红石河水库枢纽区膨胀土饱和度对抗剪强度的影响

膨胀土遇水膨胀失水干缩,对工程构筑物危害巨大,以云南省瑞丽市畹町经济开发区红石河水库枢纽区膨胀土为试样土,通过一系列不同饱和度的原状土和重塑土直剪试验发现,随着饱和度的增大,膨胀土的剪切强度、内摩擦角和粘聚力均逐渐降低,但剪切强度和粘聚力的降低趋势较内摩擦角更加明显,且当饱和度逐渐增大时,内摩擦角的降低趋势逐渐减缓最终趋于稳定,同时原状土对外部因素的敏感性低于重塑土。土体的力学特性是土体内的矿物种类、矿物含量、水分及土体内部结构等综合作用的结果,并据此提出了一个考虑水分和土体自身性质的剪切强度计算模型,对比计算结果与试验结果,验证了该模型的有效性。研究成果可为类似工程提供参考依据。

Impact of Water Saturation of Expansive Soil in Hongshihe Reservoir Junction Area on Direct Shear Strength

Expansive soil will cause great harm to engineering structures when it meets water.In this paper,expansive soil obtained from Hongshihe hydro project area in Wanding Economic Development Zone of Ruili City in Yunnan Province is taken as the soil sample.Through a series direct shear tests of reconstituted samples and natural soil samples with different water saturation,it is found that with the increase of water saturation,the shear strength,internal friction angle and cohesive force of expansive soil decrease gradually,but the downward trend of shear strength and cohesive force is more obvious than that of the internal friction angle;when the saturation increases gradually,the downward trend of internal friction angle is gradually slow down and eventually stabilized;at the same time,natural soil samples’ sensitivity to external factors is less than the undisturbed soil.The mechanical properties of soil are determined by the combination of types of mineral,mineral content,soil moisture and the soil internal structure.Thus,a shear strength calculation model is proposed considering water saturation and soil properties.The effectiveness of the model is verified by comparing the calculation results with the experimental results.The research results can provide a basis for similar projects.