工程地质学报2023，Vol.31Issue(6)：1820-1832,13.DOI:10.13544/j.cnki.jeg.2022-0007
三轴循环荷载下土石混合体细观结构劣化实时CT扫描试验研究
ON MESO-STRUCTURAL CHANGES OF BIMSOIL UNDER TRIAXIAL CY-CLIC LOADS USING IN-SITU X-RAY COMPUTED TOMOGRAPHY(CT)
摘要
Abstract
This paper aims to investigate the structural deterioration characteristics and mesoscopic damage evolu-tion process of blocks-in-matrix-soils(bimsoils)under triaxial cyclic loading.An industrial CT machine equipped with a self-designed loading device is used to carry out low-confining pressure in-situ CT scanning tests on bimsoil samples with block content of 30％,40％and 50％,respectively.The effects of rock content on macroscopic stress-strain curve,hysteretic loop pattern,crack geometry parameters and dilatancy effects are revealed.Testing results show that the cyclic loading and unloading results in the increase of plastic strain,and the stress hysteresis cycle presents a sparse-dense-sparsity pattern.Under the same stress amplitude,the existence of rock blocks in soil ma-trix has a certain influence on the shape of hysteresis loop.The area of hysteresis loop decreases with the increase of block content.When the block content is higher,the skeleton effect formed by the interactions between the soil ma-trix and rock is enhanced,and the energy dissipation in the process of structural weakening of bimsoil is weakened.A series of image processing algorithm are used to extract the rocks and cracks of samples under different loading stages.Under the same loading weeks,the damage degrees of bimsoil samples with different block contents are dif-ferent,and the statistical area of cracks decreases with the increase of the content of rocks.Due to the high elastic mismatch between soil and rock mass,strain localization of bimsoil results in the difference of dilatancy behavior.The propagation of cracks and the formation of macroscopic failure surface are greatly affected by the rock block percentage.The volumetric dilatancy of bimsoil decreases with the increase of the rock block content.The testing re-sults would be helpful for the development of the damage and degradation theory of bimsoil under stress disturb-ance,and provide theoretical support for the engineering construction and disaster prevention of geological mass composed of bimsoil.关键词
土石混合体/三轴循环荷载/结构劣化/CT扫描/含石量Key words
Bimsoil/Triaxial cyclic loads/Structure deterioration/CT scanning/Rock block percentage分类
建筑与水利引用本文复制引用
王宇,李晓,毛天桥,易雪枫,孙涛..三轴循环荷载下土石混合体细观结构劣化实时CT扫描试验研究[J].工程地质学报,2023,31(6):1820-1832,13.基金项目
北京市自然科学基金(资助号:8202033),国家自然科学基金项目(资助号:52174069),中央高校基本科研业务项目(资助号:FRF-TP-20-004A2).This research is supported by the Beijing Natural Science Foundation(Grant No.8202033),National Natural Science Foundation of China(Grant No.52174069)and the Fundamental Research Funds for the Central Universities(Grant No.FRF-TP-20-004A2). （资助号:8202033）
