Faure P, Coussot P
Laboratoire Navier, Université Paris-Est, Champs sur Marne, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 Sep;82(3 Pt 2):036303. doi: 10.1103/PhysRevE.82.036303. Epub 2010 Sep 2.
Drying experiments have been carried out with model soils made of different pastes filling granular packings. A detailed information concerning the time evolution of the water saturation distribution inside the sample was obtained from magnetic resonance imaging measurements. This study makes it possible to understand the physical origin of the drying characteristics of these materials. The drying curves exhibit a constant-rate period (CRP) and a falling-rate period (FRP) but the relative durations of these periods depend on the paste structure. With a kaolin suspension the CRP lasts down to very low water densities and is associated with a homogeneous drying of the paste throughout the sample. With a bentonite suspension the CRP is shorter and the drying in the FRP results from a complex process involving fractures progressing downward through the pasty matrix. With a gel the CRP period is even shorter and the drying in the FRP results from the progression of a dry front through the packing as a result of the shrinkage of the gel matrix. This provides an overview of the main possible processes at work when drying a soil as a function of its components along with some practical means for slowing down drying from soils.
已使用由填充颗粒填料的不同糊剂制成的模型土壤进行了干燥实验。通过磁共振成像测量获得了有关样品内部水饱和度分布随时间演变的详细信息。这项研究使得理解这些材料干燥特性的物理起源成为可能。干燥曲线呈现出恒速期（CRP）和降速期（FRP），但这些时期的相对持续时间取决于糊剂结构。对于高岭土悬浮液，恒速期一直持续到非常低的水密度，并且与整个样品中糊剂的均匀干燥相关。对于膨润土悬浮液，恒速期较短，降速期的干燥是一个复杂的过程，涉及裂缝向下穿过糊状基质。对于凝胶，恒速期更短，降速期的干燥是由于凝胶基质收缩导致干燥前沿穿过填料而产生的。这概述了干燥土壤时根据其成分起作用的主要可能过程，以及一些减缓土壤干燥的实际方法。
