聚丙烯酰胺对石灰稳定土早期强度和破坏形式的影响

Effect of polyacrylamide on early strength and failure form of lime stabilized soil

为了研究聚丙烯酰胺(PAM)对石灰稳定土早期强度和破坏形式的影响,通过承载比(CBR)试验、三轴不固结不排水剪试验及超景深三维显微镜分析不同PAM掺量的PAM-石灰稳定土的早期强度,探索PAM对石灰稳定土的固化机制。研究结果表明:PAM能有效提高石灰稳定土的早期强度,随PAM掺量的增加呈先增后减的趋势;PAM能改善石灰稳定土的脆性破坏特点,出现弱应变硬化现象,但PAM掺量超过0.36wt%时,在50 kPa低围压下,PAM-石灰稳定土又呈现脆性破坏的特点;石灰掺量为8wt%、PAM掺量为0.36wt%时,对土体的改良效果较好,该掺量条件下PAM和石灰共同作用能更好地促进土颗粒团聚,增强土体结构及增加土体表面粗糙度,内摩擦角和黏聚力均提高,抗剪强度也增强。

In order to study the effect of polyacrylamide(PAM)on the early strength and failure form of lime stabilized soil,through the California bearing ratio(CBR)test,triaxial unconsolidated undrained shear test and super depth of field three-dimensional microscope,the early strength of PAM-lime stabilized soil with different PAM contents was analyzed.The solidification mechanism of PAM on the lime stabilized soil was explored.The research indicates that PAM can effectively improve the early strength of the lime stabilized soil.With the increase of PAM content,the early strength of the lime stabilized soil shows a trend of increasing first and then decreasing.PAM can improve the brittle failure characteristics of lime stable soil,and weak strain hardening occurs.But when the PAM content exceeds 0.36 wt%,the lime stable soil exhibits brittle failure characteristics under low confining pressure of50 kPa.When the content of lime is 8 wt%and the content of PAM is 0.36 wt%,the improvement effect of the soil is better.Under the condition of this dosage,the combined action of PAM and lime can better promote the agglomeration of soil particles,strengthen the soil structure and increase the surface roughness of the soil.The internal friction angle and cohesion can be improved and the shear strength will also be enhanced.