Propagation Analysis of Polymer Grout in Vertical Fractures: An Experimental and Numerical Study

The use of non-aqueous reactive polymer grouting is a proven technique for preventing gravity erosion in Pisha sandstone through the filling of vertical fracture. However, the diffusion behavior of the polymer grout within vertical fractures remains unclear and requires further investigation for effective grouting design. This study conducts laboratory experiments to examine the effects of grouting quantity on the spread pattern, diffusion distance, and pressure distribution of polymer grout within a visual vertical fracture. The maximum pressure is 6.25 kPa for a grouting quantity of 120 g, 7.5 kPa for 227 g, and reaches about 9.4 kPa for a quantity of 350 g. A numerical model, incorporating time-dependent density and viscosity, is then developed and validated using experimental results. Finally, the influence of initial viscosity 0.05 Pa·s, 0.1 Pa·s, and 0.5 Pa·s on the flow pattern of polymer grout within the vertical fracture is analyzed. The results show that initially gravity causes a dominant downward flow of polymer grout in a vertical fracture. However, as the grout expands due to the chemical reaction, it propagates in all directions. Furthermore, the gravity causing the dominant downward flow of polymer grout decreases with increasing initial viscosity, and the diffusion distance increases in the horizonal direction but decreases in the vertical direction. On this basis, suggestions for optimal grouting hole arrangement are provided to enhance grouting design.