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Chi Yao
School of Civil Engineering and Architecture Nanchang University Nanchang People's Republic of China

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Research article
Published: 18 March 2021 in Energy Science & Engineering
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Discrete fracture network (DFN) is an effective means of describing the coupling of heat flow in an underground fractured rock mass. In this paper, an improved DFN is proposed by introducing the correlation function of fracture trace length and aperture, which is more consistent with the real fracture data. Next, based on the improved model, the influence of fracture roughness on the fluid flow and heat transmission was evaluated, and the relationship between the fracture aperture and the joint roughness coefficient (JRC) is established. Finally, based on the exponential function between confining pressure and aperture, the influence of confining pressure on the heat‐flow coupling process is considered in the improved model. Besides, the reliability of the model was verified by comparing with the analytical solution of the two‐dimensional single‐fracture heat‐flow coupling problem. The results show that under the same conditions, considering the correlation between the geometric parameters of the fracture, the seepage and heat transfer rates of the model increased, the outlet boundary flow reached the maximum value, and the average outlet temperature dropped rapidly. However, the fracture roughness reduces the outlet flow rate and the decline rate of average temperature. The confining pressure will lead to a decrease of about 3.5% in the outlet flow of the model, which is consistent with the seepage law in practical engineering. The model presented in this paper is an effective supplement to the two‐dimensional fracture network heat‐flow coupling model and can provide a theoretical basis and a numerical calculation tool for related underground rock mass engineering.

ACS Style

Fan Huang; Chi Yao; Xiaobo Zhang; Ligong Wu; Yulong Shao; Chuangbing Zhou. Effects of fracture parameters and roughness on heat‐flow coupling in rock masses with two‐dimensional fracture networks. Energy Science & Engineering 2021, 9, 1216 -1231.

AMA Style

Fan Huang, Chi Yao, Xiaobo Zhang, Ligong Wu, Yulong Shao, Chuangbing Zhou. Effects of fracture parameters and roughness on heat‐flow coupling in rock masses with two‐dimensional fracture networks. Energy Science & Engineering. 2021; 9 (8):1216-1231.

Chicago/Turabian Style

Fan Huang; Chi Yao; Xiaobo Zhang; Ligong Wu; Yulong Shao; Chuangbing Zhou. 2021. "Effects of fracture parameters and roughness on heat‐flow coupling in rock masses with two‐dimensional fracture networks." Energy Science & Engineering 9, no. 8: 1216-1231.

Journal article
Published: 05 August 2020 in Applied Mathematical Modelling
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Connectivity evaluation of fracture networks is important in the design, assessment, and development of reservoirs in various engineering applications involving geothermal exploitation and the petroleum industry. By employing nonhomogeneous Poisson distribution and annealing arithmetic, this study generates fracture networks that fit well with actual outcrop fracture data. Based on Allard's definition of the connectivity index, a weighted factor is introduced, and an extended connectivity evaluation method is proposed to consider the effects of the aperture and its correlation with trace length. The results of the analysis show that the extended method improves the accuracy and reliability of connectivity evaluation compared with the traditional method. Moreover, the extended method is effective and accurate at predicting potential preferential flow paths in a practical example of the Dragon and Tiger Mountain (Jiangxi, China), and can better show the anisotropy with a change in the aperture. Hence, the proposed method extends the function of connectivity analysis and can benefit well location optimization in geothermal or petroleum exploration.

ACS Style

Fan Huang; Chi Yao; Jianhua Yang; Chen He; Yulong Shao; Chuangbing Zhou. Connectivity evaluation of fracture networks considering the correlation between trace length and aperture. Applied Mathematical Modelling 2020, 88, 870 -887.

AMA Style

Fan Huang, Chi Yao, Jianhua Yang, Chen He, Yulong Shao, Chuangbing Zhou. Connectivity evaluation of fracture networks considering the correlation between trace length and aperture. Applied Mathematical Modelling. 2020; 88 ():870-887.

