Dual-channel seepage model for tunnels with fissured soil under rainfall infiltration
-
摘要: 通过含单一裂隙土层局部渗流性态分析中得到的现象和结果,提出双通道渗流模型理论。基于阶跃函数推导了降雨诱发渗流的边界条件及其转换公式,以既有文献中的降雨入渗模型为基础,讨论了阶跃函数过渡区长度的设定,结果发现过渡区长度为4或8个单位时,计算结果较为准确。应用上述结果,通过COMSOL Multiphysics多物理场耦合方法模拟了双通道渗流效应,并探究降雨入渗情况下含裂隙土体的隧道围岩变形特征。同时根据可能影响隧道降雨入渗变形特征的因素包括裂隙位置、降雨强度、裂隙宽度进行多因素影响性分析。结果表明:随着降雨时间的增长,近裂隙一侧隧道拱顶沉降和上部水平位移值明显高于远裂隙侧;裂隙宽度越大,降雨入渗扩展越快,隧道产生的位移越大。对比2 mm裂隙宽度的拱顶沉降和上部水平位移,隧道上方存在8 mm宽度裂隙时,拱顶沉降最大值达328 mm,增幅达6.5%,上部水平位移最大值为26 mm,增幅达44%;降雨强度则对隧道围岩的影响较小。Abstract: The theory of a dual-channel seepage model is proposed based on the phenomena and results obtained from the analysis of local seepage behavior in soil layers with a single fissure. By using the step function, the boundary conditions and transformation formula for rainfall-induced seepage are derived. Based on the existing rainfall infiltration models in literatures, the setting of the transition zone length for the step function is discussed. It is found that the calculated results are more accurate when the transition zone length is 4 or 8 units. Applying the above results, the dual-channel seepage effects are simulated using the COMSOL Multiphysics, and the deformation characteristics of the surrounding rock of tunnel with fractured soil under rainfall infiltration are explored. At the same time, a multi-factor impact analysis is conducted based on the factors that may affect the deformation characteristics of rainfall infiltration of the tunnel, including fissure location, rainfall intensity and fissure width. The results show that with the increase of rainfall time, the settlements of the arch and upper horizontal displacement of the tunnel at the side near the fissure are significantly higher than those at side the far from the fissure. The larger the fissure width, the faster the rainfall infiltration and expansion, and the greater the displacement generated by the tunnel. Comparing the settlement of the arch crown with a fissure width of 2 mm and the upper horizontal displacement, when there is a fissure width of 8 mm above the tunnel, the maximum settlement of the arch crown reaches 328 mm, an increase of 6.5%, and the maximum horizontal displacement of the upper part is 26 mm, an increase of 44%. The intensity of rainfall has a relatively small impact on the surrounding rock of the tunnel.
-
-
表 1 各土层物理力学参数
Table 1 Physical and mechanical parameters of soil layers
土层 密度/(kg∙m-3) 含水率/% 孔隙率 弹性模量/MPa 泊松比 黏聚力/kPa 摩擦角/(°) 饱和渗透系数/(m∙s-1) 砂质土层 1380 17.9 0.412 18 0.3 21 27 2.1e-5 黏性土层 1500 16.7 0.385 25 0.3 25 30 1.3e-5 表 2 各区域非饱和水力参数
Table 2 Unsaturated hydraulic parameters of various regions
区域 模型 α/m-1 n l θr 基质 VG 2.0 1.5 0.5 0.04 裂隙 BC 2.68 0.131 0.5 0.04 表 3 模型参数
Table 3 Model parameters
Ks/(m·d-1) v0/(m·d-1) θs/% θr/% α/m-1 n H0/m 1.39×10-5 4Ks 40 4 2.5 2.1 -0.4 表 4 多工况分析中各参数变化值
Table 4 Change of various parameters in multi-operating condition analysis
