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Hydronic snow melting systems are renewable and reliable to eliminate the slippery conditions on the road. In this study, a hydronic snow melting system was implemented in Harbin, China. The characteristics of porous snow were applied to develop a transient two-dimensional model, according to the experimental results. It is the first time that the snow microstructure was considered in the model for the hydronic snow melting system. Three parameters (embedded pipe depth, embedded pipe spacing, and supplied fluid temperature) were compared and analyzed to optimize the design of the hydronic snow melting system in the cold regions. The results indicated that the snow can be cleared in 4.5 h regardless of the fluctuation of parameters. The rank of influence degree was embedded pipe depth > supplied fluid temperature > embedded pipe spacing when the target was the maximum melting rate. However, the rank of influence degree changed as supplied fluid temperature > embedded pipe depth > embedded pipe spacing when the target was the average road surface temperature at the heating time of 6 h. The embedded pipe design should be the embedded pipe depth of 80 mm and embedded pipe spacing of 140 mm at the effects of thermal stress and pipe cost. The control strategy was that the supplied fluid temperature should be 298.15 K in the heating period of 0–1 h, then gradually increased to 308.15 K in the heating period of 1–4 h, and eventually decreased to 298.15 K in the heating period of 4–6 h to save energy. This work can offer a good reference for the optimization and design of hydronic snow melting systems in cold regions.

A field experiment was conducted to study the effect of pipes depth and the distance between them in the smart artificial subsurface irrigation system on the efficiency of the system performance and the yield of sunflower ( Helianths annuus L. ), in one of the fields of Al-Raed Research Station/Ministry of Water Resources located 25 km west Baghdad for the growing season 2022. Two factors were used in the experiment, the first factor included the depths of the subsurface irrigation pipes at three levels 10, 15, and 20 cm. The second factor included the between subsurface irrigation pipes at three levels 50, 60, and 70 cm. The characters studied were soil moisture content %., irrigation water amount, cm 3 h -1 . depth of irrigation water added cm, plant height cm, and sunflower grain yield ton ha -1 . Nested system was used according to the randomized complete block design (RCBD) with three replicates. The pipes depth was allocated to the main plot and the distance in the sub-plots. Least significant difference was used under the probability (LSD 0.05) to compare the averages of treatments. The results showed that the highest and lowest values of moisture content were 23.21 and 16.69 % for treatment depth 20 and distance 60 cm and treatment depth 10 and distance 70 cm, respectively. The highest and lowest values for irrigation water depth were 7.99 and 5.31 cm for the treatment depth 15 and distance 50 cm, and treatment depth 10 and distance 60 cm, respectively. The highest and lowest values for the amount of water consumed were 234.59 and 96.7 cm 3 h -1 for treatments depth 10 and distance 50 cm, and treatment depth 20 and distance 60 cm, respectively. The highest and lowest values for plant height were 150.6 and 117.0 cm for the treatment depth 20 and distance 50 cm and treatment depth 10 and distance 70 cm, respectively. The highest and lowest values of grain yield were 4.97- and 2.62-ton ha -1 for treatments depth 20 and distance 50 cm and treatment depth 10 and distance 70 cm, respectively.

Backward erosion piping (BEP) is a failure mechanism that can affect the safety of water-retaining structures. It can occur when a local anomaly on the downstream side of an embankment causes a concentration of seepage flow at that location. Shallow pipes may then form, progressing in the upstream direction and leading to a collapse of the water-retaining structure. A novel and economically appealing measure against BEP is the coarse sand barrier (CSB), which is now being developed in a multiscale experimental programme in the Netherlands. The method involves placing a trench filled with coarse sand below the blanket layer on the downstream side of the embankment. The CSB prevents the upstream progression of the pipe and significantly enhances resistance to BEP. This paper presents medium-scale laboratory tests involving a range of sands, barrier depths and relative densities. The piping process and the observations of pipe progression in the presence of a CSB are presented, followed by a conceptual model. The presence of a CSB changed the erosion pattern. It resulted in pipe formation perpendicular to the flow direction over the entire width of the barrier before the barrier was damaged. The findings also demonstrate the effect of material properties on pipe initiation, progression and pipe depth. Measurements of the pipe depth are presented and analysed, revealing the significance of pipe depth for understanding the piping process. This analysis shows considerable erosion in the downstream background sand and demonstrates that erosion profiles and measured pipe depths are significantly larger than in BEP tests without a CSB.

