黏粒含量对粉土抗压强度的影响

Influence of Clay Content on Compressive Strength of Silt

选用山东省齐河地区黄河冲击平原粉土,湖南的黏粒(红黏土)为原料,特制一种接近于粉土中黏粒的黏土,考虑到粉土中黏粒对土体的整体黏结性具有一定影响,采用宏观与细观结合的分析方法,研究黏粒对粉土抗压强度的影响。结果表明:粉土在非浸水条件下的无侧限抗压强度随黏粒含量的增加呈先减小后增大的趋势,在黏粒内掺掺量为6%时达到最低;通过离散元模拟试验,对加载破坏后的虚拟试件进行裂隙分析,得到黏粒含量的增加,可延缓裂隙在土体内部延伸,减少裂缝的产生;结合试件破坏后的力链分布状况,分析了黏粒掺量在0%,6%,24%时的土体内黏结力链分布状态,随黏粒掺量的逐渐增加,力链逐渐增多密集,土体内部的黏结力分布也逐渐增多,则抵抗变形的能力逐渐增强,揭示了不同黏粒含量对粉土抗压强度的细观作用机理,对今后土基所用填土的性能评价、强度合理化设计等工程应用方面将起到一定的参考利用价值。

By selecting silty soil from Yellow River alluvial plain in Qihe area of Shandong province and clay particles(red clay)from Hunan province,clay are made by the clay particles dound in silty soil.Considering that the clay in silt has a certain influence on the overall cohesiveness of soil,it studies the influence of clay on the compressive strength of silt by combining macro and micro analysis methods.The results show that the unconfined compressive strength of silt decreases first and then increases with the increase of clay content under non-soaking conditions and reaches the lowest when the clay content is 6%.In the discrete element simulation test,the fracture analysis of the virtual specimen after loading failure shows that the increase of clay content can delay the fracture extension in the soil and reduce the occurrence of cracks;combined with the distribution of force chain after failure,the distribution of cohesive force chain in soil with clay content of 0%,6%,24%is analyzed.With the increase of clay content,the force chain increases and becomes more dense gradually,the distribution of cohesive force in the soil increases gradually,and the ability to resist deformation gradually increases,which reveals the microscomic mechanism of different clay content on the compressive strength of silt.It has a certain reference value for engineering application such as performance evaluation and strength rationalization design of fill used in soil foundation in the future.