不均匀收缩方式对膨胀土工程性状影响试验研究

通过控制恒温恒湿箱的温湿度工作参数，改变膨胀土试样的蒸发路径，实现饱和膨胀土在不同脱湿速率下的不均匀收缩，结合有荷膨胀率试验和直接剪切试验，研究膨胀土不均匀收缩方式下胀缩特性和强度特性。试验结果表明，脱湿速率越小，膨胀土的胀缩性越大，剪切强度越高；对比不同收缩方式，均匀收缩下膨胀土的收缩与膨胀变形和剪切强度均大于不均匀收缩下的收缩与膨胀变形和剪切强度。造成这些差异的主要原因是不均匀收缩试验中水分蒸发的路径不同，沿深度方向的含水率不同，基质吸力不同，引起的应变也不同，这种不均匀性改变了原有膨胀土的均一性，限制了膨胀土胀缩特性和强度特性的发挥。

Experimental study of impact of non-uniform shrinkage on engineering behaviors of expansive soil

Through adjusting the working parameters of temperature and humidity in the constant temperature and humidity equipments and changing the expansive soil evaporation path, the non-uniform shrinkage test of saturated expansive soil under different drying rates is achieved, which combined with swelling test and direct shear test to research the expansion and contraction characteristics and strength properties of expansive soil under non-uniform shrinkage test. The experimental results indicate that the smaller the drying rates is, the larger the deformation of the expansive soil and the higher of the shear strength is. The contraction, shrinkage deformation and shear strength of the expansive soil under uniform shrinkage condition are larger than non-uniform shrinkage condition. The main reason for these differences is the different paths of evaporation in non-uniform shrinkage test, which leads to different water contents along the depth direction, different matrix suction and different strain. The non-uniform shrinkage changes the homogeneity of expansive soil and limits the expansion and contraction characteristics and strength properties of expansive soil.