Chicago/Turabian Style

Fan Huang; Chi Yao; Jianhua Yang; Chen He; Yulong Shao; Chuangbing Zhou. 2020. "Connectivity evaluation of fracture networks considering the correlation between trace length and aperture." Applied Mathematical Modelling 88, no. : 870-887.

Original paper
Published: 29 June 2020 in Bulletin of Engineering Geology and the Environment
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The Revised Universal Soil Loss Equation (RUSLE) models are most widely used for quantitative prediction of soil erosion. However, these models have many shortcomings. For example, the annual total rainfall is often adopted, ignoring the inhomogeneity of seasonal rainfall. The adopted vegetation coverage indexes (VCIs) are usually the annual average vegetation coverage or VCIs obtained by monitoring on a specific day, ignoring the seasonal changes in VCIs during the year. In addition, the impact of slope on the conservation practices factor is not considered. To overcome these problem, this study aims to propose a seasonal and slope factor-based RUSLE (SUSLE) model that considers the seasonal changes in rainfall and VCIs and the effect of slope on the conservation practices factor. Based on GIS and remote sensing, the quantitative prediction of soil erosion in Ningdu County, Jiangxi Province, in 2017 is taken as a case study. The traditional RUSLE model and the proposed SUSLE model are analyzed and compared. Results show that the overall distribution characteristics of soil erosion in the two models are similar that the SUSLE model is more consistent than the RUSLE model in all erosion levels and that the prediction performances of the SUSLE model in the very low, moderate, and high erosion levels are better than those of the RUSLE model. The distribution characteristics of soil erosion in different periods and the relationships between soil erosion and environmental factors (e.g., slope and land use) under the SUSLE model are discussed. The results show that the maximum erosion area occurred in spring and the minimum area in autumn; the soil erosion amount on slopes of 8~25° reached 65.14% of the total amount; bare grassland and cultivated land are the main land cover types impacted by soil erosion in Ningdu County.

ACS Style

Faming Huang; Jiawu Chen; Chi Yao; Zhilu Chang; Qinghui Jiang; Shu Li; Zizheng Guo. SUSLE: a slope and seasonal rainfall-based RUSLE model for regional quantitative prediction of soil erosion. Bulletin of Engineering Geology and the Environment 2020, 79, 5213 -5228.

AMA Style

Faming Huang, Jiawu Chen, Chi Yao, Zhilu Chang, Qinghui Jiang, Shu Li, Zizheng Guo. SUSLE: a slope and seasonal rainfall-based RUSLE model for regional quantitative prediction of soil erosion. Bulletin of Engineering Geology and the Environment. 2020; 79 (10):5213-5228.

Chicago/Turabian Style

Faming Huang; Jiawu Chen; Chi Yao; Zhilu Chang; Qinghui Jiang; Shu Li; Zizheng Guo. 2020. "SUSLE: a slope and seasonal rainfall-based RUSLE model for regional quantitative prediction of soil erosion." Bulletin of Engineering Geology and the Environment 79, no. 10: 5213-5228.

Journal article
Published: 08 June 2020 in ISPRS International Journal of Geo-Information
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Soil erosion (SE) provides slide mass sources for landslide formation, and reflects long-term rainfall erosion destruction of landslides. Therefore, it is possible to obtain more reliable landslide susceptibility prediction results by introducing SE as a geology and hydrology-related predisposing factor. The Ningdu County of China is taken as a research area. Firstly, 446 landslides are obtained through government disaster survey reports. Secondly, the SE amount in Ningdu County is calculated and nine other conventional predisposing factors are obtained under both 30 m and 60 m grid resolutions to determine the effects of SE on landslide susceptibility prediction. Thirdly, four types of machine-learning predictors with 30 m and 60 m grid resolutions—C5.0 decision tree (C5.0 DT), logistic regression (LR), multilayer perceptron (MLP) and support vector machine (SVM)—are applied to construct the landslide susceptibility prediction models considering the SE factor as SE-C5.0 DT, SE-LR, SE-MLP and SE-SVM models; C5.0 DT, LR, MLP and SVM models with no SE are also used for comparisons. Finally, the area under receiver operating feature curve is used to verify the prediction accuracy of these models, and the relative importance of all the 10 predisposing factors is ranked. The results indicate that: (1) SE factor plays the most important role in landslide susceptibility prediction among all 10 predisposing factors under both 30 m and 60 m resolutions; (2) the SE-based models have more accurate landslide susceptibility prediction than the single models with no SE factor; (3) all the models with 30 m resolutions have higher landslide susceptibility prediction accuracy than those with 60 m resolutions; and (4) the C5.0 DT and SVM models show higher landslide susceptibility prediction performance than the MLP and LR models.

