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离子型稳固剂对膨胀土缩-裂进程的调控机理研究(2016-2019)

作者: 来源: 日期:2017-4-24 15:46:13 人气:27 评论:0 标签:

 

项目来源:国家自然科学基金(面上项目)

 

项目简介:

    膨胀土在干燥环境下极易收缩龟裂,对土体工程性质产生重要不利影响,本项目探索一种新型离子稳固剂对膨胀土缩-裂性状的抑制过程及调控机理。以两种典型强膨胀土为研究对象,立足于”缩-裂”进程中水分迁出这一主线,首先实验建立“水汽等温脱附-脱湿热区间-水分子结构振动光谱分析”的水分迁出形态界定量化方法,在此基础上,开展失水-收缩-缩裂动态关联特征分析,从水分迁出-吸力发展-孔隙结构演化多角度探讨固化剂对“缩-裂”发生发展的影响机制;从干燥过程中土/水作用的微细观层面,构建“晶层表面-吸附阳离子-溶质渗透-静电场力-粘土单片组构”多因素耦合的微观缩应力模型,结合抗拉强度测试,提出改性土起裂判据模型,从而揭示离子稳固剂对膨胀土缩-裂性状改变的本质机理。项目的成功实施可为膨胀土“裂隙性”的控制方法研究提供理论依据和有益借鉴,可有力推动膨胀土地区工程建设及特殊土改良理论发展,具有重要科学价值和广阔应用前景。

 

Expansive soils shrink and crack easily in dry environment, which in turn has an adverse impact on engineering properties of soil mass. The aim of this project is to explore the effect of a novel ionic soil stabilizer (ISS. abbreviation) on the shrinkage-cracking process of expansive soil.In this proposed project, a two different type of strong expansive soil will be studied. A combined method to quantitatively describe the dehydration state of expansive soil was firstly proposed based on experimental analysis of water vapor desorption isotherm,dehydration thermodynamics and water structure vibration spectrum. Based on such method, analysis of dynamic connection between dehydration,shrinkage and desiccation cracking was performed to investigate the influence of ISS on the process of shrinkage-cracking of expansive soil in terms of dehydration behavior,suction and pore structure evolution. From a perspective of micro-interaction between soil and water, a micro-shrink stress model of modified soil is expected to be set up, which takes fully account of the coupling effect of “clay layer surface property-exchangeable cation-solute osmosis-electrostatic field force-clay particle unit fabric” on the shrinkage potential. Combining the micro-shrink stress model and macro-tensile strength behavior, a crack criterion model is finally proposed to reveal the mechanism of ISS inhibiting the shrinkage and desiccation cracking. Overall, these project achievements would provide theoretical basis and useful reference for controlling crack behavior of expansive soil. It would also provide a strong promotion to the engineering construction in expansive soil area and problematic soil stabilization theory. Therefore, this project possesses enormous academic value and broad prospect in engineering applications.

 

分流湿度控制条件下的收缩试验系统

自主研制的土体拉伸仪示意图及样机照片

                      径向收缩率失水过程变化          改性前后膨胀土缩裂状态变化

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