自然氧化弱膨胀土的剪切破坏特征试验研究  

Experimental study on shear failure characteristics of weak expansive oxidized soil under atmospheric conditions

作　　者：南亚林[1,2] 郭鸿 陈栋梁[3,4] 陈文涛[3,4] NAN Yalin;GUO Hong;CHEN Dongliang;CHEN Wentao(China Electronic Research Institute of Engineering Investigations and Design,Xi’an 710054,China;Soil Engineering Technology Research Center of Shaanxi,Xi’an 710054,China;School of Civil Engineering and Architecture,Shaanxi University of Technology,Hanzhong 723000,China;Research Center of Geotechnical Environment and Geological Hazards Control in Qinling-Daba Mountains,Shaanxi University of Technology,Hanzhong 723000,China)

机构地区：[1]信息产业部电子综合勘察研究院,陕西西安710054 [2]陕西省土体工程技术研究中心,陕西西安710054 [3]陕西理工大学土木工程与建筑学院,陕西汉中723000 [4]陕西理工大学秦巴山地岩土环境与灾害防治研究中心,陕西汉中723000

出　　处：《水利水运工程学报》2022年第4期97-105,共9页Hydro-Science and Engineering

基　　金：陕西省重点研发计划项目(2019ZDLSF05-07,2020SF-430);信息产业部电子综合勘察研究院科研项目(2020-DKY-W02)。

摘　　要：膨胀土体材料在大气环境下自然氧化,其黏粒的化学成分、矿物组分和颗粒结构将发生变化。通过XRF成分检测及室内土工试验方法,研究了不同围压条件下原状土样与氧化土样的剪切变形破坏规律,用硬化系数量化分析了土样从压缩硬化过渡到压剪混合破坏模态的非线性软化特征。结果表明:原状土样氧化后抗剪指标有所增强,内摩擦角变化是抗剪强度增加的关键因素。原状土样和氧化土样的剪切破坏机制较为复杂,在试验设定加载条件下,可能发生鼓曲状压缩、硬化压缩、压剪混合或剪切滑移等各类破坏模态。硬化系数可对土样加载过程中的剪切应力应变关系曲线进行量化,体现压缩硬化向压剪混合及剪切软化破坏模态过渡的非线性变化特征。可为膨胀土氧化效应研究及其土体稳定性分析提供一定的理论参考。Under atmospheric environment conditions,the natural oxidation of expansive soil may occur,and the chemical composition,mineral composition and particle structure of clay particles may change.In order to study the effect of atmospheric oxidation on the physical properties of Liulin weak expansive soil,the chemical components of undisturbed soil and oxidized soil clay were compared by XRF component detection and laboratory geotechnical test methods.The shear deformation and failure modes of undisturbed soil and oxidized soil samples were studied under different confining pressures.The hardening characteristics of soil samples under compression and shear failure modes were analyzed by the principal stress-strain constitutive relation.The results show that the key factor is the change of the internal friction angle for the increase of the shear strength index.Under the experimental loading conditions,the failure modes of undisturbed soil samples and oxidized soil samples are different,and various failure modes may occur,such as buckling compression,hardening compression,compression and shear mixing,or shear slip.For soil materials with softening properties,the hardening coefficient can be used to describe the nonlinear characteristics of the sample transition from compression hardening to compression shear mixing and shear softening failure mode.This paper can provide a theoretical reference for the study of the oxidation effect of expansive soil and the analysis of its engineering stability.

关 键 词：弱膨胀土 大气氧化 化学成分 破坏模态 硬化系数 

分 类 号：TU41[建筑科学—岩土工程]