结构性吹填土压缩变形微观机理试验
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摘要
吹填土是一种人造土,具有大孔隙比、压缩性强、低强度等特点,其微观结构对土的力学性质有很大的影响,是一种强结构性土。通过分析不同轴向应力下压缩土样的微观SEM照片,探讨了孔隙微结构参数与轴向应力之间的关系,得出在吹填土压缩变形过程中存在屈服应力。在所受应力大于和小于屈服应力时,吹填土的压缩性存在差异,其微观表现为微结构参数在压缩过程中产生了突变,其根源是在压缩变形过程中,吹填土的微观结构产生了破坏。简要分析了结构性吹填土压缩变形微观机理。结果表明,吹填土的压缩过程分为孔隙中气体的压缩与水份的运移、团粒的相对滑移和结构破坏与新结构形成3个阶段。
The hydraulic fill is a kind of artificial soil,having such characteristics as large void proportion,strong compressibility,low strength.The indoor test result shows that the microstructure of hydraulic fill has a great in-fluence on it’s mechanics property,so it is a kind of strong structured soil.Through microstructure test,the SEM pictures of compression test soil sample under different axial stress are analyzed,and the relation between the void microstructure parameter and axial stress is studied,it is believed that the destroy stress exists during compress distortion.The compress character is different when the stress is larger or less than the destroy stress.The micro-cosmic proof is that the microstructure parameter changes suddenly,because the micro-structure is destroyed dur-ing compress distortion.At last the compression transforms mechanism of structured hydraulic fill is analyzed in brief,the result shows that the compressive process of hydraulic fill is thus divided into three stages:(a) the com-pression of gas in void and migration of the moisture content;(b) mutual slipping of the pellet,and(c) failure of soil structure and the formation of new structure.
The hydraulic fill is a kind of artificial soil,having such characteristics as large void proportion,strong compressibility,low strength.The indoor test result shows that the microstructure of hydraulic fill has a great in-fluence on it’s mechanics property,so it is a kind of strong structured soil.Through microstructure test,the SEM pictures of compression test soil sample under different axial stress are analyzed,and the relation between the void microstructure parameter and axial stress is studied,it is believed that the destroy stress exists during compress distortion.The compress character is different when the stress is larger or less than the destroy stress.The micro-cosmic proof is that the microstructure parameter changes suddenly,because the micro-structure is destroyed dur-ing compress distortion.At last the compression transforms mechanism of structured hydraulic fill is analyzed in brief,the result shows that the compressive process of hydraulic fill is thus divided into three stages:(a) the com-pression of gas in void and migration of the moisture content;(b) mutual slipping of the pellet,and(c) failure of soil structure and the formation of new structure.
引文
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[3]陈铁林,周成,沈珠江.结构性粘土压缩和剪切特性试验研究[J].岩土工程学报.2004,26(1):31-35.
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[5]齐吉琳,谢定义,石玉成.土结构性的研究方法及现状[J].西北地震学报,2001,23(1):99-103.
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