Laboratory Study on Diffusion and Migration of Grout in Rock Mass Fracture Network
Publication: International Journal of Geomechanics
Volume 21, Issue 1
Abstract
The flow process of grout in a rock mass fracture network is an important part to judge the effect of grouting in engineering. Till date, little research has been done on the diffusion and migration pattern of grout in a random fracture network. Based on this, herein, a visualized fracture grouting test system with constant pressure was developed, consisting of pressure supply equipment, constant-pressure pulping equipment, fracture simulation equipment, and monitoring equipment. The system can simulate the flow process of the fracture network under the effect of various parameters such as the grouting pressure, grout characteristics, and fracture aperture and achieve the real-time monitoring of grout pressure, flow velocity, and diffusion distance in a random fracture network. Also, the governing equation of grout flow in a single rough fracture was obtained. The reliability of the test system was proved by the comparison of the single fracture grouting theory with the test results. Moreover, the grouting diffusion mechanism of the random fracture network was studied. The results show that (1) the pressure at the same point in the fracture increased with an increase in the grouting pressure and a decrease in the fracture aperture and was not affected by a change in the grout viscosity. (2) After the grout was dispersed into several branches in the fracture network, the pressures dropped significantly, the flow velocity decreased, and the pressure of each branch and flow distribution coefficient were greatly affected by the angle of bifurcation (intersection) fracture. The development of a test system and study results has a certain guiding value for grouting engineering.
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Acknowledgments
This work was financially supported by the National Natural Science Foundation of China under Grant Nos. 51774267, 51974289, and 41807250. The anonymous reviewers are also deeply acknowledged for reviewing this article and giving their valuable comments.
Notation
The following symbols are used in this paper:
- b
- fracture aperture;
- C1
- constant;
- C2
- constant;
- F0
- output initial strain value;
- Fi
- output strain value corresponding to Pi;
- g
- acceleration due to gravity;
- h
- fracture height;
- K
- calibration coefficient;
- Kg
- permeability coefficient of the rough fracture;
- Pi
- real-time stress value of the sensor;
- p
- grout pressure at any point in the fracture;
- q
- low rate of the grout unit time;
- t
- time;
- v
- flow velocity of the grout at any point;
- vm
- average velocity of the grout forehead;
- x
- diffusion distance of the grout at any time;
- γ
- fracture angle;
- θ
- fracture dip;
- μ
- dynamic viscosity;
- ρ
- grout density; and
- τ
- shear stress of the grout at any point.
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Published In
International Journal of Geomechanics
Volume 21 • Issue 1 • January 2021
Copyright
© 2020 American Society of Civil Engineers.
History
Received: Jan 15, 2020
Accepted: Sep 3, 2020
Published online: Nov 7, 2020
Published in print: Jan 1, 2021
Discussion open until: Apr 7, 2021
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