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自行设计了冻土冻融循环装置,基于此开展不同上边界冻结温度条件下粉质黏土的冻融循环试验.试验结果表明:1)随冻融次数增加,经高温冻结冻融作用和经低温冻结冻融作用当干密度ρd≤1.42g/cm3时,试样以压密变形为主,而低温冻结冻融作用后ρd>1.42g/cm3的试样则以膨胀变形为主;第2次冻融作用与第1次冻融作用相比,高温冻结冻融作用后的试样融沉系数α0大幅度降低,而低温冻结冻融作用后的试样α0则表现为增加;随冻融次数增加,α0趋于稳定值α07,且α07随上边界冻结温度的增加而增加.2)当上边界冻结温度高于-2.8℃时(包含-2.8℃),不同干密度土样冻融1次后压缩系数mv均降低,当上边界冻结温度低于-2.8℃时,ρd≥1.42g/cm3的试样1次冻融后的mv增大,ρd<1.42g/cm3的试样mv则减小;随冻融次数增加,mv逐渐增大并逐渐趋于稳定值mv7,且mv7随上边界冻结温度的降低而增加.
The freeze-thaw cycle device of frozen soil was designed by ourselves, and the freeze-thaw cycles of silty clay under different freezing temperatures on the upper boundary were carried out.The results showed that: 1) With the increase of freeze-thaw cycles, Frozen and thawed effect When the dry density ρd≤1.42g / cm3, the sample is mainly densified, while the specimens with ρd> 1.42g / cm3 after freeze-thaw freeze-thaw are dominated by expansion and deformation. Compared with the first freeze-thaw action, the thawing and thawing coefficient α0 of the samples after high-temperature freezing and thawing was significantly decreased, while the α0 of the sample after freeze-thaw freezing and thawing activities showed an increase. Α0 tends to the stable value α07, and α07 increases with the freezing temperature of the upper boundary.2) When the freezing temperature of the upper boundary is higher than -2.8 ℃ (including -2.8 ℃), the soil samples with different dry densities freeze-thaw once When the freezing temperature of the upper boundary is lower than -2.8 ℃, the mv after one-time freezing-thawing of ρd≥1.42g / cm3 increases and the mv of samples with ρd <1.42g / cm3 decreases With the increase of the number of freeze-thaw cycles, mv gradually increased and gradually reached a stable value mv7, and mv7 increased with the decrease of the freezing temperature of the upper boundary.