Hasil untuk "Hydraulic engineering"

Xianwu Luo, Bin Ji, Y. Tsujimoto

Xiaojie Yang, Xuhui Kang, Manchao He et al.

The 110 mining method is a novel coal mining approach that is environmentally friendly. To investigate the movement laws of the overburden strata under the mining conditions of this method, this study systematically analyzed the development characteristics and formation mechanisms of the “three zones” of the overburden strata (caving zone, fractured zone, and flexural subsidence zone). A predictive model for the development height of the “three zones” was established based on the mining damage invariant equation and the pressure arch theory, and a quantitative criterion for the boundary between the caving zone and fractured zone was proposed.To verify the reliability of the model, the 8302 working face of Jinjiazhuang Coal Mine was selected as the research object. A combination of theoretical analysis and on-site monitoring was employed to conduct prediction and in-situ monitoring experiments on the height of the “three zones” and the surface conditions of the goaf. The results show that the relative error between the predicted height of the caving zone by the model and the measured value is +0.38 ​m, and the relative error for the fractured zone height is −1.55 ​m, indicating a high prediction accuracy.The predictive model established in this study provides a theoretical basis for the safe and efficient mining as well as the overburden control in the 110 mining method. The research findings have significant engineering application value for promoting the development of green coal mining technologies.

Fatemeh Mehrpourbernety, Ramin Fazloula, Alireza Emadi et al.

Extended Abstract Background: Floods are caused by several reasons, including rainfall intensity, vegetation destruction, and encroachment of rivers. The high power of floods damages buildings, bridges, and existing structures, and also reduces the capacity of the river bed. Moreover, the excessive volume of water leads to human and financial losses and the destruction of animal habitats. Structural measures (such as dam construction) and non-structural measures (such as increased vegetation coverage, forecasting, and flood warning systems) are carried out to deal with a flood and its damage. Flood forecasting is the process of estimating the time and place of flood occurrence and the volume of water and, as an efficient and low-cost tool for flood management and damage reduction, has received a lot of attention in recent years. Rainfall-runoff modeling is one of the measures of flood management. Simulation is done using hydrological models to understand the relationship between rainfall and runoff parameters, as well as to determine the peak discharge value and the time to reach the peak discharge. One of the hydrological software packages in this field is the HEC-HMS software. By considering three components of the basin, meteorological, and control specification models, the value of losses, runoff, base flow, and routing are calculated using existing methods, and finally, optimization is performed to reduce the difference between observed and simulated hydrographs. Precipitation is one of the most important input parameters in simulating floods. Therefore, the correct estimation of its amount is considered necessary and important. Considering the number of rain gauge stations and the lack of sufficient stations in Iran, especially in mountainous areas, the use of numerical weather prediction model information and satellite rainfall data plays an important role in flood forecasting. Numerical weather prediction models predict weather conditions using mathematical models. Forecasts are divided into three short-range, medium-range, and long-range categories, and also, into regional and global models. One of these models is the numerical weather prediction model, called GFS, which predicts and provides data such as temperature, wind, and precipitation. Heavy rainfall, destruction of forests, sand and gravel harvesting, and construction in floodplains are among the causes of floods in Mazandaran Province, especially the Tajan River, in recent years. The main goal of this research was to estimate the value of peak discharge by simulating flood events and evaluating the results using the precipitation information of the GFS model in the Tajan watershed located in Sari City, Mazandaran Province. Methods: In this research, data were collected from the hydrometric stations of the Tajan watershed, including the hourly measurements of recorded floods, as well as the information required by the evaporation and rain gauge stations in this area, including precipitation obtained by the Mazandaran Regional Water Company for the 10-year period of 2011-2021. Furthermore, precipitation data were received online (from the following webpage: https://openweathermap.org) through the output of the GFS numerical weather prediction model in the mentioned period. The curve number of each subbasin was determined using land use and soil hydrological group layers in ArcGIS software, and the physiographic characteristics of the Tajan watershed were extracted using the HEC-GeoHMS extension. Then, four events 04 October 2011, 01 December 2011, 14 November 2016, and 01 December 2017 were simulated using the physiographic characteristics of the sub-basins, the precipitation data of the Tajan watershed, and the flood discharge obtained by the Mazandaran Regional Water Company in HEC-HMS software. The Soil Conservation Service curve number method was used to calculate losses, the SCS unit hydrograph method was used to calculate the runoff method, and the lag method was used for routing. Subsequently, sensitivity analysis was performed to determine the sensitivity of the curve number, lag time, and initial abstraction parameters. The optimal values of the parameters in the optimization process were determined using nine objective functions available in the HEC-HMS software, including Mean of Absolute Residuals, Mean of Squared Residuals, Peak-Weighted Root Mean Square Error, Peak-Weighted Variable Power, Percent Error in Peak Discharge, Root Mean Square Error, Sum of Absolute Residuals, Sum of Squared Residuals, and Time-Weighted RMSE. In the next step, validation was performed by event 01 December 2017 using the optimal values of the parameters. Finally, after HEC-HMS software optimization and verification, the aforementioned flood events were simulated using the data of the GFS numerical weather prediction model. Results: The results showed a strong correlation between observed and calibrated hydrographs. Besides, the best objective function was peak-weighted variable power. The results of the sensitivity analysis showed that the peak discharge was more sensitive to the changes in the initial abstraction and curve number parameters. Validation was performed to verify the validity of the results obtained in the calibration process, and the results indicated no significant differences between the averages of the two groups, viz. observed and calibrated flow rates. Moreover, the simulation results using the GFS numerical weather prediction model showed no significant differences (at a 95% confidence level) between the observed and simulated hydrographs. Conclusion: According to the results, using the precipitation data of the GFS numerical weather prediction model and the HEC-HMS rainfall-runoff software makes it possible to simulate the flood with acceptable confidence in predicting the peak discharge of floods.

