入渗诱发黄土滑坡的力学机制  

Mechanism of infiltration-induced loess landslides

作　　者：周跃峰[1,2] 谭国焕[2] 甄伟文[2] 许领[3] 

机构地区：[1]长江科学院水利部岩土力学与工程重点实验室,武汉430010 [2]香港大学土木工程系 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《岩土力学》2013年第11期3173-3179,3186,共8页Rock and Soil Mechanics

基　　金：香港研究资助局资助项目(No.HKU7140/08E)

摘　　要：在农田水利建设蓬勃发展的同时,灌溉入渗在黄土塬边诱发了严重的滑坡灾害。作为黄土滑坡的典型区域,甘肃黑方台地区近年来受到了密切关注。为了研究入渗条件下黄土边坡的变形破坏机制,在黑方台典型滑坡后壁削取原状土样,开展了3组不同应力路径的三轴试验以模拟边坡的失稳过程。通过开展偏压固结不排水(ACU)试验和饱和恒载(SDL)增孔压试验研究了饱和黄土启动和变形破坏过程;通过开展非饱和恒载(UDL)增湿试验,研究了非饱和黄土启动和变形破坏过程。在此基础上,从应力路径和黄土的微观结构角度阐述了入渗诱发黄土滑坡的力学机制。此外,利用试验结果分析了黄土的典型物理力学特性,结果表明:在埋深应力范围内,该黄土的饱和临界状态线可简化为单一的直线;该黄土的状态边界线可近似为其临界状态线;由UDL试验预测的土-水特征曲线受应力状态影响,较高的应力水平对应较低含水率。With the great development of agricultural hydraulic engineering in China, irrigation induces serious landslide disasters at the edge of loess plateaus. As a typical region of loess landslides induced by agricultural irrigation, the Heifangtai plateau in Gansu province has been paid closed attentions in recent years. To investigate the deforming and failure mechanism of loess slope due to infiltration, undisturbed specimens are obtained from the backwall of a typical landslide in Heifangtai and are used to conduct three series of stress-path triaxial tests to simulate the process of slope failures. Through conducting anisotropically consolidated undrained （ACU） tests and saturated dead-load （SDL） tests with increased pore-water pressure, the initiation and failure processes of saturated loess are investigated. Through conducting unsaturated dead-load wetting （UDL） tests, the initiation and failure processes of unsaturated loess are investigated. Based on above results, the mechanism of infiltration-induced loess landslide is elaborated from the aspects of stress paths and microscopic structure of loess. Besides, the typical physico-mechanical properties of loess are analyzed. The results show that the saturated loess has a unique critical state line which reflects the major stress level corresponding to the thickness of the loess; the state boundary line of the loess can be approximated by its critical state line; the soil-water characteristic curves （SWCCs） obtained from the UDL tests are affected by the stress state, showing lower water content at higher stress level.

关 键 词：滑坡 黄土 非饱和土 应力路径试验 临界状态 土一水特征曲线 

分 类 号：TU444[建筑科学—岩土工程]