不同冻结温度条件下膨胀土冻融循环试验

Test of freeze-thaw cycle of expansive soil under condition of different freezing temperatures

为了研究冻融循环次数与冻结温度对膨胀土物理力学性质的影响规律,以南阳中膨胀土为试验对象,在不同冻融循环次数和冻结温度条件下对膨胀土试样进行变形测量和无侧限压缩试验。试验结果表明:膨胀土试样在冻融循环过程中体积变化表现为"冻缩融胀",随着冻融循环次数的增多,试样的冻缩量和融胀量渐趋稳定,不同的冻结温度会改变试样的残余孔隙比。冻融循环作用对膨胀土的力学性质有着显著的影响,其第一次最为强烈,在冻融循环过程中,膨胀土试样的应力应变曲线形态显得越来越"瘦小",破坏应变、无侧限抗压强度和弹性模量等参数均逐渐减小,当冻结温度为-10℃时,膨胀土的力学参数受冻融循环作用的影响最大。

In order to reveal the rule of influence of freeze-thaw cycles and freezing temperature on physical and mechanical properties of expansive soil,the paper took Nan Yang expansive soil as test object,and carried out deformation measurement and unconfined compressive test under different freeze-thaw cycles and freezing temperatures. The results showed that the volume change for expansive soil samples under freeze-thaw cycle could be expressed as ＂frost shrinking and thaw expanding＂,with the increase of times of freeze-thaw cycles,the amount of frost shrinkage and thaw expansion of samples intended to be stable,the different freezing temperatures could change the residual porosity ratio of the samples. The mechanical properties of expansive soil could be affected by freeze-thaw cycles intensively,especially in the first time. In process of freeze-thaw cycle,the stress-strain curves of expansive soil samples became thin increasingly,and its failure strain,unconfined compressive strength and elastic modulus decreased gradually. When freezing temperature is-10 ℃,the influence of freeze-thaw cycles on mechanical properties of expansive soils is the greatest.