冀南黄土状土分布和动力特性研究  

Study on distribution and dynamic characteristics of loess soil in southern Hebei

作　　者：刘义轩 李金秋[1,2] 王振兴 杜国梁[3] 侯新伟 左雪峰 白占学[1,2] LIU Yixuan;LI Jinqiu;WANG Zhenxing;DU Guoliang;HOU Xinwei;ZUO Xuefeng;BAI Zhanxue(Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang,050061;Quaternary Geochronology and Hydrological Environment Evolution Key Laboratory of China Geological Survey,Shijiazhuang,050061;Hebei GEO University,Shijiazhuang,050031)

机构地区：[1]中国地质科学院水文地质环境地质研究所,石家庄050061 [2]中国地质调查局第四纪年代学与水文环境演变重点实验室,石家庄050061 [3]河北地质大学,石家庄050031

出　　处：《地质论评》2025年第2期579-589,共11页Geological Review

基　　金：中国地质调查局地质调查项目(编号:DD20230539);河北省教育厅高等学校自然科学研究重点项目(编号:ZD2022094)的成果。

摘　　要：穿越黄土状土地区的铁路,在列车荷载长期作用下极易发生沉降。笔者等以冀南黄土状土为研究对象,通过野外调查、人工探井、室内试验测试等方法,探明了黄土状土的分布特征和湿陷等级。针对铁路穿越区广泛分布的中等湿陷性黄土状土,采用动三轴仪分别开展了单样多级加载和平行多样恒定幅值动力加载试验,研究了黄土状土在不同固结比、围压、动应力、振动频率条件下的变形破坏特征,并与不同等级湿性土进了对比。得出了以下主要结论:①冀南东部平原黄土状土湿陷性程度轻微—中等,局部强烈,西部地区和山前台地黄土状土湿陷程度强烈,轻微、中等、重度湿陷性土面积占比分别为:4.9%、21.8%、8.5%,湿陷系数(δs)最大可达0.14;②动应力大小是影响中等湿陷黄土状土变形的一个重要因素,土体产生破坏前后存在一个临界动应力比,介于0.37~0.38,当动应力比小于临界值时,试样出现了应变硬化现象,超过临界值后,试样应变软化现象显著;③在列车荷载相同的情况下,列车振动频率越高,土体动应变越小但是变幅减缓;④相同条件下,黄土状土轴向动应变随δs的减小呈缓慢减小趋势,与非湿陷性土相比变化尤为显著,差值最大达1.02%。研究成果对黄土状土地区城市轨道建设路基灾害的防治以及相关领域的研究具有参考意义。Objective:The railway passing through the loess soil area is prone to settlement under the long-term action of train load.In this paper,the distribution characteristics and dynamic characteristics of loess soil in southern Hebei are studied.Methods:In this study,through investigations and indoor geotechnical tests,the distribution characteristics of loess-like soil in southern Hebei were proved.andthe physical and mechanical properties of different types of loesslike soil were tested.On the basis of field investigation and indoor geotechnical test,single-sample multi-stage loading and parallel multi-constant amplitude dynamic loading tests were carried out on the medium collapsible loess-like soil mainly passed by the railway by using dynamic triaxial tester.The deformation and failure characteristics of loess soil under different consolidation ratio,confining pressure,dynamic stress,vibration frequency and collapsibility grade were studied.Results:The main achievements are as follows:①The degree of collapsibility of loess-like soil in the eastern plain in southern Hebei is slight to moderate,and the local area is strong.The degree of collapsibility of collapsible soil in western region and piedmont platformis strong,and the coefficient of collapsibility is 0.14.②The dynamic stress is an important factor affecting the deformation of loess-like soil.There is a critical dynamic stress value when the soil is damaged.When the dynamic stress is less than the critical value,the sample hardening phenomenon occurs.After exceeding the critical value,the sample softening phenomenon is significant.③When the train load is the same,the higher the speed of the train,the smaller the strain of the soil but the increase is reduced.④The critical dynamic stress ratio of loess soil decreases with the increase of collapsibility coefficient,and the critical dynamic stress ratio decreases obviously compared with that of non-collapsible soil.Conclusions:The research results have reference significance for the prevention and cont

关 键 词：冀南地区 黄土状土 湿陷性 列车荷载 动三轴试验 变形特征 

分 类 号：TU4[建筑科学—土工工程]