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非饱和膨胀土的脱湿状态对土中水分散失速率影响较大,不同的脱湿速率又会使膨胀土呈现不同的工程性状。通过控制恒温恒湿箱的温湿度工作参数,设置不同的脱湿环境制备土样,进行土工试验,深入认识脱湿状态对膨胀土膨胀变形和抗剪强度的影响。将饱和土样脱湿到设定的不同含水率,进行有荷载膨胀率试验,结果表明:在相对湿度越大的环境下,脱湿速率越小,土体膨胀率越大;起始含水率和上部荷载越小,土体膨胀变形越大。将不同起始含水率的土样膨胀完全后放入直剪仪,进行固结直剪试验,结果表明:脱湿到不同含水率的试样,脱湿速率越小,土体越密实膨胀后的抗剪强度越大;上部荷载存在可提高土体的抗剪强度,起始含水率越小上部荷载越大土样的抗剪强度越高。研究结果可为大气作用下膨胀土边坡的防护设计提供参考,有助于对自然气候环境下膨胀土边坡的灾变进行预警,并可优化膨胀土边坡的施工方案。
The desorption state of unsaturated expansive soil has a great influence on the rate of soil water loss. The different desorption rate will make the expansive soil show different engineering characters. By controlling the temperature and humidity operating parameters of the constant temperature and humidity box, different dehumidification environments were set up to prepare the soil samples for geotechnical tests. The effects of the dehumidification conditions on the expansion and deformation and the shear strength of the expansive soil were thoroughly understood. The saturated soil samples were dehumidified to set the different moisture content, the load expansion test was carried out. The results showed that the smaller the dehumidification rate, the larger the expansion rate of the soil under the environment of higher relative humidity. The initial moisture content And the smaller the upper load, the greater the deformation of soil expansion. The different initial moisture content of soil samples were completely expanded into the direct shear instrument, the consolidation shear test results show that: dehumidification to different moisture content of the sample, the smaller the rate of dehumidification, the more dense soil after expansion The higher the shear strength of soil samples, the higher the upper load is, the higher the shear strength of soil samples is. The results can provide reference for the design of the protective design of expansive soil slope under the action of atmosphere, which can be used to predict the disaster of expansive soil slope in natural climatic environment and to optimize the construction scheme of expansive soil slope.