ACS Style

Faming Huang; Jiawu Chen; Zhen Du; Chi Yao; Jinsong Huang; Qinghui Jiang; Zhilu Chang; Shu Li. Landslide Susceptibility Prediction Considering Regional Soil Erosion Based on Machine-Learning Models. ISPRS International Journal of Geo-Information 2020, 9, 377 .

AMA Style

Faming Huang, Jiawu Chen, Zhen Du, Chi Yao, Jinsong Huang, Qinghui Jiang, Zhilu Chang, Shu Li. Landslide Susceptibility Prediction Considering Regional Soil Erosion Based on Machine-Learning Models. ISPRS International Journal of Geo-Information. 2020; 9 (6):377.

Chicago/Turabian Style

Faming Huang; Jiawu Chen; Zhen Du; Chi Yao; Jinsong Huang; Qinghui Jiang; Zhilu Chang; Shu Li. 2020. "Landslide Susceptibility Prediction Considering Regional Soil Erosion Based on Machine-Learning Models." ISPRS International Journal of Geo-Information 9, no. 6: 377.

Research article
Published: 20 March 2020 in Energy Science & Engineering
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Connectivity is an effective indicator to describe the flow paths and mechanical behavior of reservoir fractured rock masses. The connectivity evaluation of fracture networks plays an important role in the design, assessment, and development of reservoirs in several important engineering applications, such as geothermal recovery and petroleum industry. Based on Allard's definition of a connectivity index, a 3D connectivity evaluation method is proposed in this study by building the connectivity functions of the supports. Meanwhile, different connectivity functions are built for different situations. In addition, a convex polygon is used to simulate the fracture to make the fracture network as real as possible. The accuracy of the generated fracture network was verified by comparing three parameters of fracture, and the results showed that the relative error was less than 5%. Some examples in the Ordos Basin, China, are given to verify the correctness of the program and method. Analysis results show that the 3D method is more realistic than the 2D connectivity evaluation, and the connectivity field of the fracture network is more reliable in the 3D method. Moreover, the proposed method can show the potential preferential flow path in a stereoscopic manner and thus greatly extends the function of connectivity analysis. This method provides important information for the prediction of paths and the evaluation of the connectivity of the fracture network and is important in evaluating the optimal location of geothermal recovery and petroleum industry.

ACS Style

Fan Huang; Chi Yao; Xiaobo Zhang; Yulong Shao; Chen He; Chuangbing Zhou. Connectivity evaluation for three‐dimensional fracture network in support‐based model: A case study in the Ordos Basin, China. Energy Science & Engineering 2020, 8, 2492 -2510.

AMA Style

Fan Huang, Chi Yao, Xiaobo Zhang, Yulong Shao, Chen He, Chuangbing Zhou. Connectivity evaluation for three‐dimensional fracture network in support‐based model: A case study in the Ordos Basin, China. Energy Science & Engineering. 2020; 8 (7):2492-2510.

Chicago/Turabian Style

Fan Huang; Chi Yao; Xiaobo Zhang; Yulong Shao; Chen He; Chuangbing Zhou. 2020. "Connectivity evaluation for three‐dimensional fracture network in support‐based model: A case study in the Ordos Basin, China." Energy Science & Engineering 8, no. 7: 2492-2510.

