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

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.

Sustainable Restoration of Degraded Farm Land by the Sheet-Pipe System

For the sustainable restoration of wet farm land degraded by the climate change-induced rise of ground water level (GWL) and soil salinity etc., the sheet pipe system is one of the most useful technologies which reduces cultivation obstacles due to the poor drainage by controlling the rapid drainage function and enabling farmers to produce profitable crops. This system is characterized mainly as a perforated polyethylene rolled-band sheet 180 mm in width and 1 mm thick which is drawn into the subsurface layer while transforming a drainage pipe with φ = 50 mm. The major advantage of this system is that since the sheet pipe is installed without trenching, the disturbance of land is minimized and the construction period can be shortened to about 1/4 (which reduces the cost approximately by 50%). In this study, by using the sheet pipe installed miniature-type model soil box, the drainage capacity of the sheet pipe was confirmed as being the same as the pipe-shaped standard drainage pipes. Based on the observations of the saturated–unsaturated flow and the maximum lowering rate of GWL was predicted. Finally, at the farm land wherein the free board of the adjoining canal was limited, the effectiveness of the sheet-pipe system was confirmed.

Big Data Technology in Intelligent Management and Control System of Drainage Pipe Network

With the rapid development of urban construction, smart city has become an important trend in the future, which is inseparable from the intellectualization of drainage pipe network. At the same time, with the increasing frequency of urban flood disasters, the old drainage pipe network system will cause significant economic losses, which requires modern cities to establish intelligent management and control of drainage pipe network. However, the situation of drainage facilities in most cities in China is complex, which requires strengthening modern means such as monitoring, operation management and planning services. Therefore, the research on intelligent management and control system of drainage pipe network based on big data technology is of great significance. Firstly, this paper analyzes the importance of intelligent management and control system. Then, this paper puts forward the main algorithms for big data processing. Finally, this paper constructs the intelligent management and control system of drainage pipe network.

A Study on Axial Compression Performance of Large Diameter-Thickness Ratio Concrete-Filled Gas Drainage Steel Pipe

A large number of gas drainage pipes are obsoleted in the coal mine gas drainage system, and it causes serious waste. If concrete is poured into the discarded gas drainage pipes as components for underground roadway support, it is very significant for sustainable development of mine. Therefore, it is necessary to study the mechanical properties of the concrete-filled gas drainage steel pipe. Most frequently used gas drainage pipes are spiral welded steel pipe (SSP-I) and spiral external rib steel pipe (SSP-II). In this study, three different concrete-filled steel pipes are taken as the research object: SSP-I concrete-filled steel pipes, SSP-II concrete-filled steel pipes, and RSP concrete-filled ordinary round steel pipes. Through the axial compression test, the failure mode and relationship between stress-strain of concrete-filled steel pipes were obtained. Subsequently, the ultimate bearing capacity of three types of specimens was calculated based on the unified strength theory, limit equilibrium theory, and superposition theory. The test results show that both the SSP-I concrete-filled pipe columns and RSP concrete-filled pipe have good post-peak load-bearing capacity and ductility, and the second peak load reaches 70.38% and 81.92% of the ultimate load, respectively. The load-bearing capacity of SSP-II concrete-filled pipe columns is dropped sharply after bearing ultimate load, and the second peak load reaches only 36.47% of the ultimate load. The failure characteristics of concrete-filled gas drainage pipe columns show that the core concrete is compressed to powder and explain that the gas drainage pipe has fully exerted its restraint on the concrete. The FE method was used to simulate the compression test of three types of concrete-filled steel pipes, and the numerical simulation results show good agreement with the experimental results. Theoretical calculations show that the calculation of concrete-filled gas drainage pipe columns based on the superposition theory EC4-2004 is the closest to the measured value. Therefore, the EC4-2004 standard is recommended to calculate the ultimate bearing capacity of concrete-filled gas drainage pipe columns.

Sources and pathways of biocides and their transformation products in urban storm water infrastructure of a 2 ha urban district

Biocides used in film protection products leaching from facades are known to be a potential threat to the environment. This study identifies individual sources and entry pathways in a small-scale urban area. We investigate emissions of commonly used biocides (terbutryn, diuron, and octylisothiazolinone – OIT) and some of their transformation products (TPs; diuron-desmethyl, terbumeton, terbuthylazine-2-hydroxy, and terbutryn-desethyl) from a 2 ha residential area 13 years after construction has ended. Sampling utilizes existing urban water infrastructure representative for decentralized storm water management in central and northern Europe and applies a two-step approach to (a) determine the occurrence of biocides above water quality limits (i.e., predicted no-effect concentration, PNEC) and (b) identify source areas and characterize entry pathways into surface and groundwater. Monitoring focuses on the analysis of selected biocides and TPs by liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) in water samples taken from facades, rainwater pipes, drainage, and storm water infiltration systems. In standing water in a swale, we found high concentrations of diuron (174 ng L−1) and terbutryn (40 ng L−1) above PNEC for surface water. We confirmed expected sources, i.e., facades. Sampling of rain downpipes from flat roofs identified additional sources of all biocides and two TPs of terbutryn and one TP of diuron. Diuron and terbutryn were found in three drainage pipes representing different entry pathways of biocides. In one drainage pipe collecting road runoff, only diuron-desmethyl and terbutryn-desethyl were detected. In two other drainage pipes collecting infiltrated water through soil, terbuthylazine-2-hydroxy was additionally detected. One of the pipes collecting infiltrated water through soil concentration showed the highest concentrations of terbutryn and two of its TPs (terbutryn-desethyl and terbuthylazine-2-hydroxy). This suggests a high leaching potential of terbutryn. The applied two-step approach determined sources and pathways of biocide and their TPs. This study contributes to expanding knowledge on their entry and distribution and, thus, eventually towards reducing emissions.

