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

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 241-255
Author(s):  
YongDong Wang ◽  
Yang Liu ◽  
ChuFan Qi ◽  
TianYue Zhou ◽  
Ming Ye ◽  
...  
Keyword(s):  
Flow Rate ◽  
Pipe Wall ◽  
Functional Model ◽  
Drainage System ◽  
Crystallization Rate ◽  
Normal Operation ◽  
Karst Area ◽  
Karst Water ◽  
Flow State ◽  
Drainage Pipe

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.

scholarly journals Parameter optimization of anti-crystallization flocking drainage pipe based on macro force and displacement characteristics of villus

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4127-4135
Author(s):  
Shiyang Liu ◽  
Xuefu Zhang ◽  
Feng Gao ◽  
Yun Li ◽  
Dulaimic Al
Keyword(s):  
Flow Rate ◽  
Drainage System ◽  
Low Flow ◽  
Normal Operation ◽  
Maintenance Cost ◽  
Principal Stresses ◽  
Lining Structure ◽  
Order Of Magnitude ◽  
Drainage Pipe ◽  
Safety And Stability

The crystal blockage of tunnel drainage pipe seriously affects the smoothness of the whole drainage system. Therefore, it is very important to effectively prevent crystal plugging in tunnel drainage system to ensure the safety and stability of lining structure during tunnel operation. Based on the macro force and displacement characteristics of villus, the optimization of villus diameter and villus length of flocked drainage pipe at low flow rate was studied by numerical simulation. The results show that: there is a difference of 1-2 orders of magnitude between the 3-D displacements of the bottom villus and one order of magnitude between the 3-D displacements of the side villus of the flocked drainage pipe; with the increase of villus length, the 3-D displacement of villus increased parabola and with the increase of villus diameter, the 3-D displacement of villus decreased gradually; the results show that the first and third principal stresses of the bottom villus increase linearly with the increase of villus length, while the first and third principal stresses of the side villus increase parabola with the increase of villus length; when the flow rate is 2 cm/s, the diameter of villus is 0.6 mm and the length of villus is 20 mm. Flocking drainage pipe anti crystal plugging technology fills the blank of tunnel drainage pipe anti crystal plugging research. This technology can reduce the maintenance cost of tunnel drainage system during operation, and ensure the safe and normal operation of the tunnel.

scholarly journals Laboratory Experimental Study on Influencing Factors of Drainage Pipe Crystallization in Highway Tunnel in Karst Area

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1493
Author(s):  
Huaming Li ◽  
Shiyang Liu ◽  
Shuai Xiong ◽  
Hao Leng ◽  
Huiqiang Chen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Influencing Factors ◽  
Polyvinyl Chloride ◽  
Normal Operation ◽  
Karst Area ◽  
Pipe Diameter ◽  
Wall Material ◽  
Pipe Material ◽  
Drain Pipe ◽  
Drainage Pipe

The crystalline blockage of tunnel drainage pipes in a karst area seriously affects the normal operation of drainage system and buries hidden dangers for the normal operation of the tunnel. In order to obtain the influencing factors and laws of tunnel drainage pipe crystallization in a karst area, based on the field investigation of crystallization pipe plugging, the effects of groundwater velocity, drainage pipe diameter, drainage pipe material, and structure on the crystallization law of tunnel drainage pipe in karst area are studied by indoor model test. The results show that: (1) With the increase of drainage pipe diameter (20–32 mm), the crystallinity of drainage pipes first increases and then decreases. (2) With the increase of water velocity in the drainage pipe (22.0–63.5 cm·s−1), the crystallinity of the drainage pipes gradually decreases from 1.20 g to 0.70 g. (3) The crystallinity of existing material drainage pipe is: M3 (poly tetra fluoroethylene) > M2 (pentatricopeptide repeats) > M4 (high density polyethylene) > M1 (polyvinyl chloride); M8 (polyvinyl chloride + coil magnetic field) is used to change the crystallinity of drain pipe wall material. (4) When the groundwater flow rate is 34.5 cm·s−1, M1 (polyvinyl chloride) and M8 (polyvinyl chloride + coil magnetic field) can be selected for the tunnel drainage pipe. The research on the influencing factors of tunnel drainage pipe crystallization plugging fills a gap in the research of tunnel drainage pipe crystallization plugging. The research results can provide a basis for the prevention and treatment technology of tunnel drainage pipe crystallization plugging.

scholarly journals Optimization Study of Fluffy Materials Flocking Drainage Pipes to Resist Blockage Based on MD Binding Energy

