不同压实系数下冻融软土力学特性及孔隙特征研究  

Mechanical Properties and Pore Characteristics of Freeze-thaw Soft Soil Under Different Compaction Coefficients

作　　者：唐小东 陈峰 张晗辉 张金鑫 邵承贵 张俊寒 TANG Xiaodong;CHEN Feng;ZHANG Hanhui;ZHANG Jinxin;SHAO Chenggui;ZHANG Junhan(China United Engineering Co.Ltd.,Hangzhou 310000,China)

机构地区：[1]中国联合工程有限公司,杭州310000

出　　处：《河南科学》2024年第3期355-365,共11页Henan Science

基　　金：浙江省重点研发计划(2022C03082)。

摘　　要：季节性冻土地区的路基材料在反复冻融下易发生性能劣化,为了解冻融循环作用下软黏土的力学性质和微观结构特性变化,考虑压实系数、围压、冻融循环次数等因素,对东北地区软黏土进行三轴试验以及核磁共振试验.研究结果表明,不同压实系数的土样的峰值强度与围压呈正相关关系,且强度曲线近似呈线性分布,而峰值强度差值随着围压的增大逐渐减小,当围压增加至300 kPa时,峰值强度增加了约70.8%,而峰值强度差值减小了约44.7%.此外,压实系数对土样弹性模量有着显著的影响,随围压增加土体压实系数与弹性模量呈指数函数变化.同时,围压的增大抑制了由冻胀所产生大孔隙的发育,增强了土体的密实度,进而降低了冻融作用下的土体微观结构的损伤.冻融循环荷载作用下,随着压实系数上升,平均孔径有明显减小趋势,二者呈负相关性.Subgrade materials in regions with seasonally frozen soil are susceptible to degradation during repeated freeze-thaw cycles.Triaxial tests and nuclear magnetic resonance tests were conducted on soft clay in Northeast China to investigate the mechanical properties and microstructural characteristics under freeze-thaw cycles,considering compaction,confining pressure,and freeze-thaw cycles as main variables.The results indicate that the peak strength of soil samples increases with higher confining pressure for varying compaction factors,showing an approximately linear strength curve.As confining pressure rises from 100 kPa to 300 kPa,the peak strength can increase by up to 70.8%while the difference in peak strength decreases by about 44.7%.The compaction coefficient significantly affects the elastic modulus of soil samples,with an exponential relationship between the compaction coefficient and elastic modulus under different confining pressures.Increasing confining pressure decreases macropores in the soil,improving soil sample compactness and reducing microstructural damage during freeze-thaw cycles.Higher compaction coefficients result in denser soil samples with smaller particle gaps.With an increased compaction coefficient,the average pore diameter decreases,showing a negative correlation between the two under freeze-thaw loading.

关 键 词：软黏土 冻融循环 压实系数 微观结构 孔径分布 弹性模量 

分 类 号：TU433[建筑科学—岩土工程]