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

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.

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

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.

Research on the infiltrations in an earth dam. Case study: Cuibul Vulturilor Reservoir, Vaslui County, Romania

The dam of the reservoir Cuibul Vulturilor, located on the Tutova river is an inhomogeneous earth dam with a maximum height of 15.0 m, with a clayey central core and lateral prisms made of clayey-dusty sands. For tracking the evolution of body dam seepage, 12 piezometers and a drainage pipe with discharge in the downstream connection channel of the bottom outlet are used. The paper presents the characteristic elements of the theoretical infiltration curve in the dam It also shows the hydro isohypses for the dam drawn with SURFER program, using the maximum hydrostatic levels in the piezometers measured in the year 2019. The distribution of the hydro isohypses across the dam is strongly influenced by the location of the piezometers and the other point of measuring the hydraulic head. The pattern circulation of the infiltration water inside the dam body could be studied with increased accuracy, if the dam had been equipped with several piezometers. Even in these conditions, it is clearly observed that the regime of infiltrations through the dam body is similar to the theoretical way of behavior.

TO THE HYDRAULIC CALCULATION OF PRESSURE DRAINAGE PIPELINES, OPERATING IN DISTRIBUTION REGIME

A system of two differential equations which describes the movement of fluid in a pipe with a variable flow rate and the conditions for the fluid outflow through the walls of drainage pipelines into the surrounding soil is considered. It is reasoned that the second term in the original equation, which takes into account energy losses associated with a flow rate variation along the length, can be neglected without a substantial error. The considered system is reduced to dimensionless form by introducing original variables. The coefficient of collecting drainage pipeline resistance «ζl» and the generalized parameter «A», which take into account the structural and hydraulic characteristics of the considered flow, are two main parameters used in the analysis. The concept of an infinitely long drainage pipeline (a pipeline with an infinite walls filtration capacity) is introduced in the article. Also it is noted that such pipeline will have a maximum throughput comparing to pipes of the same diameter but limited length. Quite simple and practical calculated dependencies for the determination of the nature of flow rate variation and pressure drop along the length of the pipeline were received on the basis of the conducted analysis. Important characteristics of pressure distribution pipelines were calculated on the basis of offered formulas. Corresponding graphical dependencies were built for visibility. In particular, graphs of the flow rate variation at the end of the distributor, depending on the design and filtration characteristics of the «soil-drain» system, are presented. Graph that shows the dependence of the variation in the flow rate distribution unevenness along the length of the drainage pipe at various ​​hydraulic conductivity values of the surrounding soil is important for understanding the drainage pipelines particularity. The necessity to take into account the nature of the flow rate connection unevenness along the length for obtaining reliable results for real drainage pipelines calculation is demonstrated.

Study of Electric Field Impact on Crystallization in Tunnel Drainage Pipes in Hard Water Area

To solve the problem of blockage of crystallization in tunnel drainage pipes in hard water area, electric field devices are designed and applied in the transversal tunnel drainage pipe according to the fundamental law of crystallization. Laboratory tests were carried out to test the crystallizing tunnel drainage pipe under the effect of electric field in order to study the law of electric field impact on crystallization in tunnel drainage pipes in hard water area. The test results indicate that the arranged circumferential and parallel plate electric field devices can form an electrical field within a narrow and small space inside the pipe and influence the ion movement in water and adsorption performance between crystals and the pipe. Under the condition of full flow, the amount of crystals in the ordinary pipe without electric field treatment increases progressively along water flow direction and remains relatively uniform later. The amount of crystals along the water flow direction of the pipe treated with circumferential and parallel plate electric fields presents signs of fluctuation in the early stage and then stableness later. The amount of crystals in the fluctuating section is higher and lower in the uniform section, and its uniform section length is longer than that in ordinary pipes. Under the condition of full current, crystallizing speed declines with elapse of running time. After the electric field is imposed, crystallizing acceleration progressively decreased to a relatively lower level. Comparing three voltages of 5 V, 12 V, and 24 V, the effect of scale inhibition under 5 V is superior. When water amount in the pipe varies, the effects of scale inhibition under different electric field modes are different. The electric field effect causes the changes of the external form of calcium carbonate crystal and its surface abrasion, porous crystal, and structural looseness.