膨胀土干湿循环作用下的动力特性试验研究

为研究干湿循环作用下膨胀土的动力特性,对干湿循环条件下膨胀土进行动三轴试验,研究了围压、干湿循环次数、振动次数对于膨胀土动弹模量、阻尼比的影响规律。试验结果表明,土体在动荷载作用下的变形分为稳定型和破坏型,稳定型土体的动弹模量随振动次数增加而略有增加,阻尼比则有减小趋势,破坏型土体在较少的振动次数下很快达到破坏应变。建立了膨胀土的累积变形预测模型,可用于分析土体的累积变形随振动次数的变化规律。不同动应力条件下,土体的滞回圈形态从稀疏到密集,面积逐渐减小,较大应力作用下滞回圈的高度随振动次数的增加逐渐降低。首次干湿循环后对土体的影响最为显著,随后影响趋势逐渐减弱,随着干湿次数的增加,相同应力条件下土体需更多的振动次数才能保持稳定。

Experimental Research on Dynamic Characteristics of Expansive Soil under Dry wet Cycle

The dynamic triaxial tests were carried out to study the dynamic characteristics of expansive soils under dry wet cycling. The effects of confining pressure, number of dry wet cycles and number of vibrations on the dynamic elastic modulus and damping ratio of expansive soils were studied. The experimental results show that the deformation of expansive soils under dynamic loading can be divided into stable type and broken type. The dynamic elastic modulus of stable soil increases slightly with the increase of vibration times, while the damping ratio decreases, and the failure strain of destructive soil quickly reaches the failure strain with less vibration times. A prediction model of cumulative deformation of expansive soil was established to analyze the variation of cumulative deformation of expansive soil with the number of vibration. Under different dynamic stress conditions, the shape of hysteretic loops decreases gradually from sparse to dense, and the height of hysteretic loops decreases gradually with the increase of vibration times under larger stress. After the first dry wet cycle, the influence on the soil is most significant, and then the influence trend gradually weakens. With the increase of the number of dry wet cycles, the soil needs more vibration times to maintain stability under the same stress conditions.