冻融循环对GCL渗透特性的影响

Effect of Freeze-Thaw Cycles on Hydraulic Permeability of GCL

为探究土工复合膨润土垫(GCL)在长期冻融循环作用下的防渗性能,以6 h的冷冻和6 h的融化为冻融周期对GCL进行冻融循环试验,研究了经历不同冻融次数后GCL渗透系数和自由膨胀率的变化规律.试验结果表明:4 h内GCL可以达到冻胀稳定状态;GCL经历冻融循环作用后,再经历冻结时易产生不均匀冻胀;GCL在经历较少(≤30次)冻融循环次数情况下,渗透系数随冻融循环次数增加而减小,其最终渗透系数的量级在10-11~10-10m/s之间;随着冻融循环次数的增加,GCL中膨润土的自由膨胀率先增大后减小,最后趋于稳定.

To analyze the anti-seepage performance of geosynthetic clay liner(GCL)after long-term freeze-thaw cycles,the 6-hour freezing and 6-hour thawing cycle tests on GCL material were carried out.The permeability coefficient and free swelling ratio of GCL after different freeze-thaw cycles were studied.The results show that the frost heave of GCL can reach a stable state within 4 h,and when frozen again,differential frost heave can occur in the GCL sample after freeze-thaw cycles.When the number of freeze-thaw cycles is low(≤30 times),the permeability coefficient of GCL decreases with increase of the number of freeze-thaw cycles,and the permeability coefficient is between 10-11 m/s and 10-10 m/s.As the number of freeze-thaw cycles increases,the free swelling ratio of bentonite in GCL increases first,then decreases and finally reaches a steady value.