砂土高压蠕变微观机理分析

Microscopic Analysis of Sand Creep in High Pressure

砂土层在地面沉降过程中呈现一定的蠕变特性。文章采用一维压缩试验对4 MPa下砂土的变形特征进行了研究,并采用改进的试验装置对砂土的微观结构进行了提取。通过对8组不同级配砂土样的蠕变特性和微观结构分析,得到如下结论:粒径单一的砂土在蠕变过程中更容易出现突变,砂粒受力后更容易发生破碎,产生滑移错动;砂土蠕变的蠕变量与砂粒级配密切相关,砂土的粒径越单一且粒径越大时,砂土的蠕变量也越大;采用表征砂土颗粒形状复杂程度的形状系数,从微观上定量分析了砂土在蠕变过程中发生破碎的情况和蠕变量大小,且形状系数越小,表明该种砂土形状越复杂,在蠕变过程中砂土的破碎性越高,蠕变量越大。

The sand layers exhibit the characteristics of creep to some degree during the land subsidence. In this paper, we studied thecharacteristics of sand deformation, using one-dimensional compression test under the condition of 4 MPa and extracted themicrostructure of sand by improving the test device. Through analyzing the creep characteristics and microstructures of 8 sand samples,the following conclusions are obtained: sands with a single size have higher possibility to lead to sudden deformations and sands brokenwhich cause the slippage and position change of sands; The characteristics of deformation of sands are closely related to the grading ofsands which have higher possibility to cause more deformations and sudden changes when the sands size is large; Using the formalfactor of sands from micro-perspective to analyze the sands particles, we found that the smaller the formal factor of sands is, the higherpossibility of broken and the larger deformations of sands are.