Drought-Induced Soil Desiccation Cracking Behavior With Consideration of Basal Friction and Layer Thickness
Drought-Induced Soil Desiccation Cracking Behavior With Consideration of Basal Friction and Layer Thickness
复制标题
考虑基底摩擦力和层厚度的干旱引起的土壤干燥开裂行为
DOI：
10.1029/2019wr026948
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发表时间：
2020
影响因子：
5.4
通讯作者：
Shi Bin
中科院分区：
文献类型：
--
作者：
Zeng Hao;Tang Chao-Sheng;Cheng Qing;Zhu Cheng;Yin Li-Yang;Shi Bin
随着全球气候变化的到来，干旱引起的土壤开裂问题备受关注。开裂过程加速了孔隙水的蒸发速率，降低了土体的保水能力，降低了土体的水力力学性能。基底摩擦和层厚是影响地下开裂的两个重要因素。为了探究其对干燥条件下土体的详细影响，我们在12个浆状土棒上进行了一系列的干燥试验，并选择了4种不同粗糙度的基材和3种不同的层厚。我们跟踪了不同样品的动态开裂过程，并采用非接触光学技术-数字图像相关技术对土壤颗粒的运动进行了研究。试验结果表明，地基条件和土层厚度的耦合效应对土体开裂行为起关键作用。底面粗糙的存在导致了底面和顶面干燥裂纹的产生和扩展。有些从底部开始的裂缝不会通过土壤剖面传播。随着土层厚度的增加，基底摩擦力对土顶面收缩的影响减弱，但作用于基底的摩擦力增大，导致底部裂纹萌生增多。数字图像相关结果进一步揭示了底表面萌生并垂直向上扩展的裂缝以拉应力为主，而斜向上扩展的裂缝则以剪应力和拉应力共同作用为主。
Drought-induced cracking of soils is of great concern with the advent of global climate change. The cracking process accelerates the evaporation rate of pore water, lowers the water retention capacity, and degrades the hydraulic-mechanical properties of soils. Basal friction and layer thickness are two important aspects affecting the subsurface cracking. To explore their detailed effects on soils under drying, we conduct a series of desiccation tests on twelve slurry soil bars and select four types of base materials with different roughness levels and three kinds of layer thicknesses. We track the dynamic cracking process in various samples and adopt the noncontact optical technique-digital image correlation-for the motion of soil particles. Experimental results validate that the coupled effects of basal conditions and soil layer thickness play a key role in governing the soil cracking behavior. The presence of rough bottom surface induces the onset and propagation of desiccation cracks at both top and bottom surfaces. Some of the cracks initiated at the bottom do not propagate through the soil profile. Increasing layer thickness weakens the effect of basal friction on the soil top surface shrinkage but increases the frictional force acting on the base and results in more crack initiations at the bottom. The digital image correlation results further reveal that cracks initiated on the bottom surface and propagated upward vertically are dominated by tensile stresses, while those propagated upward obliquely are dominated by the joint action of shear and tensile stresses.