D. Ma, M. Rezania, Hai-Sui Yu et al.

The evaluation of the hydraulic properties evolution of granular sandstones in relation with groundwater inrush within faults is an important issue for mining engineering applications. This paper presents the results of an experimental investigation of small particle migration from granular sandstone samples under different original porosities, particle size compositions and water flow pressures. A new rock testing system has been setup to carry out the tests. Based on the results, it is observed that the overall permeability evolution during the tests can be divided into four different phases, including i) re-arrangement of large rock fragments, ii) water inrush with substantial particle migration, iii) continued moderate particles seepage, and iv) steady state water flow. The crushing of edges and corners of large rock fragments, and the evolution of the fracture network has mainly been observed in the first two phases of the tests. The results indicate that the migration of small particles has an essential effect on permeability and porosity increase during water inrush through fractured sandstone. The samples with higher original porosity, higher percentage of fine particles in their formation and under higher water flow pressures, achieve higher permeability and porosity values when the test is complete. Furthermore, using the measured data, the performances of a number of empirical models, for permeability evolution in fractured porous media, have been studied. The prediction results indicate that not all of the fractures in a sample domain contribute in small particle migration. There are parts of the fracture network that are not effective in particle flow, a sample with less original porosity, more fine particles and under lower water pressure shows less ineffective fractures. Therefore, using the concept of the effective porosity (fracture) is sufficient enough for the flow calculation.

Yanyu Dai, Fan Lu, Benqing Ruan et al.

