Cement flow in interaction rock fractures and its corresponding new construction process in slope engineering

Cement as the main grouting material is usually used in the plugging and reinforcement of tunnels and rock slopes. The flow and diffusion mechanism of grout in fractures plays a key role in guiding the design. Based on the geological fractures and Navier-Stoke equations, the coupling model of cement flow considering the mutual interaction between fractures is established. The fracture-fracture perturbation factor (FPF) and perturbation intensity factor (PIF) are defined. Considering the coupling effect under the diversion, the disturbance in the cement flow and the grouting parameters are discussed with a case of XW coal mine as background. The results show that, in cement diffusion, the existing fractures can weaken the flow capacity of cement in another fracture, resulting in a power function decline of pressure drop, velocity and its related FPF with coefficient of <-2. FPFs are symmetrical and always less than 1 hindering the cement diffusion. The influence of wide fracture on narrow one is larger, and its degree is further enhanced with the increase of the aperture ratio. The cement always diffuses with wide fracture as the main flow path. The FPF and matrix deformation can change the threshold value of grouting parameters for the conventional design. Based on the flow mechanism of cement slurry, the problems of poor grouting effect, slurry leakage, and dilation in different layers of rock slope in XW mine are revealed. The grouting parameters and proportion of slurry materials are optimized based on the disturbance factor. The grouting method of multi holes and strata injection in rock slope (RS-MHSI) is improved correspondingly. The conclusions of this study can be helpful to better understand the flow mechanism of slurry in geological fractures and to optimize the grouting parameters in the field.

Automated summary

The study is based on the flow mechanism of cement slurry in geological fractures, enhancing the accuracy of traditional grouting design and optimizing the grouting parameters and slurry materials ratios; the case study revealed that existing fractures can weaken the flow capacity of cement in another fracture, affecting the diffusion of cement, with wider fractures having a greater impact on narrower fractures.