极端干旱中压实粘土干缩裂缝演变分析与模拟

Evolution and Calculation Analysis of Shrinkage Cracks in Compacted Clay Under Extreme Drought Conditions

极端干旱导致粘土体产生干缩裂缝,对土的基本力学性质产生很大影响,目前对干缩裂缝的研究多基于泥浆试样,而工程中面对的大多为压实填筑土体。为此,通过理论分析,考虑土体宏观情况下压实粘土的收缩过程,在残余收缩阶段,通过土样模型试验,依靠数字图像处理技术获取受旱过程中裂缝演变情况,展开定量统计分析,发现土体干密度限制裂缝最大发育程度,而土体实时含水率控制裂缝发展速度,裂缝最大深度、宽度与土体干密度呈负相关关系。基于土体内部收缩应力变化,提出了压实粘土体干缩裂缝扩展深度、宽度计算模型,比较裂缝计算宽度与土样试验结果,发现受边界条件影响,试验中裂缝宽度小于计算值。研究结果对揭示压实粘土裂缝演变规律具有促进作用,亦对开展干缩裂缝防治具有一定的指导意义。

The shrinkage cracks in the soil caused by the extreme drought will have a great impact on the basic mechanical properties of the soil. At present, the research on dry shrinkage cracks is mostly based on mud samples while the engineering is mostly faced with compacted filling soil. Through soil sample model test, the evolution of cracks in the process of drought was obtained by digital image processing technology, and quantitative statistical analysis was carried out. It is found that the dry density of soil limits the maximum development degree of cracks, while the real-time moisture content of soil controls the development speed of cracks. Based on the change of internal shrinkage stress, a model for calculating the expansion depth and width of dry shrinkage crack of compacted clay is proposed. The width of crack calculation is less than the calculated value due to the influence of boundary conditions. The results of the study can promote the evolution of compacted clay fractures and have certain guiding significance for the prevention and control of dry shrinkage cracks.