摘要
土体动力特性主要与其受力状态、土体加载类型、试验控制方式以及荷载等参数有关。以往非饱和黄土累积变形试验研究通过单向动应力加载方式开展相关研究,并不能真实反映土体受力状态。现运用WF-12440型动三轴-空心圆柱扭剪试验系统,通过单向荷载和双向荷载两种不同的动应力加载方式,进行黄土的长期重复载荷试验,对比不同动应力加载方式对非饱和黄土累积变形发展特征的影响。试验结果发现:黄土在单向荷载或双向荷载作用下,其软化指数均随着循环次数的增加,呈非线性减小的趋势,在相同循环振次时,土体软化指数随着动应力幅值的增大而减小;黄土在不同加载方式作用下,软化指数减小速率在循环振次100次以内较快,后期随振次增加,土体软化速率逐渐趋于平稳;黄土在双向荷载作用下,当轴向动荷载较小时,径向荷载的施加,将加速黄土的软化程度,随着轴向动荷载的增大,径向荷载对黄土软化的影响逐渐减弱,其对于黄土变形的影响存在一临界轴向循环动应力。本研究的开展,可更准确地进行不同荷载耦合变化下,黄土场地震陷评估或路基土体变形计算,实现有效控制路基的整体稳定和工后沉降量,以期根据路基土参数预测后期沉降,极具重要的科研和工程意义。
The dynamic characteristics of soil are mainly related to the stress condition,loading type,test control mode,load,and other parameters.Previous experimental study on the cumulative deformation of unsaturated loess under uniaxial dynamic stress loading can not truly reflect the stress state of soil.In this study,the WF-12440 dynamic triaxial-hollow cylinder torsional shear test system produced by WF Company,UK,was used to carry out a series of long-term repeated load tests of loess under unidirectional and bidirectional dynamic stress loads.The effects of different dynamic stress loading methods on the development characteristics of cumulative deformation of unsaturated loess.The test results showed that the softening index of loess decreases non-linearly with the increase of cycle times both under unidirectional and bidirectional loading.At the same cycle times,the softening index decreases with the increase of dynamic stress amplitude.Under different loading modes,the softening index decreases rapidly within 100 cycles,and the softening rate tends to be stable with the increase of cycles.Under the action of bidirectional load,when the axial dynamic load is small,the application of radial load will accelerate the softening degree of loess;with the increase of axial dynamic load,the effect of radial load on soil softening will weaken gradually.With the development of this study,it can be more accurate to evaluate the seismic subsidence of loess field or calculate the deformation of subgrade soil under different load coupling changes in Northwest China,so as to effectively control the overall stability of subgrade and the settlement after construction.
作者
车高凤
钟秀梅
马金莲
柴少峰
王平
CHE Gaofeng;ZHONG Xiumei;MA Jinlian;CHAI Shaofeng;WANG Ping(Key Laboratory of Loess Earthquake Engineering of CEA & Gansu Province, Lanzhou 730000, Gansu, China;Hebei Key Laboratory of Earthquake Disaster Prevention and Risk Assessment, Langfang 065201, Hebei, China;Geotechnical Disaster Prevention Engineering Technology Research Center of Gansu Province, Lanzhou 730000, Gansu, China)
出处
《地震工程学报》
CSCD
北大核心
2021年第5期1208-1213,1243,共7页
China Earthquake Engineering Journal
基金
河北省地震灾害防御与风险评价重点实验室开放基金(FZ213204)
中国地震局黄土地震工程重点实验室开放基金(KLLEE-17-001)
中国地震局地震预测研究所基本科研业务费专项(2018IESLZ08)
中国地震局地震科技星火计划(XH20058Y)
甘肃省科技计划项目(18YF1FA101)
国家自然科学基金(U1939209,51778590,51578518)。
关键词
黄土
循环三轴试验
轴向动荷载
径向动荷载
软化指数
loess
cyclic triaxial test
axial dynamic load
radial dynamic load
softening index
