Using lignin for soil stabilization is one of the effective measures for lignin disposal. In order to study the effect of lim-lignin on stabilizing clay, a set of resonance column tests was conducted on clay stabilized by lime-lignin. The effects of confining pressure and lime-lignin content on the dynamic shear modulus characteristics of the stabilized soil were analyzed. Based on the relative structural degree method, a characterization model for the maximum dynamic shear modulus of the stabilized soil was proposed. The results show that the maximum dynamic shear modulus and dynamic shear modulus ratio of clay stabilized by lime-lignin increase with the increase of confining pressure. The maximum dynamic shear modulus and dynamic shear modulus ratio of 4% lime +4% lignin stabilized clay are the highest. Under the confining pressure of 300 kPa, the maximum dynamic shear modulus of 4% lime +4% lignin stabilized clay is 17.3% higher than that of 8% lime stabilized clay and 185.4% higher than that of pure clay. Based on shear strength parameters, the relative structural degree of stabilized soil is calculated and the relative structural degree of 4% lime +4% lignin stabilized clay is the highest. On the basis of Hardin formula, a characterization model of maximum shear modulus is established by introducing the relative structural degree. The model has good accuracy and can provide a basis for evaluating the dynamic shear modulus of clay stabilized by lime-lignin.

To study the shear strength characteristics of unsaturated rubber silt mixtures, a series of direct shear tests was conducted on the rubber silt mixtures with different rubber particle contents and water contents. Based on the particle contact state theory, the meso contact mode of rubber silt mixtures was constructed, and the calculation method of rubber silt mixtures skeleton void ratio based on different rubber content was obtained. The test results show that the shear strength of rubber silt mixtures decreases with the increase of skeleton void ratio at a low water content, while the strength of rubber silt mixtures increases with the increase of skeleton void ratio at a high water content. Based on the soil-water characteristic curve of rubber silt mixtures, the corresponding relationship between matrix suction and water content is obtained. The shear strength of rubber silt mixtures increases with the increase of matrix suction at a low skeleton void ratio, and it exhibits decrease first and then increase with the increase of matrix suction at a high skeleton void ratio. Based on the influence of skeleton void ratio and water content on internal friction angle and cohesion, the shear strength development mechanism of unsaturated rubber silt mixtures was proposed, and the prediction formula of shear strength was established. The research results can provide theoretical support for the actual design and construction of rubber silt mixtures.