Investigation and Analysis on Crystallization of Tunnel Drainage Pipes in Chongqing

Zhang, Xuefu; Zhou, Yuanfu; Zhang, Bin; Liu, Shiyang

doi:10.1155/2018/7042693

Cited by 23 publications

(17 citation statements)

References 17 publications

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“…The cross section of the research pipe is semicircle. Flocking drainage pipe has a villi (nylon wire) diameter of 1 mm, longitudinal spacing of 25 mm, and circumferential spacing of 8.72 mm (10 ). The solution required for the test was prepared according to the ratio of m (CaCl 2 ):m (NaHCO 3 ):m(H 2 O) to 1:3:10 of analytical pure calcium chloride reagent and sodium bicarbonate reagent.…”

Section: Experiments Designmentioning

confidence: 99%

“…Liu et al 9 analyzed the change rule of the external water pressure of the lining after the unsymmetrical blockage of the drainage system of the tunnel. Zhang et al 10 and Zhou et al 11 carried out a large number of field investigations on the drainage pipe plugging by crystallization, thus determined that the main component of crystallization was calcite crystal calcium carbonate through micro analysis, and finally designed a series of laboratory tests on anti-crystallization. Xiang 12 analyzed the stress response of lining after the blocking of blind drain pipes in water-rich tunnels by numerical simulation.…”

Section: Introductionmentioning

confidence: 99%

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Experimental study on anti‐crystallization law of tunnel transverse flocking drainpipe at different velocities

Liu

Gao

Zhang

et al. 2020

Asia-Pacific J Chem Eng

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With the increasing of the tunnel operation life, various diseases of the tunnel are gradually highlighted, especially the lining cracking and leakage caused by the crystal blocking pipe of the drainage system, which brings serious hidden trouble to the safe operation of the tunnel. In order to solve the problem of crystal plugging of horizontal drainage pipe in tunnel, the transverse drainage pipe of the tunnel was taken as the research object, combined with the field survey data, and the indoor test was used to analyze the anti‐crystallization law of flocking drainage pipe at different velocities. The results showed that the flocking drainage pipes had an anti‐crystallization effect, and the anti‐crystallization efficiency could be increased by more than 50% compared with the ordinary drainage pipes, and the flow rate at 6.82 cm/s could reach more than 60%. At the flow rate of 5.46 cm/s, the crystallization on flocking drainage pipes at the later stage of the test remained basically unchanged and was less than that on ordinary drainage pipes. The change in the weight of crystals on the flocking drainage pipes was approximately sinusoidal, and the change period was different at different flow rates; among which, the change period of crystallization on the flocking drainpipe was shorter when the villi length was shorter at low flow rates.

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Section: Experiments Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental study on anti‐crystallization law of tunnel transverse flocking drainpipe at different velocities

Liu

Gao

Zhang

et al. 2020

Asia-Pacific J Chem Eng

Self Cite

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“…Rinder et al believed that the precipitation produced by the chemical reaction when groundwater flowed through the initial support shotcrete and the crystallization resulting from environmental factors after the solution entered the drainage pipe were the main sources of crystals in the tunnel drainage pipe [7]. Zhang et al found that crystals in the tunnel drainage system were predominantly calcite composed of CaCO 3 [8]. Xiang Kun et al concluded that the pH value of groundwater had a significant impact on the number of crystals, namely, the higher the pH value, the more likely it was to produce crystals in the drainage pipe [2].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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Crystal blockages of tunnel drainage systems severely undermine the tunnel lining structure and operation safety. In order to reduce the risk of crystal blockages of tunnel drainage systems, the distribution of highway tunnel defects was identified through a field survey, indoor test, and literature analysis, and an optimization method of tunnel drainage structures was proposed. The research suggested the following: (1) Lining water leakage and construction joint water leakage were the most common defects in the tunnel drainage system of Renhua–Xinfeng Expressway and Yingde–Huaiji Expressway in Guangdong Province, accounting for 60% and 32% of total defects, respectively. The number of defects that occurred in the drainage system of the tunnel was larger in the granite formation, with the number of road seepage and inspection chamber crystallization incidents reaching 2.5/km and 2.8/km, respectively. (2) The groundwater was mainly alkaline with a pH value of 8~12, Ca2+ (107 mg/L) was the cation with the largest ion concentration, and HCO3− (165 mg/L) was the anion with the largest ion concentration. The crystals in the tunnel drainage system were predominantly square, spindle, and rhombic calcite and aragonite composed of CaCO3, mixed with a small amount of sediment. (3) To reduce the risk of crystal blockages of the tunnel drainage system and ensure tunnel lining structure safety, a threefold optimization measure was proposed, namely, setting one-directional drainage pipes between the cable trench and the roadside blind drainage ditch, applying “π” type anti-crystallization drainage water-stop belts at the circular construction joints in the secondary lining, and both increasing the slope of the transverse drainage pipe and using an anti-crystallization drainage pipe. The research results will play an important role in guiding the design, construction, and maintenance of highway tunnel drainage systems in China.

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“…In view of the problem of crystallization blockage in the tunnel drainage system, the current focus is mainly on three aspects: the analysis of crystal composition, the analysis of crystallization influencing factors and the technology to prevent crystallization. The main component of the crystalline material of the tunnel drain pipes is insoluble rectangular calcium carbonate crystals [4][5][6] such as calcite crystal, and the calcium element in the crystal is derived from the groundwater [4,7] in the tunnel and the cement [8] in the shotcrete. The main influencing factors of crystallization-induced blockage include CO 2 partial pressure, flow velocity, temperature, pH, ion type and concentration [9,10].…”

Section: Introductionmentioning

confidence: 99%

Anti-Blocking Mechanism of Flocking Drainage Pipes in Tunnels Based on Mathematical Modeling Theory

2021

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Crystalline pipe plugging in tunnel drainage systems is one of the causes of tunnel lining cracking and water leakage. Therefore, effective prevention of crystalline pipe blockage in tunnel drainage systems is very important to ensure the safety and stability of the lining structure during tunnel operation. Combined with the theories of fluid mechanics, structural mechanics and basic physics, the flocking and anti-blocking mechanism of drainage pipe was comprehensively analyzed by using the method of mathematical modeling, including: (1) the calculation expression of average velocity of the flocked section of a flocked drainage pipe v = Q/(C1 − C2(r + r′)) and the calculation formula of flowing water pressure under the action of groundwater Fw = KAγQ2/(2g(C1 − C2(r + r′))2); (2) the flow velocity v0 in the flocked drainage pipe shall meet v2 < 4gπrlτ1/γKA, crystals will be attached to the fluff and the crystals will maintain dynamic balance; (3) the flow velocity v0 in the flocked drainage pipe shall meet v2 ≥ 4gπrlτ1/γKA, crystals will not adhere to the fluff and the flocked drainage pipe will remain unobstructed. The research on the mechanism of preventing blockage of flocking drainage pipes fills the gap in research theory in this regard, contributes to the popularization and application of blocking prevention technology of flocking drainage pipes, reduces the maintenance cost during operation of tunnel drainage systems and ensures the safe and normal operation of tunnels.

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Investigation and Analysis on Crystallization of Tunnel Drainage Pipes in Chongqing

Cited by 23 publications

References 17 publications

Experimental study on anti‐crystallization law of tunnel transverse flocking drainpipe at different velocities

Experimental study on anti‐crystallization law of tunnel transverse flocking drainpipe at different velocities

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

Anti-Blocking Mechanism of Flocking Drainage Pipes in Tunnels Based on Mathematical Modeling Theory

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