聚乙烯醇改良高原黏土水稳定性实验研究

Experimental Study on Water Stability of Plateau Clay Improved by Polyvinyl Alcohol

为研究聚乙烯醇(polyvinyl alcohol,PVA)对西藏地区黏土的力学性质改良效果,以高分子聚合物PVA为研究对象,改良藏东南地区高原黏土,通过无侧限抗压强度试验,研究PVA的改良效果,在干湿循环及浸水条件下探讨改良土的水稳定性,并利用扫描电镜研究PVA改良黏土的固化机理。结果表明:PVA的加入对黏土的抗压强度及水稳性存在显著影响,PVA掺量越大,黏土干湿循环及浸水后无侧限抗压强度越高,当掺量为0~0.83%时,改良土强度上升最快,而后随着掺量的增加,无侧限抗压强度增长变缓,PVA凝胶脱水后形成弹性立体丝网不再溶于冷水,有效限制土颗粒的位移,使改良土具有良好的抗压强度及水稳性。

In order to study the effect of polyvinyl alcohol(PVA)on the improvement of the mechanical properties of clay in Tibet.Polymer polyvinyl alcohol(PVA)was used as the research object to improve the plateau clay in southeastern Tibet.The unconfined compressive strength test was used to study the improvement effect of PVA and explore the water stability of the improved soil under dry-wet cycles and immersion conditions.The scanning electron microscopy(SEM)was used to study the solidification mechanism of PVA-improved clay.The results show that the addition of PVA has a significant effect on the unconfined compressive strength and water stability of the clay.The greater the amount of PVA added,the higher the unconfined compressive strength of the clay after dry-wet cycles and immersion in water.When the amount is 0~0.83%,the strength of the modified soil increased fastest,and then the growth of unconfined compressive strength decreased with the increasing amount.After the PVA gel is dehydrated,an elastic three-dimensional mesh was formed and no longer dissolved in cold water.The displacement of soil particles was effectively restricted and the unconfined compressive strength and water stability of improved clay was improved.