干湿环境下膨胀土裂隙演化规律及渠坡变形研究

Evolution pattern of cracks in expansive soil and the deformation of canal slopes in dry and wet environments

研究干湿循环效应下膨胀土裂隙发育规律对揭示膨胀土渠道边坡失稳机制有重要意义。针对目前研究中存在的不足,开展了仅考虑干湿循环效应的膨胀土裂隙演化试验,系统测量了随时间变化的水分蒸发过程及裂隙动态发育特征。基于膨胀土裂隙演化规律,通过编程将块体离散元方法应用至膨胀土渠坡变形分析中,并得到如下结论:(1)膨胀土水分蒸发过程可分为稳定蒸发阶段、减速率蒸发阶段和残余蒸发阶段;(2)随着干湿循环次数增加,膨胀土面积裂隙率逐渐增加后趋于稳定,裂隙总长度逐步增加,裂隙平均宽度不断减小并逐渐稳定,裂隙夹角由T型逐步过渡至Y型;(3)土体颗粒排布总是向稳定方向发育,颗粒间应力分布向着更优势的状态发展,胀缩裂隙分布逐步稳定;(4)将块体离散元应用至膨胀土边坡分析中,实现了考虑裂隙和吸湿膨胀的膨胀土边坡位移场-应力场耦合;(5)干湿循环效应促进了膨胀土裂隙发育,裂隙率增加导致渠坡变形增加和塑性区扩大,在膨胀土渠坡坡脚处变形显著。

Studying the development characteristics of cracks in expansive soil under the effect of dry-wet cycles is crucial for understanding the deformation and failure mechanism of expansive soil channel slopes.Addressing the current research limitations,an experiment on expansive soil crack development focusing solely on dry-wet cycles is conducted.Utilizing the block discrete element method based on the crack development pattern in expansive soil,a deformation analysis of expansive soil channel slopes is performed through programming.The study yields the following findings:(1)Water evaporation in expansive soil undergoes a transition from initial evaporation to stable evaporation,followed by deceleration rate evaporation and residual evaporation phases.(2)As the number of wet and dry cycles increases,the area ratio of expansive soil cracks gradually increases and then tends to stabilize.The total length of cracks increases progressively,while the average width of cracks continuously decreases and gradually stabilizes,and the angle between cracks transitions from T-shaped to Y-shaped.(3)The distribution of soil particles always develops towards a stable direction,the stress distribution between particles develops towards a more advantageous state,and the distribution of expansion and contraction cracks gradually stabilizes.(4)Applying the block discrete element method to analyze expansive soil slopes has successfully integrated the displacement and stress fields,taking into account cracks and hygroscopic expansion.(5)The wet-dry cycle effect accelerates crack development,with higher crack rates resulting in increased slope deformation,expansion of the plastic zone,and significant deformation at the base of expansive soil slopes.