不同浸水时间黄河堤防土体强度特性试验研究

 土体抗剪强度参数在堤防边坡稳定性分析中是十分重要的，现行堤防设计规范没有涉及堤防土体浸水后强度特性变化情况。考虑黄河下游堤防洪水历史和堤防临水状况，进行堤身土体的固结压缩、直接快剪和不固结不排水三轴试验，特别是土样浸水后的强度特性试验，研究堤防土体浸水后强度指标的变化及其机制。试验结果表明：黄河下游堤防堤身土体浸水5 d后黏土压缩系数增大1.46倍，黏聚力最大降低72.6%；粉土压缩系数增大0.64倍，黏聚力最大降低62.8%，而2种土的内摩擦角变化较小。试验结果为黄河下游堤防标准化设计和堤坡稳定性分析提供了科学依据，并对黄河堤防的管理提出了建议。

TEST STUDY OF SOIL STRENGTH WITH DIFFERENT SOAKED PERIODS OF EMBANKMENT OF YELLOW RIVER

The soil shear strength is important to analyze the stability of embankment and slope. A series of soil mechanics tests(compression test，quick shear test and unconsolidated-undrained(UU) test are carried out using levee soils of downstream embankment of Yellow River，especially the strength test of the soils with different soaked periods. The change and reducing degrees of strength parameters of clay and soaked silt，and the reasons of strength change and the effect on the stability of embankment are discussed. Because of soaked soil，the compression coefficient of soil obviously increases and the modulus of compression obviously decreases. The compression coefficient of clay samples soaked for 5 days increases 1.46 times at the most than that without being soaked，and 0.64 times for silt samples. At the same time，for the soaked soil，the deformation of clay is geaterer than that of the silt. The conclusion of quick shear test is that the cohesive of clay reduces by 72.6%，silt by 62.8% and internal friction angle changes a little soaked for 5 days because the action of water to soil only destroy the sequence and cement of soil grains，but the soil grain component is not varied. The results of UU test is complex. For the clay samples，c and j decrease quickly with soaked sample，but the time effect of soaked clay is small. However，for the silt，the longer the time that the sample is soaked，the lower the strength of the silt is. It will be the reference to the design and stability analysis of embankment，and the results will be afforded for the management of the Yellow River embankment operation.