0.486 4 0.2 0.566 1.238 1 0.7 0.658 0.611 4 0.32 0.764 1.650 2 0.3 0.316 0.303 5 0.2 0.365 1.048 2 0.5 0.494 0.448 5 0.32 0.497 1.348 2 0.7 0.626 0.619 注：现场观测点埋深10 cm、35 cm，半经验值16.7 cm、40.9 cm.
下载: 导出CSV
-
Bodman, G.B., Colman, E.A., 1944.Moisture and Energy Conditions during Downward Entry of Water into Soils 1.Soil Science Society of America Journal, 8(C):116.https://doi.org/10.2136/sssaj1944.036159950008000c0021x doi: 10.2136/sssaj1944.036159950008000C0021x Chen, L., Young, M.H., 2006.Green-Ampt Infiltration Model for Sloping Surfaces.Water Resources Research, 42(7):1-9. https://doi.org/10.1029/2005wr004468 Feng, H.J., Zhou, A.G., Yu, J.J., et al., 2016.A Comparative Study on Plum-Rain-Triggered Landslide Susceptibility Assessment Models in West Zhejiang Province.Earth Science, 41(3):403-415(in Chinese with English abstract). doi: 10.1186/s40677-017-0078-9 Gu, B.X., Liang, P.F., Peng, H.T., et al., 2010.Rainfall Simulation Experimental Study on Infiltration of Soil under Sand and Gravel Mulch.Chinese Agricultural Science Bulletin, 27(32):281-286(in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-ZNTB201132054.htm Han, T.C., Ma, S.G., Xu, R.Q., 2013.Research on Delayed Effect of Landslides Caused by Air Pressure under Heavy Rainfall.Rock and Soil Mechanics, 34(5):1360-1366 (in Chinese with English abstract). http://www.en.cnki.com.cn/Article_en/CJFDTOTAL-YTLX201305020.htm Huang, F.M., Yin, K.L., Zhang, G.R., et al., 2015.Landslide Groundwater Level Time Series Prediction Based on Phase Space Reconstruction and Wavelet Analysis-Support Vector Machine Optimized by PSO Algorithm.Earth Science, 40(7):1254-1265 (in Chinese with English abstract). Jian, W.X., Xu, Q., Tong, L.Y., 2013.Rainfall Infiltration Model of Huangtupo Landslides in Three Gorges Reservoir Area.Rock and Soil Mechanics, 34(12):3527-3533 (in Chinese with English abstract). Lei, Z.D., Yang, S.X., Xie, S.C., 1988.Soil Water Dynamics.Tsinghua University Press, Beijing, 77-78 (in Chinese). Li, A.G., Yue, Z.Q., Tham, L.G., et al., 2005.Field-Monitored Variations of Soil Moisture and Matric Suction in a Saprolite Slope.Canadian Geotechnical Journal, 42(1):13-26. https://doi.org/10.1139/t04-069 Lumb, P., 1962.Effect of Rain Storms on Slope Stability.Proceedings of the Symposium on Hong Kong Soils, Hong Kong, 73-87. Luo, X.Q., Ge, X.R., 2008.Theory and Application of Model Test on Landslide.China Water Power Press, Beijing, 112-115 (in Chinese). Mein, R.G., Larson, C.L., 1973.Modeling Infiltration during a Steady Rain.Water Resources Research, 9(2):384-394.https://doi.org/10.1029/wr009i002p00384 doi: 10.1029/WR009i002p00384 Muntohar, A.S., Liao, H.J., 2010.Rainfall Infiltration:Infinite Slope Model for Landslides Triggering by Rainstorm.Natural Hazards, 54(3):967-984. https://doi.org/10.1007/s11069-010-9518-5 Philip, J.R., 1955.Numerical Solution of Equations of the Diffusion Type with Diffusivity Concentration Dependent.Trans.Faraday Soc., 51:885-892.https://doi.org/10.1039/TF9555100885 doi: 10.1039/tf9555100885 Wang, J.X., Wang, E.Z, Wang, S.J., 2010.Potential Description of Rainfall Free Infiltration Phase.Journal of Tsinghua University (Science & Technology), 50(12):1920-1924 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-QHXB201012005.htm Ye, W.M., Tang, Y.Q., Cui, Y.J., 2005.Measurement of Soil Suction in Laboratory and Soil-Water Characteristics of Shanghai Soft Soil.Chinese Journal of Geotechnical Engineering, 27(3):347-349 (in Chinese). http://en.cnki.com.cn/Article_en/CJFDTOTAL-YTGC20050300L.htm Ye, W.M., Qian, L.X., Chen, B., et al., 2009.Laboratory Test on Unsaturated Hydraulic Conductivity of Densely Compacted Gaomiaozi Bentonite under Confined Conditions. Chinese Journal of Geotechnical Engineering, 31(1):105-108 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-YTGC200901023.htm Yu, M.L., Mei, H.B., Li, J.H., et al., 2016.Landslide Displacement Prediction Based on Varying Coefficient Regression Model in Three Gorges Reservoir Area.Earth Science, 41(9):1593-1602 (in Chinese with English abstract). 冯杭建, 周爱国, 俞剑君, 等, 2016.浙西梅雨滑坡易发性评价模型对比.地球科学, 41(3):403-415. http://www.earth-science.net/WebPage/Article.aspx?id=3259 谷博轩, 梁鹏锋, 彭红涛, 等, 2010.砂田降雨入渗过程的模拟实验研究.中国农学通报, 27(32):281-286. http://d.wanfangdata.com.cn/Periodical_zgnxtb201132054.aspx 韩同春, 马世国, 徐日庆, 2013.强降雨条件下气压对滑坡延时效应研究.岩土力学, 34(5):1360-1366. http://industry.wanfangdata.com.cn/dl/Detail/Periodical?id=Periodical_ytlx201305023 黄发明, 殷坤龙, 张桂荣, 等, 2015.基于相空间重构和小波分析-粒子群向量机的滑坡地下水位预测.地球科学, 40(7):1254-1265. http://www.earth-science.net/WebPage/Article.aspx?id=3113 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.岩土力学, 34(12):3527-3533. http://d.old.wanfangdata.com.cn/Periodical/ytlx201312028 雷志栋, 杨诗秀, 谢森传, 1988.土壤水动力学.北京:清华大学出版社, 77-78. 罗先启, 葛修润, 2008.滑坡模型试验理论及其应用.北京:中国水利水电出版社, 112-115. 王建新, 王恩志, 王思敬, 2010.降雨自由入渗阶段试验研究及其过程的水势描述.清华大学学报(自然科学版), 50(12):1920-1924. http://www.cqvip.com/QK/93884X/201012/36981012.html 叶为民, 唐益群, 崔玉军, 2005.室内吸力量测与上海软土土水特征.岩土工程学报, 27(3):347-349. http://www.oalib.com/paper/4370015 叶为民, 钱丽鑫, 陈宝, 等, 2009.侧限状态下高压实高庙子膨润土非饱和渗透性的试验研究.岩土工程学报, 31(1):105-108. http://manu31.magtech.com.cn/Jwk_ytgcxb/CN/abstract/abstract13113.shtml 喻孟良, 梅红波, 李冀骅, 等, 2016.基于变系数回归模型的三峡库区滑坡位移预测.地球科学, 41(9):1593-160. http://www.earth-science.net/WebPage/Article.aspx?id=3364 -
点击查看大图
计量
- 文章访问数: 4188
- HTML全文浏览量: 1968
- PDF下载量: 37
- 被引次数: 0
