非饱和崩坡积混合土动力特性的细粒效应与累积变形研究

Talus mixed gravel soils are widely distributed in the mountains of southwest China, and on the natural slopes, filling bodies and railway and highway embankments consisting of this kind of soil, often exist deformations or sliding, due to seismic loads and traffic loads, causing huge losses. Aimed at the typical talus mixed soils in the lower part of river valleys and gully in western Sichuan, using experimental methods such as unsaturated, static and dynamic large scale triaxial tests, highlighting the two basic characteristics (unsaturation and fine particle content difference), the project carries out a study of the influence of mixed soil moisture content, fine particle content, confining pressure, dynamic shear stress ratio and other factors on dynamic deformation characteristics (dynamic stress-strain relationship, dynamic shear modulus, damping ratio) and dynamic strength characteristics (pore water pressure development, damage vibration times) under cyclic loading, within the range of small strain and large strain. Afterwards, by analyzing theoretically the influence mechanism of different factor, especially the two characteristics on dynamic characteristics, the project aims to grasp the dynamic shear modulus and damping ratio functions used in seismic response analysis, and thus establish a modified unsaturated dynamic constitutive model founded on elasto-plastic boundary surface theory. The constitutive model could be used in traffic load dynamic response analysis by considering the accumulated deformations. This project could provide a theoretical basis and analysis method for the study of the dynamic stability of the structures involving these soils in the mountains of southwest Sichuan or even China.

西南山区广泛分布着崩坡积混合土，由其构成的天然边坡、高填筑体和高速公路铁路路基，常因地震荷载、交通荷载导致变形或滑动，造成了巨大损失。本项目拟针对川西山区河谷及沟谷斜坡下部或坡脚下部位的典型崩坡积混合土，突出非饱和状态和细颗粒含量差异两大特征，通过非饱和、静动大型三轴等实验手段，分别研究小应变和大应变范围内，循环荷载作用下，含水量、细颗粒含量、固结围压、动剪应力比等因素对动变形特性（动应力应变关系、动剪切模量、阻尼比）和动强度特性（孔压发展、破坏振次）的影响规律，理论分析各因素特别是两大特征的影响机理，获得崩坡积混合土地震反应分析中需用的动剪切模量函数与阻尼比函数，并基于弹塑性边界面理论，结合两大特征进行修正，建立可用于该类土交通荷载动力反应分析的、可考虑累积变形的非饱和动本构模型，本项目可为川西山区乃至西南山区混合土结构物的动力稳定性研究提供理论依据与分析方法。

西南山区广泛分布着崩坡积混合土，由其构成的天然边坡、高填筑体和高速公路铁路路基，常因地震荷载、交通荷载导致变形或滑动，造成了巨大损失。本项目针对川西山区河谷及沟谷斜坡下部或坡脚下部位的典型崩坡积混合土，突出非饱和状态和细颗粒含量差异两大特征，通过非饱和、静动大型三轴等实验手段，分别研究了小应变与大应变范围内、地震与交通等效循环荷载作用下，混合土非饱和动变形和动强度随土性条件（初始含水量、细颗粒含量）、静力条件（固结围压、固结应力比）和动力条件（动剪应力比、振动频率）的变化规律，理论分析了各因素特别是两大特征的影响机理，获得了崩坡积混合土地震反应分析中需用的动剪切模量函数与阻尼比函数，并基于弹塑性边界面理论，结合两大特征进行修正，构建了可用于混合土交通荷载动力反应分析的、可考虑累积变形的非饱和动本构模型，本项目成果可为川西山区乃至西南山区混合土结构物的动力稳定性研究提供理论依据与分析方法。