非饱和地震滑坡堆积体降雨破坏水-力耦合行为试验  

Experiment on hydro-mechanical behavior of unsaturated gravelly soil slope

作　　者：杨宗佶[1] 蔡焕[1,2] 雷小芹 王礼勇[1,2] 丁朋朋 乔建平 YANG Zong-ji;CAI Huan;LEI Xiao-qin;WANG Li-yong;DING Peng-peng;QIAO Jian-ping(Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu,Sichuan 610041,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院水利部成都山地灾害与环境研究所,四川成都610041 [2]中国科学院大学,北京100049

出　　处：《岩土力学》2019年第5期1869-1880,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.41771021;No.41471012);中国科学院水利部成都山地灾害与环境研究所‘一三五’方向性项目(No.SDS-135-1701;No.SDS-135-1704)~~

摘　　要：降雨滑坡的水-力耦合过程和机制研究是开展准确预测预报的基础和前提。选取典型滑坡模型,采用足尺人工降雨模型试验模拟了典型砾石土滑坡堆积体破坏过程,并采用Brooks-Corey(BC)和Van Genuchten(VG)模型分别建立了降雨入渗吸湿过程的土-水特征曲线,再通过一维非饱和无限边坡稳定性分析模型对滑坡开展应力状态和稳定性分析,揭示了斜坡破坏过程是优先流和基质流的双渗流场共同作用的结果,而VG模型适用于吸湿条件下宽级配砾石土优先流的土-水特征曲线的重构;稳定性计算和试验过程的对比分析表明,试验中斜坡的变形破坏过程中观测到的含水率、基质吸力和地表倾斜角度的变化过程与计算的吸力应力、稳定系数的演进过程有显著的对应关系。通过试验还揭示了非饱和滑坡堆积体渗流潜蚀现象,定量分析了细颗粒迁移程度。基于物理模型试验,揭示了降雨激发条件下滑坡堆积体形成优先流作用的土-水特征曲线和变形破坏的水力耦合过程,可为地震滑坡堆积体非饱和失稳的预测预警提供参考和基础。A profound understanding of hydro-mechanical coupling process in rainfall-induced landslides and its formation mechanism are prerequisites for the accurate early warning. In this study, a typical landslide in Wenchuan earthquake region is selected for a series of full-scale artificial rainfall tests, to simulate failure progress on gravelly soil slope of landslide deposit. Two classical soil-water characteristic curve(SWCC) models, Brooks-Corey(BC) and Van Genuchten(VG) model, are used to establish the SWCC during rainfall infiltration. Then, the stress state and stability of slope are analyzed by one-dimensional variably saturated infinite slope model. The results reveal that the slope failure is the consequence of dual-permeability interaction between the preferential flow and the matrix flow. The VG model is capable of fitting SWCC of wide-graded gravelly soil during wetting process for preferential flow. Comparison between stability analysis and observation indicates that changes on volumetric water content,matric suction and surface inclination are consistent with calculated suction stress and safety factor. Finally, the seepage erosion in unsaturated slope is proved by the tests, and the migration of fine particles is statistically analyzed. Based on the physical model test,this study reveals the coupling process of soil-water characteristic curves and slope failure with the influence of preferential flow under rainfall conditions, which can provide reference and basis for the prediction and early warning of unsaturated slope instability.

关 键 词：非饱和 砾石土 浅层滑坡 足尺模型试验 水-力耦合 

分 类 号：TU411[建筑科学—岩土工程]