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 853
Author(s):  
Shiyang Liu ◽  
Xuefu Zhang ◽  
Yuanfu Zhou ◽  
Feng Gao
Keyword(s):  
Aqueous Solution ◽  
Calcium Carbonate ◽  
Binding Energy ◽  
Drainage System ◽  
Normal Operation ◽  
Maintenance Cost ◽  
External Energy ◽  
Adsorption Effect ◽  
Effective Prevention ◽  
Drainage Pipe

Drainage pipe blockage resulting from crystals is one of the causes for cracking and leakage of tunnel lining. Therefore, effective prevention from drainage pipe blockage caused by crystals is crucial to ensure the safety and stability of lining structures during the operation of tunnel drainage system. Based on a large number of indoor model tests and numerical simulation analyses, binding energy between four materials and the calcium carbonate aqueous solution (“solid + liquid” system) and that between the four materials and the two typical growth crystals of calcium carbonate (“solid + solid” system) were studied. The research results indicated that: (1) The four materials all had an adsorption effect on the calcium carbonate aqueous solution system, and the PA6 had the greatest adsorption effect while the PP had the smallest adsorption effect; (2) There was spontaneous adsorption between the PVC or PA6 and the two typical growth crystals of calcium carbonate and no adsorption between the PP or SiC and the two typical growth crystals of calcium carbonate unless external energy was in place; (3) The PP and SiC can be used as the materials for drainage pipe flocking, but it shall be ensured that the fluffy material has a good geometrical property. The prevention technology for crystallization that causes drainage pipe blockage fills the gap in the research of drainage pipe blockage caused by crystals, which can reduce the maintenance cost for the operation of the tunnel drainage system and ensure safe and normal operation of the tunnel.

scholarly journals Comparative analysis of bacterioplankton assemblages from two subtropical karst reservoirs of southwestern China with contrasting trophic status

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qiang Li ◽  
Yadan Huang ◽  
Shenglin Xin ◽  
Zhongyi Li
Keyword(s):  
Trophic Status ◽  
Alpha Diversity ◽  
Decisive Role ◽  
Sensu Stricto ◽  
Karst Area ◽  
Southwestern China ◽  
Rrna Gene ◽  
Karst Water ◽  
Bacterioplankton Community ◽  
Generation Sequencing

AbstractAlthough bacterioplankton play an important role in aquatic ecosystems, less is known about bacterioplankton assemblages from subtropical karst reservoirs of southwestern China with contrasting trophic status. Here, 16S rRNA gene next-generation sequencing coupled with water chemistry analysis was applied to compare the bacterioplankton communities from a light eutrophic reservoir, DL Reservoir, and a mesotrophic reservoir, WL Reservoir, in subtropical karst area of southwestern China. Our findings indicated that Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, Cyanobacteria and Verrucomicrobia dominated bacterioplankton community with contrasting relative frequency in the two subtropical karst reservoirs. Proteobacteria and Bacteroidetes were the core communities, which played important roles in karst biogeochemical cycles. Though WT, TN and DOC play the decisive role in assembling karst aquatic bacterioplankton, trophic status exerted significantly negative direct effects on bacterioplankton community composition and alpha diversity. Due to contrasting trophic status in the two reservoirs, the dominant taxa such as Enterobacter, Clostridium sensu stricto, Candidatus Methylacidiphilum and Flavobacteriia, that harbor potential functions as valuable and natural indicators of karst water health status, differed in DL Reservoir and WL Reservoir.

scholarly journals Impact of Orifice-to-Pipe Diameter Ratio on Leakage Flow: An Experimental Study

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2189
Author(s):  
Tingchao Yu ◽  
Xiangqiu Zhang ◽  
Iran E. Lima Neto ◽  
Tuqiao Zhang ◽  
Yu Shao ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Pipe Wall ◽  
Pressure Head ◽  
Diameter Ratio ◽  
Pipe Diameter ◽  
Leakage Flow ◽  
Leakage Flow Rate ◽  
Different Shapes ◽  
Real Scale

The traditional orifice discharge formula used to estimate the flow rate through a leak opening at a pipe wall often produces inaccurate results. This paper reports an original experimental study in which the influence of orifice-to-pipe diameter ratio on leakage flow rate was investigated for several internal/external flow conditions and orifice holes with different shapes. The results revealed that orifice-to-pipe diameter ratio (or pipe wall curvature) indeed influenced the leakage flow, with the discharge coefficient ( C d ) presenting a wide variation (0.60–0.85). As the orifice-to-pipe diameter ratio decreased, the values of C d systematically decreased from about 12% to 3%. Overall, the values of C d also decreased with β (ratio of pressure head differential at the orifice to wall thickness), as observed in previous studies. On the other hand, orifice shape, main pipe flow velocity, and external medium (water or air) all had a secondary effect on C d . The results obtained in the present study not only demonstrated that orifice-to-pipe diameter ratio affects the outflow, but also that real scale pipes may exhibit a relevant deviation of C d from the classical range (0.61–0.67) reported in the literature.