工况 参数变化 1 裂隙位置X=30 m,裂隙宽度u=0.002 m,降雨强度V0=0.1 m·d-1 2 裂隙位置X=25 m,裂隙宽度u=0.002 m,降雨强度V0=0.1 m·d-1 3 裂隙位置X=20 m,裂隙宽度u=0.008 m,降雨强度V0=0.1 m·d-1 4 裂隙位置X=30 m,裂隙宽度u=0.008 m,降雨强度V0=0.1 m·d-1 5 裂隙位置X=25 m,裂隙宽度u=0.008 m,降雨强度V0=0.1 m·d-1 -
[1] 蔡国庆, 韩博文, 韦靖威, 等. 复杂水-力路径下非饱和砂质黄土增湿变形特性[J]. 岩石力学与工程学报, 2022, 41(增刊1): 3073-3080. CAI Guoqing, HAN Bowen, WEI Jingwei, et al. Wetting deformation characteristics of unsaturated sandy loess under complex hydro-mechanical paths[J]. Chinese Journal of Rock Mechanics and Engineering, 2022, 41(S1): 3073-3080. (in Chinese)
[2] 李锦辉, 郭凌波, 张利民. 考虑裂隙动态变化时裂隙土土水特征曲线的预测方法研究[J]. 岩石力学与工程学报, 2013, 32(6): 1288-1296. LI Jinhui, GUO Lingbo, ZHANG Limin. Prediction of swcc for unsaturated cracked soil considering development process of cracks[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(6): 1288-1296. (in Chinese)
[3] VAN GENUCHTEN M T. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J]. Soil Science Society of America Journal, 1980, 44(5): 892-898. doi: 10.2136/sssaj1980.03615995004400050002x
[4] 殷宗泽, 徐彬. 反映裂隙影响的膨胀土边坡稳定性分析[J]. 岩土工程学报, 2011, 33(3): 454-459. http://cge.nhri.cn/article/id/13962 YIN Zongze, XU Bin. Slope stability of expansive soil under fissure influence[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(3): 454-459. (in Chinese) http://cge.nhri.cn/article/id/13962
[5] 邵生俊, 杨春鸣, 焦阳阳, 等. 湿陷性黄土隧道的工程性质分析[J]. 岩土工程学报, 2013, 35(9): 1580-1590. http://cge.nhri.cn/article/id/15269 SHAO Shengjun, YANG Chunming, JIAO Yangyang, et al. Engineering properties of collapsible loess tunnel[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(9): 1580-1590. (in Chinese) http://cge.nhri.cn/article/id/15269
[6] 赖金星, 樊浩博, 来弘鹏, 等. 软弱黄土隧道变形规律现场测试与分析[J]. 岩土力学, 2015, 36(7): 2003-2012, 2020. LAI Jinxing, FAN Haobo, LAI Hongpeng, et al. In-situ monitoring and analysis of tunnel deformation law in weak loess[J]. Rock and Soil Mechanics, 2015, 36(7): 2003-2012, 2020. (in Chinese)
[7] FRENELUS W, PENG H, ZHANG J Y. Seepage actions and their consequences on the support scheme of deep-buried tunnels constructed in soft rock strata[J]. Infrastructures, 2024, 9(1): 13. doi: 10.3390/infrastructures9010013
[8] CHEN L L, WANG Z F, WANG Y Q. Failure analysis and treatments of tunnel entrance collapse due to sustained rainfall: a case study[J]. Water, 2022, 14(16): 2486. doi: 10.3390/w14162486
[9] SI J L, LIU S P, ZHANG H J, et al. Failure investigation and treatments of tunnel entrance collapse in weak diatomaceous soil induced by heavy rainfall through coupling surface and groundwater flows[J]. Engineering Failure Analysis, 2023, 150: 107337. doi: 10.1016/j.engfailanal.2023.107337
[10] 韩同春, 何露, 林博文, 等. 一种裂隙土的双重入渗模型及对边坡稳定的影响[J]. 华南理工大学学报(自然科学版), 2019, 47(5): 123-129, 138. HAN Tongchun, HE Lu, LIN Bowen, et al. Double infiltration model of fractured soil and its influence on slope stability[J]. Journal of South China University of Technology (Natural Science Edition), 2019, 47(5): 123-129, 138. (in Chinese)
[11] 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 Wuramu, ZHANG Zizhao, ZHANG Yanyang, 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)
