反复冻融条件下粉砂土动力学参数试验研究  

Experimental study of dynamic parameters of silty soil subjected to repeated freeze-thaw

作　　者：严晗[1,2] 王天亮[3,4] 刘建坤[1] 王扬[3,4] 

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]中铁建工集团西北分公司,西安710119 [3]石家庄铁道大学土木工程学院,石家庄050043 [4]石家庄铁道大学道路与铁道工程安全保障省部共建教育部重点实验室,石家庄050043

出　　处：《岩土力学》2014年第3期683-688,共6页Rock and Soil Mechanics

基　　金：国家重点基础研究发展计划973(No.2012CB026104);国家自然科学基金(No.51208320);河北省自然科学基金(No.E2013210040)

摘　　要：在大量冻融试验和动三轴试验的基础上,深入研究和分析了经历多次冻融循环后粉砂土动模量和阻尼比的变化规律。研究结果表明:同一动应变水平下,动应力大小与冻融次数、含水率呈负相关性,而与围压、加载频率、压实度呈正相关性;粉砂土的动应力-动应变关系存在明显的非线性,且随动应变水平的提高,动模量成倍减小,而阻尼比则成倍增大;随冻融次数的增加,动模量降低而阻尼比则增大,且经历6次冻融后均趋于稳定,建议将6次冻融后的力学特性作为设计与计算指标;围压和压实度的提高有效增强了土颗粒之间的骨架作用,动模量随围压和压实度的增减而增减,阻尼比则随围压和压实度的增加而降低;含水率的变化对阻尼比的影响不大,而当土样达到饱和状态时,动模量成倍降低;加载频率对阻尼比的影响较大,并随频率的提高而迅速降低。Based on amount of freeze-thaw tests and dynamic triaxial tests, the dynamic modulus and damping ratio properties of silty soil subjected to repeated freeze-thaw cycles were deeply researched and analyzed. The tests results are drawn as follows：At the same dynamic strain level, the relationships of dynamic stress and freeze-thaw cycles, water content present negative correlation, and the relationships of dynamic stress and confining pressure, frequency, compactness present positive correlation. The curves of dynamic stress vs. dynamic strain obviously present nonlinear relationship; and the dynamic modulus double decreases while the damping ratio double increases with the increasing of dynamic strain. The dynamic modulus sharply decreases while the damping ratio increases with the increasing of freeze-thaw cycles; and then the changes level off after 6 freeze-thaw cycles; while the mechanical properties after 6 freeze-thaw cycles are suggested for designing and calculating indexes. The soil particles contact area is improved by the increasing of confining pressure and compactness; and the dynamic modulus increases while the damping ratio decreases with the increasing of confining pressure and compactness. It is found that water content less affects damping ratio, but the dynamic modulus double decreases when the silty soil reaches saturation condition. The frequency is an important factor affecting on damping ratio, and damping ratio sharply decreases as the frequency increases.

关 键 词：冻融循环 粉砂土 动三轴试验 动模量 阻尼比 

分 类 号：TU411.8[建筑科学—岩土工程]