从非饱和土力学角度探讨黄土湿陷机制
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摘要
本文回顾了黄土湿陷概念的由来及其基于其微结构湿陷机制研究现状。对从非饱和土力学角度开展黄土湿陷机理研究的有关问题进行了讨论和分析,提出了广义湿陷性概念。黄土湿陷机制研究应根据具体湿陷路径针对性开展非饱和土应力路径试验研究,从而进一步建立黄土广义湿陷本构模型,为工程问题的定量分析和数值计算提供科学依据。非饱和黄土常剪应力增湿试验表明,黄土湿陷破坏之前发生了一定的微小变形,随后应变速率突然增加,偏应力也不再维持为常数。同时,观察到孔压突然上升1~2kPa,表明黄土湿陷过程发生了不完全排水剪缩破坏。
The paper reviews the concept origin of loess collapsibility and the research status of collapsibility mechanism based on its microstructure,and discusses on the collapsibility mechanism from the perspective of unsaturated soil mechanics,then puts forward the concept of generalized collapsibility.It is suggested that research of loess collapsibility includes the laboratory investigations based on field collapsibility stress-path and then building of constitutive model,as a base for engineering quantitative analysis and numerical simulation.One series(3 samples) loess moistening test under dead load shows that collapse occurs so suddenly at less than 1% of axial strain that deviatoric stress can not retain.Meanwhile,about 1～2kPa pore pressure raise is observed,indicating incompletion drained shear failure occurring in the collapse process.
The paper reviews the concept origin of loess collapsibility and the research status of collapsibility mechanism based on its microstructure,and discusses on the collapsibility mechanism from the perspective of unsaturated soil mechanics,then puts forward the concept of generalized collapsibility.It is suggested that research of loess collapsibility includes the laboratory investigations based on field collapsibility stress-path and then building of constitutive model,as a base for engineering quantitative analysis and numerical simulation.One series(3 samples) loess moistening test under dead load shows that collapse occurs so suddenly at less than 1% of axial strain that deviatoric stress can not retain.Meanwhile,about 1～2kPa pore pressure raise is observed,indicating incompletion drained shear failure occurring in the collapse process.
引文
[1]孙建中.黄土的湿陷性及其与湿度的关系[J].水文地质工程地质,1957(11):18-21.
[2]孙广忠.中国西北几个地区黄土性质的初步研究[J].水文地质工程地质,1957(5):1-8.
[3]郭见杨.关于湿陷原因的研究[J].水文地质工程地质,1958(4):7-11.
[4]林在贯,舒天开.西北黄土之湿陷性之初步探讨[J].水文地质工程地质,1958(4):1-7.
[5]高国瑞.兰州黄土显微结构和湿陷机理的探讨[J].兰州大学学报,1972(2):123-134.
[6]高国瑞.中国黄土的微结构[J].科学通报,1980a,(20):945-948.
[7]高国瑞.黄土的显微结构分类与湿陷性[J].中国科学,1980b(12):1203-1208.
[8]高国瑞.中国黄土的微结构与地理、地质环境的关系[J].地质学报,1984(3):265-272.
[9]高国瑞.黄土湿陷变形的结构理论[J].岩土工程学报,1990,12(4):1-10.
[10]杨运来.黄土湿陷机理的研究[J].中国科学(B辑),1988(7):756-766.
[11]雷祥义.黄土显微结构类型与物理力学性质指标之间的关系[J].地质学报,1989(2):182-191.
[12]陈正汉,刘祖典.黄土的湿陷变形机理[J].岩土工程学报,1986,8(2):1-12.
[13]袁中夏,王兰民,王峻.考虑非饱和土与结构特征的黄土湿陷性讨论[J].西北地震学报,2007,29(1):12-17.
[14]Sivakumar V.A critical state framework for unsaturatedsoils[D].PhD Thesis,University of Sheffield,1993.
[2]孙广忠.中国西北几个地区黄土性质的初步研究[J].水文地质工程地质,1957(5):1-8.
[3]郭见杨.关于湿陷原因的研究[J].水文地质工程地质,1958(4):7-11.
[4]林在贯,舒天开.西北黄土之湿陷性之初步探讨[J].水文地质工程地质,1958(4):1-7.
[5]高国瑞.兰州黄土显微结构和湿陷机理的探讨[J].兰州大学学报,1972(2):123-134.
[6]高国瑞.中国黄土的微结构[J].科学通报,1980a,(20):945-948.
[7]高国瑞.黄土的显微结构分类与湿陷性[J].中国科学,1980b(12):1203-1208.
[8]高国瑞.中国黄土的微结构与地理、地质环境的关系[J].地质学报,1984(3):265-272.
[9]高国瑞.黄土湿陷变形的结构理论[J].岩土工程学报,1990,12(4):1-10.
[10]杨运来.黄土湿陷机理的研究[J].中国科学(B辑),1988(7):756-766.
[11]雷祥义.黄土显微结构类型与物理力学性质指标之间的关系[J].地质学报,1989(2):182-191.
[12]陈正汉,刘祖典.黄土的湿陷变形机理[J].岩土工程学报,1986,8(2):1-12.
[13]袁中夏,王兰民,王峻.考虑非饱和土与结构特征的黄土湿陷性讨论[J].西北地震学报,2007,29(1):12-17.
[14]Sivakumar V.A critical state framework for unsaturatedsoils[D].PhD Thesis,University of Sheffield,1993.
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