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三轴条件下软土的微观结构损伤特征

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开展应力控制式三轴固结不排水剪切试验和场发射电镜扫描试验,研究天然软土的宏微观的受力全过程变化特征,揭示天然软土在剪切过程中微观结构的变化.结果表明,土体的微观结构在受力过程中不断地发生损伤,大中孔隙的数目增多,孔隙和土粒的分布更加松散,因此软土的微观损伤是土粒和孔隙分布变化的综合反映.孔隙和土粒的分布分维数等参数与剪应力比呈非线性关系,具有明显的拐点,拐点后孔隙和土粒的分布分维数明显地增大.剪切带附近大中孔隙多于带外,孔隙与土粒的分布分维数大,但是破坏时各位置的分布维数值接近一个临界值.在剪应力比为 1.22 时,孔隙的临界值约为 1.70,土粒的临界值约为 1.92.
Microstructure Damage Characteristics of Soft Soil Subjected to Triaxial Loading
Stress-controlled triaxial undrained shearing tests and field emission electron microscopy scanning tests were carried out for natural soft soil in order to study the macroscopic and microscopic evolution characteristics during the whole process subjected to the triaxial loading,and to reveal the mi-croscopic structure evolution mechanism of natural soft soil.The results show that microscopic struc-ture continually undergoes damage during the stress process,with an increase in the number of large-sized and medium-sized pores and a looser distribution of pores and soil particles.Therefore,the micro damage of soft soil is a comprehensive reflection of the changes in soil particles and pores distribution.The distribution fractal dimensions of pores and soil particles are nonlinear to shear stress ratio with an obvious turning point.After the point,their distribution fractal dimensions increase significantly.The numbers of large-sized and medium-sized pores near the shear band are much larger than that outside the band,and the distribution fractal dimensions of pore and soil particles is large.However,the distribu-tion fractal dimensions at different positions become close to a critical value at soil failure.When the shear stress ratio is 1.22,the critical values were about 1.70 for pores,1.92 for soil particles.

soft soilmicrostructure damagesoil particleporefractal dimension

唐雪明、孙红

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国家管网集团西南油气管道有限责任公司 贵阳输油气分公司,贵州 贵阳 550081

上海交通大学 船舶海洋与建筑工程学院,上海 200240

软土 微观结构损伤 土粒 孔隙 分维数

2024

石家庄铁道大学学报(自然科学版)
石家庄铁道大学

石家庄铁道大学学报(自然科学版)

CSTPCD
影响因子:0.757
ISSN:2095-0373
年,卷(期):2024.37(4)