不同配比砂–粉黏混合料冻后抗压强度试验研究

Research on compressive strength of frozen sand-silty clay mixed soil with different mixture ratios

通过控制变量对砂–粉黏混合料冻结后强度变化规律进行研究,发现粉黏含量对冻土无侧限抗压强度影响显著。细粒土的存在一方面抑制了冰的生成,另一方面相互吸附产生黏聚力,二者此消彼长决定了强度变化。当孔隙间冰晶不能联结成整体,抗压强度将迅速下降。对于所取土样,当干密度保持在1.5 g/cm3,无侧限抗压强度随粉黏含量的增加先增大后减小,最优粉黏含量为60%。含水率的影响亦表现出相同规律,最优含水率为16%。随着干密度的增加,最优粉黏含量与最优含水率均有所减小。冻融循环20次后,无侧限抗压强度较首次冻融降低47%。

In order to study the influence of different mixture ratio on compression strength of sand-silty clay mixed soil,the unconfined compressive tests were conducted on frozen soil samples by means of controlling variables. The experiments indicate that different silty clay contents has remarkable influence on the unconfined compressive strength of frozen soil. Inhabitation of ice and appearance of cohesion,both contributed from increasing of fine soil, mutually interact and determine the strength. Once the ice in pore space fails to combine to a unit,the strength would drop dramatically. Meantime,the maximum unconfined compressive strength can be obtained when clay content is 60% and water content is16%. If the content is below the optimum content,the strength of the frozen soil continuously increases with the content increasing. Otherwise,the strength of the frozen soil gradually reduces with the content increasing. Moreover,the optimum clay content and water content will decrease when dry density increases. Finally,a reduction of unconfined compressive strength,47%,is captured for the mixed soil after 20 freeze-thaw cycles.