1. School of Traffic Engineering, Guizhou Institute of Technology, Guiyang 550003;
2. School of Civil Engineering and Architecture, Beijing Jiaotong University, Beijing 100044;
3. College of Civil Engineering, Guizhou University, Guiyang 550025;
4. College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025
The vulnerability of the foundation of a factory building in Guizhou is due to the Alkali pollution, which originates the decrease of void ratio, specific weight, and plasticity index of the land. To study the transformation of shear strength of red clay, the authors design laboratory experiments combined with the pollution of the alkali concentration and the sources of the production process of Alumina. The facts of maintenance time and concentration of alkali liquor are also considered into the experiments. Within the help of technologies like scanning electron microscope(SEM),the results are concluded and supported by the raw data. Starting with the microstructure of the fracture surface of the red clay contaminated by alkali when the shear displacement is 4 mm, the fracture mode of the micro-pore and particle is analyzed qualitatively and quantitatively, and the fracture mode during the shear failure is explored. The achieved results suggest that in high NaOH solution shear strength are increased, most of the pores are inert pores, the direction of the pores is good, and the particles become longer. In the sources of the production process of Alumina, shear strength are the best. All most of the pores are inert pores, direction of the pores is the best, the particles become the longest. In low NaOH solution, shear strength are decreased, there are many macropores in the soil, the direction of pores is poor, and the particles are still in good roundness. It should be paid attention to in the project, which can provide some reference for the improvement of red clay polluted by alkali.