冻融对压实黄土工程地质特性影响的试验研究

Experimental Research on Impact of Freezing and Thawing on Geotechnical Properties of Compacted Loess

季节冻土区黄土路基经常遭受强烈的冻融循环作用,使得路基土体的水分重新分布、密度发生变化,严重的会导致路基发生较大变形而破坏,造成一定的经济损失和安全隐患。通过补水条件下的压实黄土冻融循环试验,研究冻融循环作用对压实黄土的水分分布、变形和干密度等工程地质特性的影响。试验结果表明：反复的冻融循环作用使得土样含水率增加,从底板到顶板土样含水率逐渐递增,且含水率增加幅度随冻融次数的增加而增加;土样在冻融循环初期冻胀变形大于融沉变形,总体变形显著增加,经过一定冻融循环次数后土样总体变形趋于稳定,冻融循环后期土样出现较小的沉降变形;冻融循环使得土样的干密度逐渐减小,冻融循环次数越多,其干密度减小幅度越大。研究成果对压实黄土路基病害形成机理及防治措施研究具有重要的科学意义。

The compacted loess subgrade in seasonally frozen ground regions are often subjected to strong freezing and thawing,which always lead to water redistribution and structural weakness in loess subgrade and then result in safety problem and economic loss.The impacts of freezing and thawing on deformation,water redistribution and dry density of compacted loess samples are studied by laboratory experiments in an open system based on water supply.The experiment results show that the freezing and thawing would make the water content of loess samples increased gradually from bottom to top,and this increase is proportional to the number of freezing and thawing cycles;the deformation of loess samples induced by frost heave is larger than that induced by thaw settlement at the first.So the whole deformation increases quickly,and then becomes steady after certain freezing and thawing cycles.Finally,there is small subsidence on loess samples at the end of freeze-thaw cycles.In addition,the dry density of compacted loess samples also is decreased gradually after freezing and thawing cycles,which are more apparent at the top of sample than at the bottom.