Numerical Analysis for Shallow Landslides of Expansive Soil Slopes Based on Three Fields Coupling
-
摘要: 为研究膨胀土边坡浅层坍滑的原因,利用有限差分软件FLAC2D,借鉴已有多场耦合数值计算思路,通过二相流与热模块模拟了降雨条件下坡体内的非饱和渗流过程及膨胀土的吸湿膨胀;并依据膨胀土饱和度与温度及热膨胀系数的转换关系,利用FISH软件编制了程序调用两模块的信息,实时模拟了土的吸湿膨胀效应,实现了考虑地下水位和渗透系数变化、强度衰减三因素下的膨胀土坡渗流场-位移场-应力场的三场耦合。并基于此,建立了考虑和未考虑膨胀变形的数值模型,分别模拟了降雨条件下计及和未计吸湿膨胀的边坡非饱和渗流过程及其稳定性,对比分析同降雨强度但不同历时、是否计及吸湿膨胀边坡的渗流场及稳定性的差异,揭示膨胀土吸湿膨胀是引起边坡浅层坍滑的重要原因;据此进一步研究不同降雨强度、降雨历时下膨胀土边坡的稳定性,同时对比分析边坡渗流场和应力场的变化及其分布规律,得到不同降雨条件对边坡浅层坍滑的影响。Abstract: To revealing the reasons for shallow landslides of expansive soil slopes, in reference to the existing calculation ways of multifield-coupling numerical analysis, the seepage processes from unsaturation to saturation in expansive soil slopes and hygroscopic expansion processes were simulated by the two-phase flow module and thermal module of the finite difference software FLAC2D;based on the transformation relations for saturation degrees, temperatures and thermal expansion coefficients of expansive soil and integrating and extracting the information from both of the modules simultaneously, the hygroscopic expansion effect of expansive soil was simulated in time;the three fields involving the seepage field, displacement field and stress field were coupled under consideration for the changes of groundwater levels and permeability coefficients and intensity attenuation. And then, the numerical model with or without expansive deformation was constructed. The seepage processes from unsaturation to saturation in slopes considered and not considered the hygroscopic expansion during rainfall and the stability of slopes were simulated individually;the difference of seepage fields and slopes stability between considering and not considering the hygroscopic expansion effect in the same rainfall intensities but different rainfall duration was contrasted and analyzed. The important reason caused shallow landslides of expansive soil slopes was revealed, it was hygroscopic expansion of expansive soil. Furthermore, the stability of expansive soil slopes under different rainfall intensities and durations was further studied, the variation and distribution of the seepage field and stress field in slopes were compared and analyzed at the same time, and the effects of different rainfall conditions on shallow landslides were obtained.
-
Key words:
- expansive soil slope /
- shallow landslide /
- rainfall /
- three field coupling /
- numerical analysis /
- swelling deformation
-
[1] 包承刚. 非饱和土的性状及膨胀土边坡稳定问题[J]. 岩土工程学报,2004,26(1):1-15. [2] 童超, 杨和平. 由膨胀土内比表面及孔径分布来评价其膨胀行为[J]. 中外公路, 2017, 37(1):209-215. [3] 张连杰. 降雨入渗条件下膨胀土边坡稳定性分析[D]. 北京:中国地质大学, 2016. [4] 肖杰, 杨和平, 李晗峰, 等. 膨胀土边坡浅层破坏稳定性分析[J]. 交通运输工程学报, 2014, 14(2):21-27. [5] 叶为民, 万敏, 陈宝, 等. 干湿循环条件下高压实膨润土的微观结构特征[J]. 岩土工程学报, 2011, 33(8):1173-1177. [6] 魏星, 王刚. 干湿循环作用下击实膨胀土胀缩变形模拟[J]. 岩土工程学报, 2014, 36(8):1423-1431. [7] 方瑾瑾, 杨小林, 冯以鑫, 等. 干湿循环后膨胀土力学特性的真三轴试验研究[J/OL]. 岩石力学与工程学报. https://doi.org/10.13722/j.cnki.jrme. 2020.0902. [8] LIU G, TOLL D G, KONG L, et al. Matric suction and volume characteristics of compacted clay soil under drying and wetting cycles[J]. Geotechnical Testing Journal, 2020, 43(2):464-479. [9] 徐锴, 耿之周, 李雄威. 脱湿速率对膨胀土堑坡稳定性的影响分析[J].岩土工程学报, 2017, 39(增刊1):131-134. [10] 杨和平, 程斌, 肖杰, 等. 土工格栅反包加筋支护膨胀土堑坡的工作机理[J]. 公路交通科技, 2015, 32(9):1-8. [11] 程展林, 龚壁卫. 膨胀土边坡[M]. 北京:科学出版社, 2015. [12] 郑俊杰,郭震山,崔岚,等. 考虑非饱和渗流与增湿膨胀下的膨胀土隧道稳定性分析[J]. 岩土力学, 2017, 38(11):3271-3277. [13] 丁金华,陈仁朋,童军等. 基于多场耦合数值分析的膨胀土边坡浅层膨胀变形破坏机制研究[J]. 岩土力学,2015(增刊1):159-168. [14] 张良以, 陈铁林, 张顶立. 降雨诱发膨胀土边坡渐进破坏研究[J]. 岩土工程学报, 2019, 41(1):70-77. [15] QI S, VANAPALLI S K. Hydro-mechanical coupling effect on surficial layer stability of unsaturated expansive soil slopes[J]. Computers & Geotechnics, 2015, 70:68-82. [16] 石振明, 沈丹祎, 彭铭, 等.考虑多层非饱和土降雨入渗的边坡稳定性分析[J].水利学报, 2016, 47(8):977-985. [17] 肖杰, 杨和平, 林京松, 等. 模拟干湿循环及含低围压条件的膨胀土三轴试验[J].中国公路学报, 2019, 32(1):21-28. [18] Itasca Consulting Group Inc. Fast lagrangian analysis of continua in two dimensions, user's manual[M]. Minnesota:Itasca Consulting Group Inc., 2011. [19] 贺鹏. 降雨条件下膨胀土堑坡浅层滑坍及加筋处治效果数值模拟[D]. 长沙:长沙理工大学, 2014.
点击查看大图
计量
- 文章访问数: 95
- HTML全文浏览量: 24
- PDF下载量: 5
- 被引次数: 0