膨胀土一次性浸水膨胀3参数时程模型

Three-parameter Model for Expansive Deformation Process of Expansive Soil

膨胀土浸水后的膨胀时程曲线是膨胀土浸水变形力学行为的基本问题.引入膨胀半衰期的概念,建立了包括初始膨胀速率、最终膨胀量的膨胀时程模型的数学特征方程,并依此揭示了双曲线时程模型的缺陷.微观膨胀机理分析表明,浸水后膨胀变形的过程对应为土中原有的化学键断裂、新的氢键生成并伴随晶格水膜增厚的过程.根据机理分析和能量耗散假定,建立了基于控制微分方程的3参数膨胀时程模型.严格证明了双曲线模型及其数学特征方程均是对应3参数模型的特例.两个实例计算表明该模型具有很高的精确性和适用性.

Expansive deformation process plays an important role in studying expansive soil mechanical behavior after inundation. Addition to initial expansive rate and final expansive deformation, half-value time of expansive deformation process was employed to construct the mathematical property set of deformation-time model. The deficiency of hyperbolic model for expansive deformation was pointed out by the mathematical property set. Micro-analysis showed that the expansive process was resulted from the increased thickness of water film around soil particle induced by the original chemical bonds breaking and new hydrogen bonds developing. According to mechanism analysis and some postulates, the governing differential equation for expansive deformation process was obtained, and a 3-parameter model for expansive deformation process was established. Mathematical proof showed that the hyperbolic model and its mathematic property set were corresponding degraded expressions of the new derived model, respectively. The derived model satisfies the mechanical behavior of the expansive deformation process, and good agreements between the new model calculated results and two field tests have been found.