Measurement of indoor environmental parameters and analysis of the condensation phenomenon in urban utility tunnels

Condensation is a major issue in the safe operation of utility tunnels. To address the condensation problem, the indoor air temperature, relative humidity (RH) and surface temperature in an urban utility tunnel in Jining were continuously measured, and the condensation conditions were surveyed and analysed. The results indicated that under natural ventilation conditions, the air temperature in the comprehensive cabin varied from 23.4°C to 24.5°C, the RH fluctuated between 86.4% and 95.3%, and the corresponding air dew point temperature (DPT) remained in the range of 22.2°C–22.9°C. The surface temperature of the water supply pipeline ranged from 17.8°C to 18.5°C, which was far lower than the DPT in the tunnel, resulting in serious condensation. A water supply pipeline with an anti-condensation design was developed based on environmental test data. A 25-mm-thick rubber plastic sponge insulation layer was used to thermally insulate the water supply pipeline, preventing further dew condensation. Furthermore, mechanical ventilation had little effect on reducing the RH in the tunnel and may actually cause dew condensation; therefore, a ventilation control mode was proposed in this study. These results are expected to provide basic data for further research and reference for the safe management of utility tunnels.

Leakage analysis of campus water supply system based on MLP neural network

Water supply system is an important part of campus public facilities, and the water supply pipeline will leak, not only increase the cost of water supply, but also cause water waste. This paper collects water consumption data of water meters at all levels in a school’s water supply system, establishes MLP multilayer perceptron neural network model, determines the water leakage rate according to the fluctuation of predicted value and actual value, so as to analyze the leakage situation of each school’s water supply system. When the fluctuation between the actual and predicted water consumption exceeds a certain threshold, water leakage occurs on that day. Through solving the model, the following conclusions are finally drawn: (1) the annual water leakage rate of the school is 10.74%, and the water leakage is 29131.418L. (2) The water leakage rate in the first quarter is the highest, and the water leakage in the second quarter is the highest.(3) The school aquaculture area is the most serious leakage phenomenon, and the maximum water leakage rate of each water meter node is more than 10%.

Determination of Blasting Vibration Safety Criterion for HDPE Pipeline Using Vibration and Strain Data in a Coastal Metro Line

A key aspect of urban blasting engineering is evaluating the safety of the blasting dynamic load on the adjacent high-density polyethylene water supply pipeline and controlling the negative impact of the blasting vibration load on the pipeline. According to the special characteristics of the soil layer in Shenzhen coastal city, a field blasting test of a full-scale pre-buried HDPE pipeline was carried out, and the distribution characteristics of the blasting vibration velocity and dynamic strain were analyzed. The finite element model was established by LSDYNA, and the reliability of the calculation model and parameters was verified by comparing with the field test data. At the same time, the dynamic response characteristics of pipelines with different buried depths, operating water conveyance pressures, and diameters under blasting vibration loads were studied. Combined with the circumferential allowable stress control criterion of the pipeline, the safety control standard of the blasting vibration velocity of the HDPE water supply pipeline under different working conditions was proposed. The results show that the circumferential compressive strain of the HDPE pipe is the most affected by blasting vibration, and the pipe with the shortest blasting center distance has the largest response. The vibration velocity and equivalent stress of the pipeline increase with the increase of buried depth, internal pressure, and diameter. The vibration velocity and equivalent stress of the explosion side at the same section of the pipeline are greater than those of the back explosion side. Based on the dimensionless analysis, the vibration velocity prediction model of the buried depth, operating pressure, and diameter of the pipeline is proposed. The safety control velocity of the pipeline is 25 cm/s, and the vibration velocity of the upper surface is 22.5 cm/s according to the Mises yield strength criterion.

Study on the Electrochemical Anticorrosion Effect of Piezoelectric Materials in the Internal Environment of Water Supply Pipeline

The problem of corrosion in water supply pipelines not only poses a considerable threat to the safety of drinking water but also causes a large amount of water wastage due to the leakage of the pipeline network, which can be a chronic problem for a municipal water supply system, as observed in Beijing and other cities in China. In this study, a new piezoelectric PVDF fiber membrane was prepared by electrospinning process, and a piezoelectric anticorrosive film was fabricated based on the internal environment of the pipeline. In the simulated water supply pipeline environment, based on the principle of the piezoelectric effect and the principle of cathodic protection, the electrochemical corrosion protection effect of piezoelectric materials in the water supply pipeline environment, under different water quality conditions, was investigated by a single factor experiment. The results show that piezoelectric anti-corrosion tablets have an obvious inhibitory effect on pipeline corrosion under different pH values, ammonium nitrate concentrations, chloride ion concentrations, and sulfate ion concentrations. Furthermore, under the conditions of pH neutral, alkaline, and high ion concentration, the piezoelectric anti-corrosion sheet can protect the pipeline by 100%. Additionally, since the piezoelectric material can convert mechanical energy into electrical energy and does not cause pollution during the experiment, it has good environmental and economic benefits. The use of piezoelectric materials for preventing corrosion of pipelines is a frontier exploration. We believe that the improvement and development of material properties, and the combination of these new materials and traditional techniques, will provide new ideas and methods for pipeline anti-corrosion technology.

