Model test study on microstructure characteristics of pile-soil interface of press-grouting pile

To explore the microstructure characteristics of the pile-soil interface of bored press-grouting pile, the laboratory orthogonal model test method was used to make qualitative and quantitative analysis on the scanning electron microscopy (SEM) images of the pore structure of the pile-soil interface under different grouting pressure, water-cement ratio, dry density and moisture content of soil. The burr phenomenon of pile-soil interface and the variation law of pore microstructure parameters with experimental factors were studied. Research results show that the burr phenomenon exists objectively and is caused by the interaction of pile and soil. The influence of grouting pressure on the test is the most significant, followed by the dry density, and the influence of water-cement ratio and moisture content is less. Properly increasing the pressure of grouting and the dry density of soil can enhance the filling effect of cement slurry and its three-dimensional network hydration products, which can also reduce the porosity and pore number of soil at the pile-soil interface, weaken the orientation of pores and increase the complexity of microstructure, strengthening the pile-soil interaction effect and integrity and increasing the pile shaft resistance finally. © 2021, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.