Journal article
Published: 04 November 2018 in Energies
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The research on the factors of heat recovery performance of Enhanced Geothermal Systems (EGS) is an important issue, especially in the well position optimization in EGS, because it can maximize the economic benefits of EGS. Based on the three-dimensional thermo and hydro (TH) single-fracture model, a flow field in the EGS is added to the model, the thermal energy mining of the EGS thermal reservoir is realized through the double well and better study of the impact of regional flow on EGS well placement. To verify the reliability of the three-dimensional numerical model, the comparison between the two-dimensional single fracture model and the single fracture analytical model is performed under the same conditions, and it is found that there is a good agreement between the numerical and the analytical solutions. The influence of the direction of regional flow on the thermal recovery performance of EGS is studied, and the operating lifetime, power generation and heat production rate of the system are used as the evaluation indicators. It is found that there are two stagnation points in the flow field under regional flow conditions, and the stagnation point position changes regularly with regional flow direction. The direction of regional flow has a great influence on the heat extraction ratio and service lifetime of the geothermal system, the layout of the double well must take into account the regional flow. When only considered the influence of regional flow on EGS, after 50 years of EGS operation, the production well temperature and system operating lifetime increase with the increase of β (the angle between the direction of the regional flow and the line connecting the centers of the two wells). When it has regional flow, the greater the well spacing, the greater the temperature of the production well, but when the well spacing increases to a certain value, the well spacing will not affect the temperature of the production well.

ACS Style

Chi Yao; Yulong Shao; Jianhua Yang. Numerical Investigation on the Influence of Areal Flow on EGS Thermal Exploitation Based on the 3-D T-H Single Fracture Model. Energies 2018, 11, 3026 .

AMA Style

Chi Yao, Yulong Shao, Jianhua Yang. Numerical Investigation on the Influence of Areal Flow on EGS Thermal Exploitation Based on the 3-D T-H Single Fracture Model. Energies. 2018; 11 (11):3026.

Chicago/Turabian Style

Chi Yao; Yulong Shao; Jianhua Yang. 2018. "Numerical Investigation on the Influence of Areal Flow on EGS Thermal Exploitation Based on the 3-D T-H Single Fracture Model." Energies 11, no. 11: 3026.

Research article
Published: 01 August 2018 in Advances in Civil Engineering
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Anisotropy in strength and deformation of rock mass induced by bedding planes and interlayered structures is a vital problem in rock mechanics and rock engineering. The modified rigid block spring method (RBSM), initially proposed for modeling of isotropic rock, is extended to study the failure process of interlayered rocks under compression with different confining pressures. The modified rigid block spring method is used to simulate the initiation and propagation of microcracks. The Mohr–Coulomb criterion is employed to determine shear failure events and the tensile strength criterion for tensile failure events. Rock materials are replaced by an assembly of Voronoi-based polygonal blocks. To explicitly simulate structural planes and for automatic mesh generation, a multistep point insertion procedure is proposed. A typical experiment on interlayered rocks in literature is simulated using the proposed model. Effects of the orientation of bedding planes with regard to the loading direction on the failure mechanism and strength anisotropy are emphasized. Results indicate that the modified RBSM model succeeds in capturing main failure mechanisms and strength anisotropy induced by interlayered structures and different confining pressures.

ACS Style

Chi Yao; Sizhi Zeng; Jianhua Yang. Failure Process Simulation of Interlayered Rocks under Compression. Advances in Civil Engineering 2018, 2018, 1 -13.

AMA Style

Chi Yao, Sizhi Zeng, Jianhua Yang. Failure Process Simulation of Interlayered Rocks under Compression. Advances in Civil Engineering. 2018; 2018 ():1-13.

Chicago/Turabian Style

Chi Yao; Sizhi Zeng; Jianhua Yang. 2018. "Failure Process Simulation of Interlayered Rocks under Compression." Advances in Civil Engineering 2018, no. : 1-13.

