颗粒尺度对土体变形 和强度影响的三轴排水抗剪试验与分析

房营光 吴宇航 谷任国

摘 要：土体为具有结构性的多孔介质，其颗粒尺度及其分布范围直接影响土的孔隙特征和结构性，进而影响土中孔隙水压力消散以及强度和变形特性。对不同颗粒成分的土样进行三轴排水抗剪试验，分析颗粒尺度对土体变形和强度的影响规律，认识相应影响机理和作用机制。三轴试验给出了不同颗粒比例和尺度、不同围压下的主应力差-轴向应变关系的CD和CU试验曲线，基于实验结果提出土体的胞元模型对土体的强度和变形特性的颗粒尺度影响机制并进行相应分析，进一步加深对颗粒尺度效应的理解。

关键词：颗粒尺度效应;三轴排水抗剪试验;物理作用机制;有效应力;土胞元体模型

中图分类号：TU43 文献标识码：A     文章编号：1001-5922（2021）10-0172-06

Triaxial Drainage Shear Tests and Analysis of the Influence of Particle Size on Soil Deformation and Strength

Fang Yingguang1， Wu Yuhang1， Gu Renguo1，2

（1.School of Civil Engineering and Transportation ， South China University of Technology， Guangzhou 510641， China; 2.State Key Laboratory of Subtropical Building Science， South China University of Technology， Guangzhou510641， China）

Abstract：The soil is a structured porous medium. Its particle size and distribution range directly affect its pore characteristics and structure， which in turn affects dissipation of pore water pressure in the soil， as well as soil strength and deformation characteristics. In this paper， a triaxial drainage shear test is performed on soil samples with various particle compositions， it is used to analyze the influence of particle size on soil deformation and strength and to understand the corresponding influence and action mechanisms. The triaxial test gives the CD and CU test curves of the principal stress difference-axial strain relationship under different particle ratios and sizes， and different confining pressures. Based on the experimental results， the cell model of the soil is proposed for the strength and deformation characteristics of the soil. The impact mechanism of particle size of the particle size and the corresponding analysis are carried out to further deepen the understanding of the particle size effect.

Key words：particle sizeeffect ; tri-axial shear test ; physical mechanism ; effective stress ; soil cell element model

0 前言

土是一種天然的多相材料，大小不同的颗粒排列和分布形成土的结构性，而结构性主导土的工程性质[1-3]。试验研究表明，微细观尺度下的土体具有与传统宏观连续土体不同的特性，表现出如颗粒尺度强烈效应等一些宏观土体不具有的性质[4，5，6]，如颗粒性和结构特性导致的不连续性，非线性和多尺度特征[7-10]。颗粒尺度效应主要通过颗粒之间的物理化学相互作用而产生，如颗粒界面上的相互摩擦和挤压、水溶液和气体在界面上吸附、颗粒间的化学胶结等，这些物理化学相互作用通过颗粒界面进行，因而颗粒的大小尺度、比表面积及界面性质（如亲/疏水性）对颗粒尺度效应的影响是至关重要的[10]。……