兰州大学机构库 >土木工程与力学学院
粉煤灰改良饱和黄土的抗液化强度和特性研究
Alternative TitleResearch on the liquefaction resistance and characteristics of saturated loess improved by fly ash
高中南
Thesis Advisor周仲华 ; 王峻
2018-06-06
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword粉煤灰 黄土 动本构关系 动孔隙水压力 固化机制
Abstract

以经济、环保改良处理来减轻饱和黄土地基液化震害为目的,通过制备不同粉煤灰掺量的改良黄土进行动三轴试验,研究了粉煤灰改良饱和黄土的动本构关系以及动应力、动应变和动孔隙水压力随振次变化特征。比较了不同配比饱和改良黄土初始动弹性模量、最大动应力幅、阻尼比等动力特性参数之间的关系。分析了粉煤灰掺量对饱和改良黄土液化应力比、动残余变形和动孔隙水压力的影响规律。并结合微结构试验与XRD测试结果,探讨了粉煤灰改良饱和黄土抗液化的物理化学机制。结果表明:不同配比粉煤灰改良饱和黄土动本构关系遵从双曲线模型。初始动弹性模量在粉煤灰掺量20%时达到最大值,粉煤灰掺入量增加引起最大动应力幅随同步上升,阻尼比相应降低。粉煤灰掺入量超过25%后,饱和改良黄土的动弹性模量与阻尼比随动应变增大变化极为缓慢。粉煤灰掺量对饱和改良黄土的液化应力比、动应变和动孔隙水压力均具有较为显著的影响。随着粉煤灰掺量的增加,饱和改良黄土的液化应力比持续增加,且当粉煤灰掺量达到15%后,继续增加粉煤灰掺量时改良黄土的液化应力比增加显著。饱和改良黄土的动应变和动孔隙水压力均随着粉煤灰掺量的增加而减小;粉煤灰掺量达到25%后,饱和改良黄土不液化。粉煤灰改良饱和黄土的SEM细观结构试验照片中呈现大量的圆球状、粒状粉煤灰颗粒和絮凝状胶结物,表明粉煤灰改良饱和黄土抗液化的物理化学机制主要包括粉煤灰的水化作用、胶体生成物和颗粒的填隙作用和粉煤灰对游离水的吸附作用。

Other Abstract

For the purpose of economic and environmental improvement of the seismic liquefaction damage on saturated loess foundation, the dynamic constitutive relation of saturated fly ash improved loess is discussed, and the variation characteristics of its dynamic stress, dynamic strain, dynamic pore water pressure with vibration times are analyzed through dynamic triaxial tests on the improved loess with different fly ash dosages. The relationship among the initial dynamic elastic modulus, maximum dynamic stress amplitude, and damping ratio of the saturated modified loess with different fly ash dosages were compared. Then the influence law of fly ash dosage on the liquefaction stress ratio, dynamic residual deformation, and dynamic pore water pressure of the improved loess is analyzed. Combined with the micro structural test and XRD test results, the physical-chemical anti-liquefaction mechanism of saturated loess improved by fly ash is also discussed in this study. The results show that the dynamic constitutive relation of the saturated modified loess with different fly ash dosages obeys the hyperbolic model. The maximum initial dynamic elastic modulus appears when the dosage of fly ash is 20%. With the increase of fly ash dosage, the maximum dynamic stress amplitude increases, but the damping ratio decreases correspondingly. When the fly ash content is more than 25%, the change of dynamic elastic modulus and damping ratio of saturated modified loess with the increase of dynamic strain becomes very slow. The dosage of fly ash has significant influence on the liquefaction stress ratio, dynamic strain, and dynamic pore water pressure of the improved loess. With the increase in the dosages of fly ash, the liquefaction stress ratio of the improved loess continues to grow; when the dosage reaches to 15%, the liquefaction stress ratio will obviously increase if the dosage continues to increase. The dynamic strain and dynamic pore water pressure of the improved loess increase with the decrease of fly ash dosage; after the dosage reaches to 25%, the saturated improved loess will not be liquefied. The microscopic test results by using scanning electron microscope (SEM) indicate that the physical-chemical anti-liquefaction mechanism of saturated loess improved by fly ash mainly includes the hydration process of fly ash, filling effect of colloid product and particles, and adsorption of free water by fly ash.

URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226532
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
高中南. 粉煤灰改良饱和黄土的抗液化强度和特性研究[D]. 兰州. 兰州大学,2018.
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