Quantitative differentiation of climate and human activities on runoff is important for water resources management and future water resources trend prediction. In recent years, runoff in the middle reaches of the Yellow River (MRYR) has decreased dramatically. Many studies have analyzed the causes of runoff reduction, but there is still a lack of understanding of the spatial differences in runoff contributions and their causes. Therefore, this study quantitatively distinguishes the contributions of climate and human activities to runoff changes in nine sub-basins of the MRYR based on the Budyko framework and analyses the differences in the contributions of different basins and their causes. The results show that the runoff in the nine sub-basins decreases significantly and the precipitation increases from northwest to southeast. The contribution of human activities to runoff is greater than that of climate change, especially in the Huangfuchuan (HF) River and Kuye (KY) River basins, where the contribution of human activities to runoff exceeds 90%. The greater impact of human activities in HF River and KY River is due to the significantly higher water use growth rate and normalized vegetation index trends than in other areas. HIGHLIGHTS Spatial differences in the causes of runoff variation in nine small watersheds in the middle reaches of the Yellow River were analyzed.; The influence of NDVI and human water extraction cannot be ignored.;

Danya N. Hussein , Shatha H. D. AL-Zakar, Abdulwahab Mohammad Yonis

The relationship between the rainfall intensity, duration, and frequency (IDF) is widely used in water resources engineering in designing hydraulic structures, such as culverts and sewage systems, and for reducing and controlling floods. In this study, the curves of (IDF) were found for five rain stations registered in different regions in northern Iraq, i.e., Mosul, Tal-Afar, Sinjar, Rabia, and Tal-Abta, and for different periods extending from 1990 to 2019. The Indian Meteorological Department (IMD) empirical equation was utilized to obtain data during short periods, i.e., 10, 20, 30, 60, 120, 180, 360, 720, and 1440 minutes. Also, three probability distributions were used: the Gumble Distribution, the Log Pearson Type III Distribution, and the Log-Normal Distribution, for various return periods (2, 5, 10, 25, 50, and 100) years. Easy fit 5.6 software includes the tests (Kolmogorov-Smirnov, Anderson -Darling (AD), Chi-Squared (χ2)) was used to determine the most suitable distribution for the observed data among the three used distributions. The results demonstrated an insignificant difference between the three applied distributions and the statistics values that fell within the significance level, with priority to the Log Pearson-III distribution.

Ye Zhang, Jinqiao Chen, Yanlong Li

Objective Borehole Televiewer (BHTV) imaging serves as an effective tool for analyzing deep rock formations in geological engineering, offering crucial insights into surface discontinuity extensions and the distribution of buried discontinuities, especially within complex geological environments associated with hydraulic engineering projects. Recognizing the current issues of subjectivity and low efficiency, prevalent in the manual calculation of rock discontinuity morphological characteristics within rock masses, we propose an intelligent approach for segmenting geometric data from digital borehole images. Leveraging the segmentation outcomes, an image thinning technique is employed to facilitate precise quantitative analysis of borehole data. Methods In this research, we employ deep learning models to intelligently identify fractures within BHTV images, utilizing various network structures such as Unet, SegNet, and DeepLabV3. The recognition results are compared with traditional image processing methods, demonstrating the advantages of deep models in accurately segmenting complex geological images. Furthermore, we enhance the model's performance by incorporating an attention mechanism into the encoder-decoder process.Once precise segmentation of rock discontinuities is achieved, the fracture skeleton is extracted using the image thinning method, representing fractures as one-pixel-width curves. Ultimately, automated calculations is completed for dip strike, dip angle, and fracture thickness. Results This method is applied to segment and calculate borehole televiewer images in hydraulic engineering. Comparing the results of manual extraction and automatic extraction of fracture information, the error of dip strike and dip angle is less than 3°, and the fracture thickness error is less than 0.65 mm. Conclusion The results verify that the intelligent calculation method of fracture information proposed in this paper. The proposed method has wide application prospects in hydraulic engineering.