Analysis of Propagation and Distribution Characteristics of Leakage Acoustic Waves in Water Supply Pipelines

Leakage detection methods based on the analysis of leakage acoustic signals provide an effective technical approach for detecting small leaks in water supply pipelines. From a technical perspective, the study of the propagation characteristics of acoustic waves generated by the leakage in the water supply pipeline is necessary for detecting the leak location on the basis of acoustic signals. In this study, a 3D transient leakage acoustic wave propagation equation was derived by combining the principles of fluid dynamics and Lighthill acoustic analogy theory. The propagation of the leakage-induced noise in water supply pipeline was modelled theoretically. We simulated the propagation of a leakage acoustic wave under different conditions for different target scenarios encountered in actual pipeline inspections. Specifically, we analysed the effect of different factors, such as the pipe size and acoustic source characteristics, on acoustic propagation. Finally, the simulated experiments were practically performed using a self-designed simulated water supply pipeline and self-developed spherical water supply pipeline detector to validate the simulation analysis. The results of this study provide a theoretical guidance and basis for the analysis of characteristics of leakage acoustic wave signals and the recognition of leakage conditions in water supply pipelines.

Water potentiality and quality decay of carbonate aquifers of Monti Picentini Regional Park (Southern Italy)

<p>The underground aquifers present in the carbonate massifs of the Monti Picentini Regional Park, captured for various uses (drinking, irrigation and industrial) constitute a fundamental resource to which the Campania, Puglia and Basilicata regions owe a large part of their development. The importance of these deep aquifers is even more evident if we consider that practically all the large aqueducts in southern Italy are fed by them. In particular, the Acquedotto Pugliese S.p.a represents the water resource coming from different resources such us springs located in Campania, artificial reservoirs thanks to potabilizers that make it of excellent quality and extraction from the deep aquifer through wells. This system of large adduction, among the longest in the world (about 5,000 km), ensures the supply of drinking water. The aqueduct of Acqua Bene Comune Napoli S.p.a.  serves over 2,000,000 citizens directly (city of Naples) or indirectly (sub-distributor municipalities) for approximately 295,000 users and with around 200 km of water supply pipeline. And finally, the company Alto Calore Servizi S.p.A. manages the collection, adduction and distribution of drinking water for 125 municipalities in the provinces of Avellino and Benevento, as well as sewerage and purification services for a population of approximately 450,000 inhabitants (approximately 213,500 users). The articulated hydrogeological structure of the territory and the multiplicity of agencies operating and interfering in the management of water resources, necessarily require a well embedded, short and long term planning of the use of groundwater. Considering that the planning must be based on the real potentialities of the aquifers and on the principle of sustainability of the resource, it must facilitate, at interregional level, the processes of interchangeability between the various network systems and guarantee quality and quantity of the resource for multiple socio-economic needs of the users. Moreover, the pollution of these water sources is increasingly manifesting itself as controls become more systematic and comprehensive. This is due to the high number of residential and industrial settlements in the study areas, the massive presence of livestock farms, intensive agriculture, the failure to complete the sewerage networks and therefore the high number of uncollected discharges, the failure to reclaim polluted land. It has been ascertained, in particular, in large areas of the high plain or even of alluvial origin, a significant increase in the concentration of nitrates, for example in the plain of Dragone in the countryside of Volturara Irpina (AV) the values often exceed the limit of 50 mg/l imposed by Italian legal limits for drinking water and are almost constantly over the threshold of attention. Even more alarming is the finding of heavy metals (iron, lead, copper, cadmium, aluminium, trivalent and hexavalent chromium) in some alluvial aquifers (Valley of Solofrana Torrent). In the present work, through the integrated analysis of geological, geochemical and hydrogeological data, found over the last thirty years, we analyzed the causes and relationships that link the factors of propagation of pollutants in the different groundwater bodies.</p>