三轴条件下软土的微观结构损伤特征  

Microstructure Damage Characteristics of Soft Soil Subjected to Triaxial Loading

作　　者：唐雪明 孙红[2] TANG Xueming;SUN Hong(Guiyang Oil and Gas Transmission Branch,Southwest Oil and Gas Pipeline Co.Ltd.,Pipe China Group,Guiyang 550081,China;School of Ocean and Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]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 [2]上海交通大学船舶海洋与建筑工程学院,上海200240

出　　处：《石家庄铁道大学学报（自然科学版）》2024年第4期51-56,共6页Journal of Shijiazhuang Tiedao University(Natural Science Edition)

基　　金：国家自然科学基金(41572255)。

摘　　要：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。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 microscopic structure evolution mechanism of natural soft soil.The results show that microscopic structure 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 distribution 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.

关 键 词：软土 微观结构损伤 土粒 孔隙 分维数 

分 类 号：TU431[建筑科学—岩土工程]