M. He, Jiapei Zhou, Panfeng Li et al.

Characterizing the spatial distributions of hydraulic conductivity of rock mass is important in geoscience and engineering disciplines. In this paper, the architecture of CNN is proposed to predict the spatial distributions of hydraulic conductivity based on limited geologic factors. The performance of CNN model is evaluated using the new data of hydraulic conductivity. A comparative study with the empirical method is performed to validate the reliability of CNN model. The effect of weathering and unloading on the spatial distributions of hydraulic conductivity is studied using the CNN model. The result shows that the hydraulic conductivity predicted by CNN model is within the error range of 5% compared to the Lugeon borehole tests. The predictive accuracy of the CNN method is higher than the estimations of the empirical relations. The spatial distributions of hydraulic conductivity versus depth can be divided into three stages. At first stage, the hydraulic conductivity is slightly reduced with the increasing of depth. Increasing to the depth range of 300-600 m (second stage), the hydraulic conductivity is slightly reduced as a function of lower weathering degree. At last stage, the hydraulic conductivity is not changed by the weathering, and converge to a constant with the depth increasing.

Zhou Tong, Wang Haibo, Fengxia Li et al.

Abstract The main area of the Jiaoshiba anticline of the Fuling shale gas field was taken as the research object, laboratory rock mechanical experiments and direct shear experiments were conducted to clarify the mechanical anisotropy characteristics and parameters of rock samples with rich beddings. Based on the experimental results, a 3D fracture propagation model of the target reservoir taking mechanical anisotropy, weak bedding plane and vertical stress difference into account was established by the discrete element method to analyze distribution patterns of hydraulic fractures under different bedding densities, mechanical properties, and fracturing engineering parameters (including perforation clusters, injection rates and fracturing fluid viscosity). The research results show that considering the influence of the weak bedding plane and longitudinal stress difference, the interlayer stress difference 3–4 MPa in the study area can control the fracture height within the zone of stress barrier, and the fracture height is less than 40 m. If the influence of the weak bedding plane is not considered, the simulation result of fracture height is obviously higher. Although the opening of high-density bedding fractures increases the complexity of hydraulic fractures, it significantly limited the propagation of fracture height. By reducing the number of clusters, increasing the injection rate, and increasing the volume and proportion of high-viscosity fracturing fluid in the pad stage, the restriction on fracture height due to the bedding plane and vertical stress difference can be reduced, and the longitudinal propagation of fractures can be promoted. The fracture propagation model was used to simulate one stage of Well A in Fuling shale gas field, and the simulation results were consistent with the micro-seismic monitoring results.

Zihao Sun, Liang-qing Wang, Jia-Qing Zhou et al.

Abstract Understanding fluid flow in rock fractures is relevant to many engineering applications, including underground nuclear waste disposition, oil and gas exploitation, dam and slope design, as well as contaminant transport. Rough rock fracture is usually idealized as two parallel plates separated by the hydraulic aperture, the determination of which is key to solving seepage problems in fractured rock using the cubic law. The mechanical aperture and fracture morphology are the main aspects affecting the hydraulic aperture. Here, an innovative hydraulic aperture prediction equation for two-dimensional fractures is established based on the mechanical aperture and fracture morphology. Six parameters were firstly selected to predict the hydraulic aperture, including three mechanical aperture parameters and three fracture morphology parameters. A training database was then established from numerical experiments of 300 fracture models, which were built based on Barton's 10 standard profiles and their combinations. The numerical experiments were conducted with FLUENT software. Based on the database, a hydraulic aperture prediction model was established using the support vector machine theory and the particle swarm optimization algorithm, which was transformed into an explicit equation. Finally, 20 natural fractures were used to validate the performance of this equation, with the comparisons of four existing empirical equations. The results show that this method worked well in predicting the hydraulic aperture. This method provides an alternative and effective way to directly determine the hydraulic aperture using the geometry information of rough rock fractures.