[12] 曾铃, 史振宁, 付宏渊, 等. 降雨入渗对边坡暂态饱和区分布特征的影响[J]. 中国公路学报, 2017, 30(1): 25-34. ZENG Ling, SHI Zhenning, FU Hongyuan, et al. Influence of rainfall infiltration on distribution characteristics of slope transient saturated zone[J]. China Journal of Highway and Transport, 2017, 30(1): 25-34. (in Chinese)
[13] 邱军领, 秦祎文, 赖金星, 等. 突发高压渗流作用下黄土地铁隧道水压阶跃效应分析[J]. 岩土工程学报, 2023, 45(4): 758-767. doi: 10.11779/CJGE20220062 QIU Junling, QIN Yiwen, LAI Jinxing, et al. Step effects of hydraulic pressure of metro tunnels in loess under sudden high-pressure seepage[J]. Chinese Journal of Geotechnical Engineering, 2023, 45(4): 758-767. (in Chinese) doi: 10.11779/CJGE20220062
[14] 张万志, 徐帮树, 曾仲毅, 等. 降雨入渗下膨胀性黄土隧道围岩破坏演化[J]. 东南大学学报(自然科学版), 2018, 48(4): 736-744. ZHANG Wanzhi, XU Bangshu, ZENG Zhongyi, et al. Research on failure evolution process of surrounding rock of swelling loess tunnel under rainfall infiltration[J]. Journal of Southeast University (Natural Science Edition), 2018, 48(4): 736-744. (in Chinese)
[15] 高阳, 孙浩凯, 刘德军, 等. 强降雨影响下破碎复理岩地层隧道洞口段失稳机理[J]. 中南大学学报(自然科学版), 2019, 50(9): 2295-2303. GAO Yang, SUN Haokai, LIU Dejun, et al. Collapse mechanism of tunnel portal sectionin broken flysch under influence of heavy rainfall[J]. Journal of Central South University (Science and Technology), 2019, 50(9): 2295-2303. (in Chinese)
[16] 谢强, 陈昱成, 傅翔, 等. 非饱和瞬态渗流的DDA流固耦合模型研究[J]. 岩土工程学报, 2024, 46(2): 299-306. doi: 10.11779/CJGE20221026 XIE Qiang, CHEN Yucheng, FU Xiang, et al. Fluid-solid coupling model for discontinuous deformation analysis of unsaturated transient seepage[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(2): 299-306. (in Chinese) doi: 10.11779/CJGE20221026
[17] 黄阜, 纪恒博, 王子钦, 等. 考虑土体非均质性和孔隙水压力耦合作用的地下连续墙槽壁稳定性研究[J]. 岩土工程学报, 2024, 46(3): 539-548. doi: 10.11779/CJGE20221401 HUANG Fu, JI Hengbo, WANG Ziqin, et al. Stability of slurry trench walls considering coupling effects of soil heterogeneity and pore water pressure[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(3): 539-548. (in Chinese) doi: 10.11779/CJGE20221401
[18] SHAO W, BOGAARD T, BAKKER M. How to use COMSOL multiphysics for coupled dual-permeability hydrological and slope stability modeling[J]. Procedia Earth and Planetary Science, 2014, 9: 83-90. doi: 10.1016/j.proeps.2014.06.018
[19] 马慧. COMSOL Multiphysics基本操作指南和常见问题解答[M]. 人民交通出版社, 2009. MA Hui. COMSOL Multiphysics Basic Operation Guide and Frequently Asked Questions[M]. Beijing: China Communications Press, 2009. (in Chinese)
[20] 年庚乾, 陈忠辉, 张凌凡, 等. 边坡降雨入渗问题中两种边界条件的处理及应用[J]. 岩土力学, 2020, 41(12): 4105-4115. NIAN Gengqian, CHEN Zhonghui, ZHANG Lingfan, et al. Treatment of two boundary conditions for rainfall infiltration in slope and its application[J]. Rock and Soil Mechanics, 2020, 41(12): 4105-4115. (in Chinese)
[21] 侯晓萍, 樊恒辉. 基于COMSOL Multiphysics的非饱和裂隙土降雨入渗特性研究[J]. 岩土力学, 2022, 43(2): 563-572. HOU Xiaoping, FAN Henghui. Study on rainfall infiltration characteristics of unsaturated fractured soil based on COMSOL Multiphysics[J]. Rock and Soil Mechanics, 2022, 43(2): 563-572. (in Chinese)
-
其他相关附件