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为探究冻融循环过程中软土的冻胀融沉规律、力学性质及力学参数特性,对松花江避暑城战备路工程取样软土进行室内冻融循环试验。通过改变冻融循环次数测定试件体积膨胀与收缩率,并通过室内三轴试验,测得不同冻融循环次数及不同围压条件下的软土抗剪强度。宏观试验数据及微观分析结果表明:冻胀融沉过程中体积变化率随冻融循环次数的增加逐渐增大,6次冻融循环后,土体冻胀率、收缩率基本保持不变,冻胀融沉现象趋于稳定;随着冻融循环次数的增加,软土抗剪强度先增大后减小,且在第6次冻融循环作用下达到最小值,在后续6~15次冻融循环过程中,抗剪强度逐渐增大,且接近冻融循环作用之前的抗剪强度值;冻融循环作用对软土黏聚力c有显著影响,而内摩擦角φ与冻融循环作用无相关性。
In order to explore the law of frost heaving and thawing, the mechanical properties and the mechanical parameters of soft soil in the process of freeze-thaw cycle, the indoor frozen-thaw cycles of Songhuajiang summer-fighting urban road-preparation equipment were carried out. The volume expansion and shrinkage of the specimens were measured by changing the number of freeze-thaw cycles. The indoor triaxial tests were carried out to determine the shear strength of soft soil under different freezing and thawing cycles and different confining pressures. The results of macro-test and microscopic analysis show that the volume change rate of frost heaving and thawing gradually increases with the increase of the number of freeze-thaw cycles. After six freeze-thaw cycles, the frost heaving rate and shrinkage rate of soil remain the same, With the increase of the number of freeze-thaw cycles, the shear strength of soft soil first increases and then decreases, and reaches the minimum under the effect of the sixth freeze-thaw cycle. In the subsequent 6 to 15 freeze cycles In the process of thawing, the shear strength increases gradually and approaches the shear strength before the freeze-thaw cycle. The freeze-thaw cycle has a significant effect on the cohesion c of soft soil, while the friction angle φ and the freeze-thaw cycle No correlation.