冻融循环作用下含水率对粗颗粒填料水分迁移影响的宏细观试验研究北大核心CSCD

冻融循环作用和初始含水率是影响粗颗粒填料水分迁移特征和冻胀融沉变形的两个主要因素。为明确冻融循环作用下,不同初始含水率粗颗粒填料的水分迁移特征及细观机制,采用荧光素为追踪剂,以CT细观机理观测为研究手段,开展了不同初始含水率条件下粗颗粒填料的一系列冻融循环试验,探究了温度场和冻深变化、水分迁移图像、补水量变化、最终含水率分布及CT值变化规律等。试验结果表明,冻深基本随冻融循环的次数增加不断加深,初始含水率越大,不同冻融循环作用下冻深的变化越稳定。外界补水量和液态水迁移高度与初始含水率呈负相关。CT扫描结果分析表明,经历多次冻融循环后,试样中的水分迁移导致土体孔隙结构及颗粒构造发生变化,试样的密度普遍增加,孔隙率以减小为主,进而导致土体发生相应变形。

Macro-micro experimental investigation of the initial water content influence on water migration of coarse-grained soil subjected to freezing and thawing

Freezing-thawing and initial water content are the main factors to influence the water migration characteristics， frost heaving and thaw settlement of coarse-grained soil. To clarify the water migration characteristics and micro mechanics of coarse-grained soil with different initial water content under freezing and thawing， fluorescein is taken as the tracer and computerized tomography （CT） is adopted as the micro mechanics method， a series of experiments were carried out to study the temperature field， frost depth development， water supply， final water distribution， water migration images and CT values of the coarse-grained soils with different initial water content under freezing and thawing. Results indicate that the frost depth increase continually with the increasing numbers of the freezing-thawing cycles basically. The external water supply and the migration height of the liquid water are negatively correlated with the initial water content. CT scanning results indicate that after several times of freezing-thawing， the water migration results in the changes of the soil pore and particle structure， then the changes of the samples density increase and the porosity decreases， then the related deformation occurs in the soil.