Abstract
This paper presents an experimental investigation on the main factors that influence the effects of pouring aggregate to plug a tunnel that has been inundated by groundwater to reduce the flow velocity. Moreover, a criterion for plugging the tunnel under infiltrating water to resist flow is proposed. A range analysis and analysis of variance both show that the influencing factors on the efficiency of plugging in descending order is the aggregate particle size, followed by initial velocity of the water flow, and then the water–solid mass ratio. The sedimentation process of the aggregate is likened to the deposition of solid particles into slurry in which the particles settle under gravitational force, thus accumulating at the bottom of the tunnel model due to the forces of the water flow and gravity. The critical velocity of the water that will transport the aggregate without settling can be used as a criterion to determine whether there has been a successful plug of the resistance to flow in the tunnel. The experimental results show that the critical velocity of fine aggregate is less than that of coarse aggregate, and the section with smaller sized aggregate or fine aggregate that resists water flow is flatter. In addition, the required minimum space between two pouring boreholes for a successful resistance to flow is discussed.
Highlights
Mine groundwater disasters have already caused a miserable life price and serious economic loss in the world
PEER REVIEW the main purpose of this study was to experimentally behind practical investigate the deposition of aggregate into a modeled tunnel under the influence of different factors, different factors, including initial velocity of the water flow,aswhich is defined as the steady flow including the initial velocitythe of the water flow, which is defined the steady flow rate before pouring rate before pouring aggregate in the tunnel due to groundwater inrush; aggregate particle size; and aggregate in the tunnel due to groundwater inrush; aggregate particle size; and water–solid mass water–solid mass aggregate ratio
During the process of slurry settling, the aggregate particles are subjected to gravity, buoyancy, impulse force exerted by water, viscous drag forces, and other forces, which cause the aggregate deposits to move against the downstream direction of the water flow relative to the pouring hole of the aggregate
Summary
Mine groundwater disasters have already caused a miserable life price and serious economic loss in the world. The flooding of tunnels in mines and underground spaces due to groundwater inrush is one of the most detrimental disasters, so that there is much urgency to quickly control the water infiltration and restore the operations of underground engineering or mining production after the incident. Grouting has been widely used to address this problem, but, before that is done, pouring an aggregate plug is a major prerequisite to effective grouting so as to plug the tunnel and stop the water flow, which even plays a key role sometimes when the tunnel has a large cross-section area (Table 1). The main purpose of pouring aggregate is to build a section that effectively resists downstream flow to stop the flow and convert it from a confined pipe flow to a seepage flow through a porous medium (aggregates) so that subsequent grouting can be implemented to seal off the tunnel completely. A section that successfully resists flow is formed because of the accumulation of aggregate in the tunnel, which is somewhat similar to the deposition of solid particles of slurry for pipeline
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