Abstract
Grouting is widely used for mitigating the seepage of underground water and enhancing the stability of fractured rock mass. After injection, the viscosity of the grout gradually increases until solidification. Conventional multifield analysis models ignoring such effects greatly overestimate the penetration region of the grout and the stability of the grouted rock structures. Based on the 3D unified pipe-network method (UPM), we propose a novel numerical model considering the time-dependent viscosity of the grout, therein being a quasi-implicit approach of high efficiency. The proposed model is verified by comparing with analytical results and a time-wise method. Several large-scale 3D examples of fractured rock mass are considered in the numerical studies, demonstrating the effectiveness and robustness of the proposed method. The influence of the time-dependent viscosity, fracture properties, and grouting operation methods are discussed for the grout penetration process.
Highlights
The existence of discontinuous fractures provides paths for underground water, which reduce the mechanical strength and increase the permeability of the rock mass
Discontinuous fracture network into a 3D system with intersected artificial 1D pipe segments. From this point of view, unified pipe-network method (UPM) is similar to lattice elements approaches (LEM) [70,71,72], both of which simulate complicate 3D processes in an equivalent lower-dimensional system
We present a novel and simple strategy for accounting for the time-dependent viscosity in 3D unified pipe-network method (3D UPM), which is a quasi-implicit method and exploits the advantages of UPM
Summary
The existence of discontinuous fractures provides paths for underground water, which reduce the mechanical strength and increase the permeability of the rock mass. UPM transforms the 3D discontinuous fracture network into a 3D system with intersected artificial 1D pipe segments From this point of view, UPM is similar to lattice elements approaches (LEM) [70,71,72], both of which simulate complicate 3D processes in an equivalent lower-dimensional system. The grouting materials for quickly sealing water-bearing fractures in rock masses possess time-dependent viscosities that increase rapidly after injection due to chemical reactions (solidification), such as with silica sol and cement-silicate sodium grout [73,74,75], which have been proven by experimental investigations [76,77]. A spatialand time-dependent parameter is introduced for indicating the elapsed time of the grouting flow to reach a specific position from the injection point With this strategy, the viscosity of the grout will be updated at every time step, providing results in good agreement with experimental investigations.
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