Crystallization law of karst water in tunnel drainage system based on DBL theory

Abstract

When a tunnel is constructed in a karst area, crystallization of the drainage pipe caused by karst water often threatens the normal operation of the tunnel. This work contributes to this field of research by proposing a functional model based on the diffusion boundary layer (DBL) theory proposed by Dreybrodt in the 1990s. The model is formed by determining the flow rate distribution of the drainage pipe in a laminar flow state and turbulent state, and then by applying Fick’s diffusion law and Skelland’s approximate formula. Then, to further verify the applicability of the functional model, a model test was carried out in the laboratory and the test results are compared to the theoretical results. The results show that the crystallization rate of karst water is mainly affected by the roughness of the pipe wall, followed by the slope of pipes. The slope can affect flow state by controlling the flow rate, which in turn affects the crystallization rate of karst water. When the slope of the drainage pipe is 3, 4, and 5%, the error between the experimental results and the theoretical calculation results is 24.7, 8.07, and 27.9%, respectively, and when the liquid level in the pipe is 7.2, 10.2, and 13.3 mm, the error is 27.9, 9.82, and 2.07%, respectively. Considering that the flow will take away the crystalline deposits on the pipe wall in the experiment, although some results have certain errors, they do not affect the overall regularity.

Exploratory Research on Drainage Structure of Highway Tunnel Based on Reducing the Risk of Crystallization Blockage

“…Pipe wall roughness is a major factor influencing the crystallization rate of the tunnel drainage pipe. It is followed by the slope of the pipe wall, which can affect the water flow state by controlling the flow rate, and thus affect the crystallization rate of karst water [19,20]. In the tunnel drainage system, the most straightforward way to increase the groundwater flow rate in the drainage pipe is to increase its slope.…”

“…Tunnel drainage system defect is inevitable. The major research areas for domestic and foreign scholars on the tunnel drainage system range from ion sources, crystal components, and influencing factors to prevention and treatment of crystal blockage, and field survey, numerical analysis, and macro-microscopic tests are adopted as the main research methods [19,20]. The research outcomes can provide a certain reference value to the prevention and treatment of the crystal blockage of tunnel drainage systems; however, the issue cannot be thoroughly addressed.…”

Fault Diagnosis and Maintenance Countermeasures of Transverse Drainage Pipe in Subway Tunnel Based on Fault Tree Analysis

“…The partial pressure of CO 2 has a great relationship with carbonate crystallization sedimentation, and CO 3 2 − is mainly derived from CO 2 dissolved in groundwater [ 31 ]. Liquid velocity, liquid level height, drainage pipe diameter, and the internal wall friction coefficient will also have an important impact on the precipitation crystallization rate of drainage pipes [ 37 , 38 , 39 ]. The precipitation of calcium carbonate depends not only on the hydraulic conductivity and CaCO 3 content of surrounding rock, but also on the properties of lining materials and the geometry of the tunnel [ 40 ].…”

Study on the crystallisation formation mechanism and breakage of tunnel drainage system in dolomite area

“…Park et al 12 analysed the relationship between pipe deterioration and blockages and found that blockages tend to cause deterioration and deterioration of the tunnel. Wang et al 13 propose a functional model based on the diffusion boundary layer (DBL) theory. The results show that the crystallisation rate of karst water is mainly influenced by the roughness of the pipe wall and, to a lesser extent, the slope of the pipe.…”