Articles
Published: 27 September 2017 in European Journal of Environmental and Civil Engineering
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By employing the improved rigid block spring method, the failure process of a sandstone example containing a single open fissure under uniaxial compression is modelled. In this method, the intact rock is considered as an assemblage of rigid polygonal blocks. Macro mechanical behaviours are governed by mechanical properties of interfaces between two neighbouring blocks. In the local scale on interfaces, both tensile splitting failure and shearing sliding failure are considered. Micro properties are obtained by a calibration procedure against the stress–strain curve of intact rock under uniaxial compression in the lab. Influences of fissure inclination and length on the uniaxial compression strength (UCS) and failure modes are discussed. Comparisons between numerical simulations and laboratory tests are presented. The growth process of micro-cracks is studied and the mechanism of micro-crack propagation is studied through analysis on the displacement evolution. Some conclusions are drawn: numerical results generally agree well with those from lab tests; the UCS of fissured rock is lower than the intact one; the UCS first goes down then goes up as inclination increases, but decreases gradually as fissure length increases; the micro failure modes are governed mainly by tensile splitting failures.

ACS Style

Bin Wang; Chi Yao; Jianhua Yang; Shuihua Jiang. Numerical simulation of macro-meso mechanical behaviours of sandstone containing a single open fissure under uniaxial compression. European Journal of Environmental and Civil Engineering 2017, 22, s99 -s113.

AMA Style

Bin Wang, Chi Yao, Jianhua Yang, Shuihua Jiang. Numerical simulation of macro-meso mechanical behaviours of sandstone containing a single open fissure under uniaxial compression. European Journal of Environmental and Civil Engineering. 2017; 22 (sup1):s99-s113.

Chicago/Turabian Style

Bin Wang; Chi Yao; Jianhua Yang; Shuihua Jiang. 2017. "Numerical simulation of macro-meso mechanical behaviours of sandstone containing a single open fissure under uniaxial compression." European Journal of Environmental and Civil Engineering 22, no. sup1: s99-s113.

Journal article
Published: 01 July 2017 in Applied Mathematical Modelling
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ACS Style

Shui-Hua Jiang; Jinsong Huang; Chi Yao; Jianhua Yang. Quantitative risk assessment of slope failure in 2-D spatially variable soils by limit equilibrium method. Applied Mathematical Modelling 2017, 47, 710 -725.

AMA Style

Shui-Hua Jiang, Jinsong Huang, Chi Yao, Jianhua Yang. Quantitative risk assessment of slope failure in 2-D spatially variable soils by limit equilibrium method. Applied Mathematical Modelling. 2017; 47 ():710-725.

Chicago/Turabian Style

Shui-Hua Jiang; Jinsong Huang; Chi Yao; Jianhua Yang. 2017. "Quantitative risk assessment of slope failure in 2-D spatially variable soils by limit equilibrium method." Applied Mathematical Modelling 47, no. : 710-725.

Journal article
Published: 01 May 2011 in Advanced Materials Research
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The mechanical characteristics of jointed rocks are mainly controlled by geometrical features of intermittent joints. The failure mechanism and shear behavior of discontinuous joints are simulated by series of direct shear tests using the particle flow code (PFC2D). The effects of joint persistence, separation and azimuth angle on the failure strength of jointed rock are studied in detail. The results shows that peak shear strength can be considered as a function of the geometrical parameters, which is in a reasonable accordance with other experimental results. Meanwhile, as for failure mechanism, joint separation and azimuth angle are especially discussed, and specific damage patterns are presented as well.

ACS Style

Bin Wang; Qing Hui Jiang; Chi Yao; Tao Xie. Numerical Analysis on Failure Mechanism of Intermittent Joints. Advanced Materials Research 2011, 255-260, 113 -117.

AMA Style

Bin Wang, Qing Hui Jiang, Chi Yao, Tao Xie. Numerical Analysis on Failure Mechanism of Intermittent Joints. Advanced Materials Research. 2011; 255-260 ():113-117.

Chicago/Turabian Style

Bin Wang; Qing Hui Jiang; Chi Yao; Tao Xie. 2011. "Numerical Analysis on Failure Mechanism of Intermittent Joints." Advanced Materials Research 255-260, no. : 113-117.