基于核磁共振的冻融循环作用下重塑黄土强度变化规律  

Variation Law of Remolded Loess Strength under the Action of Freeze-thaw Cycle Based on Nuclear Magnetic Resonance

作　　者：马宝芬 杨更社[1] 田俊峰[1] 潘振兴 刘慧[1] MA Bao-fen;YANG Geng-she;TIAN Jun-feng;PAN Zhen-xing;LIU Hui(School of Architecture and Civil Engineering,Xi′an University of Science and Technology,Xi′an,710054,China)

机构地区：[1]西安科技大学建筑与土木工程学院

出　　处：《科学技术与工程》2019年第24期318-323,共6页Science Technology and Engineering

基　　金：国家自然科学基金(41272340,41172262,41672305,41702339)资助

摘　　要：为了研究冻融循环对重塑黄土抗剪强度的影响,分宏观及微观两个方面来进行试验研究。在宏观层面上,通过对不同冻融循环次数下、不同含水率的土样的进行三轴压缩试验,得到相应的应力-应变曲线;从微观层面上,利用核磁共振(nuclear magnetic resonance,NMR)成像分析仪,测得土样在不同冻融循环次数下的T 2时间分布曲线。结果表明:未冻融状态下,含水率为13%的土样其应力应变曲线为应变软化型;随含水率逐渐增加其应力-应变曲线由应变软化型变为应变硬化型。随冻融循环次数的增加,含水率为13%的土样其应力-应变曲线依旧为应变软化型;但抗剪强度逐渐降低,而随含水率逐渐增加,土样应力-应变曲线由应变硬化型有逐渐向应变软化型过渡的趋势;且含水率越高曲线软化趋势越明显。In order to study on the effect of freeze-thaw cycle on the shear strength of remolded loess,experimental research from both macro and micro aspects was conducted.On the macro level.The soil sample was subjected to a triaxial compression test with different water content and different freeze-thaw cycles.Then the respective stress-strain curves were obtained.On the micro level.Nuclear magnetic resonance analyzers were being utilized.The T2 time distribution curve of soil samples under different freeze-thaw cycles was measured.The results show that the stress-strain curve of the soil sample with a water content of 13%is strain-softening in the unfrozen-thawed state.With the increase of water content,the stress-strain curve changes from strain softening to strain hardening.With the increase of the number of freeze-thaw cycles,the stress-strain curve of soil samples with a water content of 13%is still strain-softening,but the shear strength is gradually reduced.As the water content increases,the stress-strain curve of the soil sample gradually changes from the strain hardening type to the strain softening type.Moreover,the higher the water content,the more obvious the softening tendency of the curve.

关 键 词：抗剪强度 重塑黄土 核磁共振 T2时间分布曲线 

分 类 号：TU411[建筑科学—岩土工程]