基于热力学模型的粉砂土改良膨胀土孔隙结构分形模型

为了减少膨胀土对土木工程的危害，降低工程的经济损失。对粉砂土改良膨胀土进行试验研究，通过对粉砂土掺量为0、10%、20%、30%、40%的膨胀土进行压汞试验，测得进汞压力同累计进汞量关系、孔径同累计孔隙体积关系、孔径与进汞增量关系；并选取热力学模型表征改良膨胀土孔隙结构特征，获取改良膨胀土孔隙分形维数。结果表明：掺加粉砂土会使得土体孔隙有所增加，孔隙类型发生了变化，随着粉砂土掺量的增加，孔径在1～1×10⁴ nm降低，在1×10⁴～1×10⁶ nm升高；基于热力学模型分析改良膨胀土孔隙分形特征时，分形维数2.410 83～2.580 32变化，线性相关系数在0.984 95～0.997 7,表明热力学模型能较好地表征粉砂土改良膨胀土孔隙的结构特征。

Fractal model of pore structure of expansive soil improved by silty sand based on thermodynamic model

In order to reduce the harm of expansive soil to civil engineering and reduce the economic loss of engineering. The experimental study on the expansive soil improved by silty sand was carried out. Through the mercury injection test of expansive soil with 0%, 10%, 20%, 30% and 40% silty sand, the relationship between mercury inlet pressure and accumulated mercury inlet, the relationship between pore diameter and accumulated pore volume, and the relationship between pore diameter and mercury inlet increment were measured. The thermodynamic model is selected to characterize the pore structure characteristics of the improved expansive soil, and the pore fractal dimension of the improved expansive soil is obtained. The results show that adding silty sand will increase the porosity of soil and change the pore type. With the increase of silty sand content, the proportion of pore size decreases from 100 nm to 104 nm and increases from 104 nm to 106 nm. When analyzing the pore fractal characteristics of improved expansive soil based on thermodynamic model, the fractal dimension varies from 2.41083 to 2.58032, and the linear correlation coefficient ranges from 0.98495 to 0.9977, which indicates that the thermodynamic model can better characterize the pore structure characteristics of silty sand improved expansive soil.