Backward erosion piping (BEP) poses a threat to the stability of water-retaining structures. This can lead to severe erosion and collapse of embankments. A novel economically appealing measure against BEP is the coarse sand barrier (CSB). The CSB is a trench filled with coarse sand that is placed below the blanket layer on the landward side of the embankment, which prevents the pipe from developing upstream when it encounters the CSB. Inclusion of a CSB creates a vertically layered sand, which is the situation that can also exist in practice but is different from traditional BEP tests with one homogeneous sand. This paper presents new observations and measurements in medium-scale laboratory tests. 3D measurements of the pipe depth and dimensions are presented and analysed. This analysis indicates how the pipe dimensions evolve during the piping process and shows the erosion mechanism for BEP in vertically layered sands. The findings demonstrate the significance of three-dimensional study of the pipe rather than two dimensions. The pipe depth, width and depth-to-width ratios at the pipe tip in critical erosion stages are measured and presented. In the presented tests, two different erosion behaviours (stepwise pipe progression until failure and straight failure) are found and analysed with respect to possible influential parameters. Higher head drops and flow rates are found in tests with straight failure at the stage before progression. A linear relationship between the hydraulic conductivity contrast (kc) and the critical head drops (hc) is found and observations are used to investigate deviations from the line.

The numerical simulation of air bubbles breakwater was presented in this paper. The two-phase fluid of water and air was assumed as a variable density fluid. The numerical models were developed by FLUENT in order to explore the air amount scale in the system of air bubbles breakwater . The impact of submerged pipe depth on the wave dissipating performance of air bubble breakwater was obtained, which illuminated that The submerged pipe depth D is deeper, the wave dissipating performance of air bubbles breakwater is better. Furthermore, the effect of air amount and the incident wave periods on the performance of the air bubbles breakwater was analyzed.

【Objective】 Subsurface drain is a drainage system widely used in northwestern China to keep the groundwater below the critical depth and facilitate soil salt leaching. This paper presents an experimental study on the combined effect of drain depth and spacing on soil salt leaching in a representative oasis in Yanqi Basin. 【Method】 The drains were buried at the depth of 1.2 or 1.5 m, with the spacing being 20, 30 or 40 m. Overall, there were six treatments. For each treatment, we measured the spatial changes in soil salt contents before and after the leaching, which were then used to analyze the variation in salt leaching efficiency between different treatments. 【Result】 ① When initial soil moisture was at the field capacity, leaching could quickly saturated the soil and displace the water in the soil above the drains. There were no significant correlations between soil moisture content and the depth and spacing of the drains. ② Salt leaching from the top 0-60 cm soil layer was significantly related to the depth and spacing of the drains. The spacing and depth of the drains combined to affect soil salt removal rate. When the spacing was the same, increasing the burial depth of the drains enhanced salt removal from the 0-60 cm soil layer; when the burial depth of the drains was the same, salt removal rate from the 0-60 cm soil layer was the highest when the spacing was 30 cm (P<0.05). ③ As the leaching elapsed, both cumulative water drainage and soil salt leaching increased steadily and then tended to flatten; the electrical conductivity of the drainage water was relatively stable, correlating positively to soil salt content. The cumulative water drainage and leached salt were impacted significantly by the burial depth of the drains (P<0.05) but insignificantly by the drain spacing (P>0.05). Compared to the burial depth of 1.2 m, the burial depth of 1.5 m considerably improved the drainage efficiency and accelerated soil salt removal. 【Conclusion】 For maximum soil salt removal rate, the optimal depth and spacing of the subsurface drains for the study area was 1.5 m and 30 m, respectively.

