梯田型黄土滑坡隐患非饱和土抗剪强度特性  

Shear strength characteristics of unsaturated soil at terrace loess potential landslide

作　　者：毛正君[1,2,3] 王木楠 张瑾鸽 赵煜鑫 仲佳鑫 MAO Zhengjun;WANG Munan;ZHANG Jin’ge;ZHAO Yuxin;ZHONG Jiaxin(College of Geology and Environment,Xi’an University of Science and Technology,Xi’an 710054,China;Geological Research Institute for Coal Green Mining,Xi’an University of Science and Technology,Xi’an 710054,China;Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation,Xi’an 710054,China;Key Laboratory of Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University,Beijing 100044,China;Ningxia Institute of Survey and Monitoring of Land and Resources,Yinchuan 750002,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054 [2]西安科技大学煤炭绿色开采地质研究院,陕西西安710054 [3]陕西省煤炭绿色开发地质保障重点实验室,陕西西安710054 [4]北京交通大学城市地下工程教育部重点实验室,北京100044 [5]宁夏国土资源调查监测院,宁夏银川750002

出　　处：《西安科技大学学报》2025年第2期328-339,共12页Journal of Xi’an University of Science and Technology

基　　金：陕西省重点研发计划项目(2020SF-379);宁夏回族自治区重点研发计划项目(2022BEG03059,2023BEG02072)。

摘　　要：为研究梯田型黄土滑坡隐患非饱和土抗剪强度特性,以宁夏回族自治区固原市彭阳县挂马沟梯田型黄土滑坡隐患为研究对象,在发生局部变形破坏区及未发生局部变形破坏梯田的对应部位取土样,通过常规直剪试验方法得到不同含水率下4种土样的剪应力与剪切位移关系,分析脆性指数、峰值强度和抗剪强度指标与含水率的关系,利用滤纸法结合FX模型和VG模型拟合出4种土样的土水特征曲线,提出总应力条件和广吸力范围的非饱和土抗剪强度公式。结果表明:4种土样的剪应力与剪切位移关系曲线随着含水率的降低呈增加趋势,接近饱和含水率的试样关系曲线为硬化型,随着含水率的降低逐步过渡到软化型,含水率低于14%呈现断崖式下跌;对于低含水率试样的脆性破坏现象提出了改进脆性指数,对4种土样以脆性指数0.3、含水率14%作为基准划分塑性破坏区和脆性破坏区;土样的峰值强度随着含水率的减小可以分为稳定增长区和波动增长区2个阶段,以14%含水率为界限,随着含水率的上升,抗剪强度指标黏聚力和内摩擦角呈减小趋势;采用广吸力范围改进的非饱和土强度公式,对试验数据进行拟合,拟合度均达到0.844以上。研究成果为梯田型黄土滑坡隐患监测预警及其防治提供理论依据和技术支撑。In order to explore the shear strength characteristics of unsaturated soil in dry farming terraces on the Loess Plateau,the potential Guamagou terrace loess landslide in Pengyang County,Guyuan City was taken as the research object,and the conventional direct shear test method was used to get the shear stress and shear displacement relationship curves of four soil samples under different water content,and the relationship between brittleness index,peak strength,shear strength index and water content was analyzed.The soil water characteristic curves of four soil samples were measured using the filter paper method combined with the Fredlund&Xing model and Van Genuchten model,the shear strength formulas of unsaturated soil with total stress conditions and wide suction range were given,respectively.The results show the shear stress displacement relationship curves of the four types of soil samples increase with the decrease of moisture content;the relationship curves of the sample close to saturation moisture content is hardening type,and gradually transitions to softening type with the decrease of moisture content;when the moisture content is below 14%,it shows a cliff like decline.An improved brittleness index was proposed for the brittle failure phenomenon of samples with low water content.Four types of soil samples were divided into plastic failure zone and brittle failure zone based on the brittleness index of 0.3 and water content of 14%.The peak strength of soil samples can be divided into two stages as the water content decreases:stable growth zone and fluctuating growth zone,with a water content of 14%as the boundary.As the water content increases,the shear strength indicators such as cohesion and internal friction angle generally show a decreasing trend.the improved unsaturated soil strength formula with a wide suction range was used to fit the experimental data,and degree of fitting reached above 0.844.The research results provide theoretical basis and technical support for monitoring,warning,and prevention

关 键 词：梯田型黄土滑坡隐患 抗剪强度 脆性指数 非饱和土 土力学 

分 类 号：TU444[建筑科学—岩土工程]