Abstract
Self-gravity is one key parameter for behavior characterization of grout permeation and diffusion. This study proposes mathematical models for permeation grouting with consideration of grout self-gravity effect. The models concerning power law, Bingham, and Newtonian grouts are based on the generalized Darcy’s law and spherical diffusion theory. In addition, a prediction model of grout concretion dimension used for Bingham grout was developed. An analysis of the injection pressure distribution law and a comparative evaluation of diffusion radius considering self-gravity effect using established models were conducted subsequently. Moreover, grouting experiments were performed to check and verify the prediction model. The experimental results showed that injection pressure decreases linearly with increase of diffusion radius for the power-law grout, while nonlinear decrease of injection pressure was confirmed in Bingham and Newtonian grouts in this case. Three grouts approximately diffuse in an “ellipsoidal” shape, and it is confirmed that the diffusion radius is closely related to grout self-gravity. The Newtonian grout produces the maximum diffusion radius compared with the other two grouts whether the gravity effects were considered or not. The grout quantity under a smaller water-to-cement w/c ratio exhibits a significant difference and undergoes two increasing stages, whereas the quantity simply tends to be stable after it reaches its maximum in terms of the larger w/c ratios. The constructed dimension prediction model agrees well with the experimental results, which can be helpful for design and assessment of the grouting scheme.
Highlights
Grouting technique has been extensively used in soil reinforcement, water plugging, and deviation rectification of buildings as well as other engineering practices [1,2,3,4,5,6]
Based on grout diffusion behaviors and mechanism, three methods are commonly used for grouting activities, compaction grouting [7], fracture grouting [8,9,10,11], and permeation grouting [12]. ough multiple forms of grout diffusion occur simultaneously in injected soil, one of them often plays a leading role under certain conditions
Materials with large porosity in the sandy layer produce the larger internal pore passages that engender less inhibitory effect during grout flow, which is favorable for effective implementation of the permeation grouting technique [13, 14]
Summary
Grouting technique has been extensively used in soil reinforcement, water plugging, and deviation rectification of buildings as well as other engineering practices [1,2,3,4,5,6]. The clogging theory was utilized to evaluate enhancement effect of the groutability, and the results indicated that usage of the developed equipment increased grout volume and permeation depth by more than 30% and 25%, respectively. Ough a great deal of efforts from scholars and researchers have been made in model modification [32,33,34], few investigations have been made to model the behaviors of the permeation grouting by taking into account the self-gravity effect of the grouts. The generalized Darcy’s law has been utilized to derive grout diffusion models considering impacts of the self-gravity on permeation behaviors for power law, Bingham, and Newtonian grouts and followed by a dimension prediction model of grout concretion. To validate the proposed dimension prediction model, novel experimental equipment including the model box system, the grouting system, the pressure system, and the measurement system has been developed. e proposed model is well checked by the grouting experiments that allow grout flowing through a sand medium as the modeled and measured results are in good agreement with each other
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