【目的】研究焉耆盆地典型绿洲农田排盐暗管模式下，布设参数中影响土壤排盐效果的显著因素。【方法】设置不同暗管埋深（1.2、1.5 m）与间距（20、30、40 m），开展排盐试验，结合极差和方差分析方法，研究淋洗前后土壤剖面的水盐变化规律和暗管排水排盐量差异。【结果】①暗管排水过程中，田间持水率状态土壤经淋洗后能迅速达到饱和状态且位于暗管上方的土层能够排出土壤多余水分，土壤含水率与暗管布设参数未呈显著性关系；②在0~60 cm土壤深度内，土壤脱盐率与间距、埋深及组合有显著交互作用，暗管间距与埋深组合与单因素间距相比对脱盐率影响更显著。相同暗管间距下：暗管埋深越深，0~60 cm内的土壤脱盐率越高；相同暗管埋深下：当暗管间距为30 m时，0~60 cm内的土壤脱盐率最高，与20 m、40 m间距有显著差异（P?0.05）；③在排水阶段初期，各处理暗管的排水和排盐量呈现快速增长后逐渐稳定趋势，暗管排水的电导率较为稳定，与土壤剖面的含盐量呈正相关关系。暗管埋深对累积排水和排盐量有显著性影响（P?0.05），间距对其无显著性影响（P?0.05），相较1.2 m深度，1.5 m埋深能有效提升排水效率，加速排出土壤盐分。【结论】在考虑最大脱盐率的情况下，建议将暗管埋深设为1.5 m，间距设为30 m，作为焉耆盆地农田暗管布设的参考。

Taking cemented coal gangue pipeline transportation system in Suncun Coal Mine, Xinwen Mining Group, Shandong Province, China, as an example, the hydraulic calculation approaches and process about gravity pipeline transportation of backfill slurry were investigated. The results show that the backfill capability of the backfill system should be higher than 74.4 m3/h according to the mining production and backfill times in the mine; the minimum velocity (critical velocity) and practical working velocity of the backfill slurry are 1.44 and 3.82 m/s, respectively. Various formulae give the maximum ratio of total length to vertical height of pipeline (L/H ratio) of the backfill system of 5.4, and then the reliability and capability of the system can be evaluated.

Effective urban land-use re-planning and the strategic arrangement of drainage pipe networks can significantly enhance urban flood defense capacity. Aimed at reducing the potential risks of urban flooding, this paper presents a straightforward and efficient approach to an urban distributed runoff model (UDRM). The model is developed to quantify the discharge and water depth within urban drainage pipe networks under varying rainfall intensities and land-use scenarios. The Nash efficiency coefficient of UDRM exceeds 0.9, which indicates its high computational efficiency and potential benefit in predicting urban flooding. The prediction of drainage conditions under both current and re-planned land-use types is achieved by adopting different flood recurrence intervals. The findings reveal that the re-planned land-use strategies could effectively diminish flood risk upstream of the drainage pipe network across 20-year and 50-year flood recurrence intervals. However, in the case of extreme rainfall events (a 100-year flood recurrence), the re-planned land-use approach fell short of fulfilling the requirements necessary for flood disaster mitigation. In these instances, the adoption of larger-diameter drainage pipes becomes an essential requisite to satisfy drainage needs. Accordingly, the proposed UDRM effectively combines land-use information with pipeline data to give practical suggestions for pipeline modification and land-use optimization to combat urban floods. Therefore, this methodology warrants further promotion in the field of urban re-planning.

This study used antennas with frequencies of 250, 500 and 800 MHz and included measurements at four sites with different surface properties. This study aims to evaluate and compare the use of three antennas at different surfaces and depths of sewage pipes and compare the results with actual measurements. Four vertical and parallel paths were scanned at a distance of 0.5 meters. The results of the first site showed the ability of the 800 antennas to detect the presence of a pipe located at a depth of 0.6 meter by reflecting the upper part, where it was able to distinguish the asphalt layers, while the 500 MHz antenna was able to distinguish the shape of the main and secondary pipe located above it. In contrast, the results of using the 250 MHz antenna showed the presence of a reflection in the area where the pipe is located, but the inability to distinguish and determine its location. The results of site B showed the clarity of the radar image in the depths when detecting a pipe at a depth of 0.30 meters compared to the shallower ones when using 800 and 500 MHz antennas compared to the first site. The 800MHz antenna failed to detect the presence of a pipe at site C where it was at a depth of 1.1m but was able to clearly reflect the rebar. A difference in the clarity of the pipe shape reflection was observed when using the 500MHz antenna as the 500MHz antenna was able to distinguish the shape of the pipe at site D where the actual measurements were taken. The results show that the average percentage error was 17% for the four sites.