冻融循环下废旧轮胎颗粒改性膨胀土无侧限抗压强度试验

为了研究膨胀土的无侧限抗压强度与橡胶颗粒含量、冻融循环次数之间的关系,在控制含水率一定的条件下,对经历冻融循环的废旧轮胎颗粒改性膨胀土试样进行无侧限抗压强度试验。试验结果表明在膨胀土中加入橡胶颗粒可在一定程度上提高膨胀土的无侧限抗压强度,并能降低其刚性;在同一冻融循环次数下,改性膨胀土的无侧限抗压强度随着橡胶颗粒含量的增大呈现先增大后减小的趋势,当橡胶颗粒含量为3%时,橡胶颗粒改性膨胀土的无侧限抗压强度最大;在同一橡胶颗粒含量下,改性膨胀土的无侧限抗压强度以及单次冻融循环对试样强度削弱作用均随冻融循环次数的增加而减小;当含水率为20%时,冻融循环条件下,改性膨胀土试样的尺寸变化率随橡胶颗粒含量的增大总体呈增大趋势;橡胶颗粒含量较低情况下(≤7%),膨胀土尺寸变化规律为“冻缩融胀”;橡胶颗粒含量较高情况下(9%),膨胀土尺寸变化规律为“冻胀融缩”。

Unconfined Compressive Strength Test on Expansive Soil Improved byWaste Tire Rubber Particles under Freeze-thaw Cycles

In order to investigate the relationship among unconfined compressive strength of expansive soil improved by waste rubber particles, rubber particle ratio and freeze-thaw cycle times,we conducted unconfined compressive strength test on expansive soil samples improved by waste tire rubber particles at given water content.Results show that adding rubber particles could improve the unconfined compressive strength to some extent and reduce the stiffness.When the number of freeze-thaw cycle was the same, the unconfined compressive strength of the improved expansive soil increased and then decreased with the increasing of rubber particle ratio.In particular, unconfined compressive strength reached the maximum when rubber particle ratio was 3%.When rubber particle ratio was the same, unconfined compressive strength of the expansive soil and the influence of single freeze-thaw cycle on strength weakening both decreased with the increase of freeze-thaw cycle times.When water content was 20%,the rate of change in expansive soil size increased in general with the increase of rubber particle ratio in freeze-thaw cycles.Finally, when rubber particle ratio was low (≤7%), the size of the expansive soil shrank under freezing and expanded under thawing;while when rubber particle ratio was higher (=9%), the change was the opposite.