Haike Wang, H. Qian, Yanyan Gao

Abstract Determining the mechanism of water flow in loess involves many problems that are vital to science and engineering. Water flow through loess has usually been assumed to follow Darcy's law, but this has not been properly validated. The main objective of this study is to validate the applicability of Darcy's law for loess. For this purpose, we conducted constant-head permeability experiments and mercury injection porosimetry (MIP) on loess specimens of different dry densities. The results indicate that Darcy's law is not suitable for describing water seepage in loess at low hydraulic gradient, since there is a threshold hydraulic gradient (i0) below which no flow is observed and a critical hydraulic gradient (icr) below which the relationship between the hydraulic gradient (i) and seepage velocity (v) is non-linear. The MIP results show that variation in hydraulic conductivity is closely related to the pore size distribution (PSD) in loess specimens. i0 is positively correlated with the content of pores with diameters in the range of 0.01–1 μm and negatively correlated with the content of pores with diameters larger than 3 μm. The existence of bound water on loess is the main reason that its permeability deviates from Darcy's law. The mechanism of water movement in loess can be fully understood by considering the effect of bound water.

Prasanna S. Mahankar, A. Dhoble

ZUO Daxing, ZANG Chuanfu, WANG Lina

Evaporation is an important link in the water cycle,and in-depth studies on the influence of various meteorological factors on evaporation changes are of great significance for climate change,ecological restoration,and utilization of water resources.In this study,the Penman-Monteith model modified by the Food and Agriculture Organization of the United Nations (FAO) is used to calculate the potential evaporation (ET₀) in the Pearl River Basin from 1980 to 2019.The Mann-Kendall non-parametric test method and inverse distance weighting method are used to analyze the spatial and temporal distribution characteristics of the ET₀,and the principal component analysis method is used to analyze the influencing factors.The results show that:① The average ET₀ of the Pearl River Basin is 1 145.8 mm,and the growth rate is 1.37mm/a,which shows an increasing trend.In terms of four seasons,the growth rate increases in spring (0.56 mm/a),autumn (0.4 mm/a),and winter (0.44 mm/a) but decreases in summer (-0.03 mm/a).② In terms of spatial distribution,the annual average ET₀ of the Pearl River Basin is high in the east,west,and south but low in the middle andnorth.The distribution of ET₀in summer,autumn,and winter is similar.However,the distribution of ET₀ in spring is opposite to that in summer,autumn,and winter.③ Temperature,average water vapor pressure,and altitude are the leading factors of ET₀ changes.Factors such as temperature,average water vapor pressure,sunshine duration,and wind speed make positive contributions to ET₀,while altitude,latitude,and relative humidity make negative contributions to ET₀ changes.

Roghayeh Ghasempour, Kiyoumars Roushangar, V. S. Ozgur Kirca et al.

Beside in situ observations, satellite-based products can provide an ideal data source for spatiotemporal monitoring of drought. In this study, the spatiotemporal pattern of drought was investigated for the northwest part of Iran using ground- and satellite-based datasets. First, the Standardized Precipitation Index series were calculated via precipitation data of 29 sites located in the selected area and the CPC Merged Analysis of Precipitation satellite. The Maximal Overlap Discrete Wavelet Transform (MODWT) was used for obtaining the temporal features of time series, and further decomposition was performed using Ensemble Empirical Mode Decomposition (EEMD) to have more stationary time series. Then, multiscale zoning was done based on subseries energy values via two clustering methods, namely the self-organizing map and K-means. The results showed that the MODWT–EEMD–K-means method successfully identified homogenous drought areas. On the other hand, correlation between the satellite sensor data (i.e. the Normalized Difference Vegetation Index, the Vegetation Condition Index, the Vegetation Healthy Index, and the Temperature Condition Index) was evaluated. The possible links between central stations of clusters and satellite-based indices were assessed via the wavelet coherence method. The results revealed that all applied satellite-based indices had significant statistical correlations with the ground-based drought index within a certain period. HIGHLIGHTS Discussing the spatiotemporal variations of drought using in situ observations and satellite-based datasets.; Applying the hybrid MODWT–EEMD–K-means method for catching similar zones.; Discussing the possible links between the SPIs of the central stations of clusters and satellite-based drought indices via the wavelet coherence (WTC) method.; Evaluating drought conditions using the satellite-derived NDVI and LST products.;