The Effect of Air Injector on the Performance of Airlift

2012 ◽  
Vol 516-517 ◽  
pp. 1022-1027 ◽  
Author(s):  
Dong Hu ◽  
Chuan Lin Tang ◽  
Feng Hua Zhang
Keyword(s):  
Flow Rate ◽  
Marked Effect ◽  
Pipe Wall ◽  
Tangential Direction ◽  
Air Injection ◽  
Air Flow Rate ◽  
Injection Angle ◽  
Injection Methods ◽  
The One ◽  
Air Lift

In order to investigate the air injection method on the performance of an airlift. For this purpose an air lift system with a riser 2000 mm long and 80 mm in diameter, was designed and tested. Seven different air injection methods were used at a constant submergence. The experimental results showed a marked effect on the airlift performance when operated with different air injection methods. The arrangement of five nozzles gives the best performance, and the one nozzle is the worst. Although the injection angle has a little effect on the airlift performance, but view the general conclusions as a whole, the best lifting efficiency can be obtained when the angle of the nozzle placed along the tangential direction of pipe wall is equal to 10º at a given air flow rate QG =37m3/h.

Seepage through Earth Dams with Chimney Drain on Pervious Foundation

2012 ◽  
Vol 452-453 ◽  
pp. 538-542 ◽  
Author(s):  
Abdelkader Djehiche ◽  
Rekia Amieur ◽  
Mustafa Gafsi
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Drainage System ◽  
Earth Dam ◽  
Earth Dams ◽  
Drainage Systems ◽  
The Earth ◽  
Excess Water ◽  
Effective Drainage

This paper presents an experimental study of a homogenous earth dam. The work is focused to the search of solutions of problems encountered in the earth dams after their construction. One of the major problems is the choice and design of systems of drainage. The effective drainage system to prevent harmful accumulations of excess water is one of the most important roles of dams. Efficient drainage systems can improve the safety of earth dams. The paper presented herein reports the results obtained from the experimental study. Empiric relations have been obtained which can be help in the control of the flow rate in the chimney drain of the earth dams on pervious foundation, which can increase safety earth dams

Effect of Different Molecular Weight of PEG on the Crystallization Behaviors of Binary Polymer Blends PLA/TPS

2021 ◽  
Vol 1035 ◽  
pp. 918-924
Author(s):  
Teng Zhang ◽  
Su Mei Zheng
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
Flow Rate ◽  
Crystallization Rate ◽  
Thermoplastic Starch ◽  
Extrusion Process ◽  
Poly Lactic Acid ◽  
Melt Flow Rate ◽  
Poly Ethylene ◽  
Different Molecular Weight

Serial poly (lactic acid) (PLA) and thermoplastic starch (TPS) blends (with a fixed content of 20 wt.% TPS) were prepared by melt extrusion process. The effect of different molecular weight of PEG on the thermal and rheological properties of PLA/TPS blends was studied by the melt flow rate (MFR) and DSC analysis. The results showed that the molecular weight of PEG influenced the miscibility and crystallization behavior of PLA/TPS blends. Blend added with PEG400 showed a single Tg, and blends with PEG600 provided remarkable improvement of rheological properties with an increase in flow rate to 49.02 g/10 min. 4% content of poly (ethylene glycol) (PEG) can positively contribute to improve crystallization rate of PLA by reducing the melting temperature and cold crystallization temperature.

Numerical Research on Flow Field for Petroleum Tar Cutting Pump

2013 ◽  
Author(s):  
Jing-ning Hu ◽  
Jing Wang ◽  
Rengui Gu ◽  
Ying-ying Tian ◽  
Qun Ye
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Tilt Angle ◽  
Fluid Dynamic ◽  
Reference Value ◽  
Flow State ◽  
Solid Concentration ◽  
Two Phase ◽  
Revolution Speed ◽  
Small Flow

In order to study the flow state and distribution of the solid particle in the flow field of petroleum tar cutting pump, the Computational Fluid Dynamic method was used to conduct the numerical simulation of liquid-solid two-phase flow based on Euler-Euler multiphase flow model and standard turbulence equation. The influence of flow rate, revolution speed and tilt angle of stator slot on streamline and distribution of solid concentration were analyzed. The result shows:strong swirl exists in inlet segment in small flow rate, but flow rate has little influence on the solid concentration, so it has no obvious influence on the cutting and grinding efficiency.Grinding efficiency could be improved by increasing revolution speed, but the requirement for the equipment would be higher, so the revolution speed should be determined reasonably. Reducing the tilt angle of stator slot is favor for improving the grinding and cutting efficiency, so it could provide some reference value for the optimal design.

Sign in / Sign up

Export Citation Format

Share Document