O. Diegel, J. Schutte, Arno Ferreira et al.

Abstract This article examines the process of redesigning a conventionally manufactured hydraulic manifold to one designed for additive manufacturing (DfAM). In this case, the factors to be optimized included minimizing the support material, and post-processing required to make the part, as well as minimizing the products’ weight and print time. Improvement in product functionality would also be a desirable outcome of the project. The paper also compares the new and old manifold in terms of material usage, weight, costs, Manhattan distances, and residual stress. The DfAM process used in this article includes the steps of removing all material that doesn’t serve a specific engineering function, exploring the effects of different print orientations, techniques for eliminating support material and post-processing. These techniques are demonstrated in the redesign of the hydraulic manifold and present the resulting printed product. The design steps used in the case study are also described in a generic manner to make them applicable to other AM parts printed in either metal or polymer.

I. Fujita, M. Muste, A. Kruger

Ruxin Zhang, B. Hou, Hui-Duck Han et al.

Abstract A complex fracture network, which is the precondition of stimulated reservoir volume for shale formation, depends on the interaction between hydraulic fractures and discontinuities, such as bedding planes and natural fractures. However, the fracture propagation behavior in laminated shale formation still maintains ambiguous and the formation mechanism of complex fracture network has not been well understood. Therefore, hydraulic fracturing simulated experiments were conducted on shale outcrops to clarify above issues under the effects of multiple factors, such as horizontal stress difference, pump rate, and fluid viscosity. The results reveal that dilation and crossing are two main hydraulic fracture propagation behaviors because of discontinuities influencing, resulting in three categories of the ultimate fracture morphologies. Simple fracture is a single induced fracture. Complex fracture is consisted of two or more induced fractures which do not link up with each other. However, network fracture includes induced fractures which interweave with each other like a network. All the fracture geometries are generated under the mutual interaction of natural factors and engineering factors. A large horizontal stress difference and a high fracturing energy reduce the complexity of fracture geometry, whereas, a small horizontal stress difference and a low fracturing energy enhance the activated probability of discontinuities, resulting in a complex fracture network. Furthermore, weak cementing strength and large opening degree of discontinuities increase the complexity of the fracture. In addition, the fracturing curve reflects fracture morphology indirectly. Simple fracturing curve and steady extensive pressure indicate the simple fracture. The rising extensive pressure implies the complex fracture, whereas, the fluctuation of fracturing curve suggests the network fracture. In the meantime, each fracture morphology has its own dimensionless net pressure features, which could be applied to judge fracture morphology in shale formation.

Chong Lin, Jianming He, Xiao Li et al.

B. Liu, Ningyuan Wang, Minghui Chen et al.

REN Mengzhi, LIU Dengfeng, YANG Yuanyuan et al.

Events of reservoir with loss of regulation capacity include failure of reservoir tostore water or discharge water due to abnormal operation of discharge structures. Emergencyscheduling of reservoir with loss of regulation capacity can effectively reduce the adverseimpact. This paper establishes an evaluation index system for extreme events such as completefailure of reservoir to store or discharge water, with the criteria layer including reservoirsafety, water supply, power generation and ecology and the index layer including the durationratio of reservoir over-check water level, ratio of maximum change range of reservoir water level,ratio of water supply guarantee, vulnerability of water supply, maximum water shortage rate,minimum output ratio, loss of power generation benefits, ratio of time to meet ecological flow andthe satisfaction degree of ecological flow; assigns the weight to each index by analytic hierarchyprocess (AHP); and evaluates the different schemes for reservoirs in Xijiang River Basin underfour loss of regulation capacity scenarios with the fuzzy optimization model, non-negative matrixfactorization algorithm and AGA-based projection pursuit clustering model. The results show thatthere is a slight difference in the advantages and disadvantages of the schemes evaluated bydifferent methods, and the recommended schemes under different scenarios are given by integratingthe three methods.