The Experts below are selected from a list of 15780 Experts worldwide ranked by ideXlab platform
Yujing Jiang - One of the best experts on this subject based on the ideXlab platform.
-
influences of Hydraulic Gradient surface roughness intersecting angle and scale effect on nonlinear flow behavior at single fracture intersections
Journal of Hydrology, 2016Co-Authors: Richeng Liu, Yujing JiangAbstract:Summary Fluid flow tests were conducted on two crossed fracture models for which the geometries of fracture segments and intersections were measured by utilizing a visualization technique using a CCD (charged coupled device) camera. Numerical simulations by solving the Navier–Stokes equations were performed to characterize the fluid flow at fracture intersections. The roles of Hydraulic Gradient, surface roughness, intersecting angle, and scale effect in the nonlinear fluid flow behavior through single fracture intersections were investigated. The simulation results of flow rate agreed well with the experimental results for both models. The experimental and simulation results showed that with the increment of the Hydraulic Gradient, the ratio of the flow rate to the Hydraulic Gradient, Q / J , decreases and the relative difference of Q / J between the calculation results employing the Navier–Stokes equations and the cubic law, δ , increases. When taking into account the fracture surface roughness quantified by Z 2 ranging 0–0.42 for J = 1, the value of δ would increase by 0–10.3%. The influences of the intersecting angle on the normalized flow rate that represents the ratio of the flow rate in a segment to the total flow rate, R a , and the ratio of the Hydraulic aperture to the mechanical aperture, e / E , are negligible when J −3 , whereas their values change significantly when J > 10 −2 . Based on the regression analysis on simulation results, a mathematical expression was proposed to quantify e / E , involving variables of J and R r , where R r is the radius of truncating circles centered at an intersection. For E / R r > 10 −2 , e / E varies significantly and the scale of model has large impacts on the nonlinear flow behavior through intersections, while for E / R r −3 , the scale effect is negligibly small. Finally, a necessary condition to apply the cubic law to fluid flow through fracture intersections is suggested as J −3 , E / R r −3 , and Z 2 = 0.
-
critical Hydraulic Gradient for nonlinear flow through rock fracture networks the roles of aperture surface roughness and number of intersections
Advances in Water Resources, 2016Co-Authors: Richeng Liu, Yujing JiangAbstract:Transition of fluid flow from the linear to the nonlinear regime has been confirmed in single rock fractures when the Reynolds number (Re) exceeds some critical values, yet the criterion for such a transition in discrete fracture networks (DFNs) has received little attention. This study conducted flow tests on crossed fracture models with a single intersection and performed numerical simulations on fluid flow through DFNs of various geometric characteristics. The roles of aperture, surface roughness, and number of intersections of fractures on the variation of the critical Hydraulic Gradient (Jc) for the onset of nonlinear flow through DFNs were systematically investigated. The results showed that the relationship between Hydraulic Gradient (J) and flow rate can be well quantified by Forchheimer's law; when J drops below Jc, it reduces to the widely used cubic law, by diminishing the nonlinear term. Larger apertures, rougher fracture surfaces, and a greater number of intersections in a DFN would result in the onset of nonlinear flow at a lower Jc. Mathematical expressions of Jc and the coefficients involved in Forchheimer's law were developed based on multi-variable regressions of simulation results, which can help to choose proper governing equations when solving problems associated with fluid flow in fracture networks.
Richeng Liu - One of the best experts on this subject based on the ideXlab platform.
-
influences of Hydraulic Gradient surface roughness intersecting angle and scale effect on nonlinear flow behavior at single fracture intersections
Journal of Hydrology, 2016Co-Authors: Richeng Liu, Yujing JiangAbstract:Summary Fluid flow tests were conducted on two crossed fracture models for which the geometries of fracture segments and intersections were measured by utilizing a visualization technique using a CCD (charged coupled device) camera. Numerical simulations by solving the Navier–Stokes equations were performed to characterize the fluid flow at fracture intersections. The roles of Hydraulic Gradient, surface roughness, intersecting angle, and scale effect in the nonlinear fluid flow behavior through single fracture intersections were investigated. The simulation results of flow rate agreed well with the experimental results for both models. The experimental and simulation results showed that with the increment of the Hydraulic Gradient, the ratio of the flow rate to the Hydraulic Gradient, Q / J , decreases and the relative difference of Q / J between the calculation results employing the Navier–Stokes equations and the cubic law, δ , increases. When taking into account the fracture surface roughness quantified by Z 2 ranging 0–0.42 for J = 1, the value of δ would increase by 0–10.3%. The influences of the intersecting angle on the normalized flow rate that represents the ratio of the flow rate in a segment to the total flow rate, R a , and the ratio of the Hydraulic aperture to the mechanical aperture, e / E , are negligible when J −3 , whereas their values change significantly when J > 10 −2 . Based on the regression analysis on simulation results, a mathematical expression was proposed to quantify e / E , involving variables of J and R r , where R r is the radius of truncating circles centered at an intersection. For E / R r > 10 −2 , e / E varies significantly and the scale of model has large impacts on the nonlinear flow behavior through intersections, while for E / R r −3 , the scale effect is negligibly small. Finally, a necessary condition to apply the cubic law to fluid flow through fracture intersections is suggested as J −3 , E / R r −3 , and Z 2 = 0.
-
critical Hydraulic Gradient for nonlinear flow through rock fracture networks the roles of aperture surface roughness and number of intersections
Advances in Water Resources, 2016Co-Authors: Richeng Liu, Yujing JiangAbstract:Transition of fluid flow from the linear to the nonlinear regime has been confirmed in single rock fractures when the Reynolds number (Re) exceeds some critical values, yet the criterion for such a transition in discrete fracture networks (DFNs) has received little attention. This study conducted flow tests on crossed fracture models with a single intersection and performed numerical simulations on fluid flow through DFNs of various geometric characteristics. The roles of aperture, surface roughness, and number of intersections of fractures on the variation of the critical Hydraulic Gradient (Jc) for the onset of nonlinear flow through DFNs were systematically investigated. The results showed that the relationship between Hydraulic Gradient (J) and flow rate can be well quantified by Forchheimer's law; when J drops below Jc, it reduces to the widely used cubic law, by diminishing the nonlinear term. Larger apertures, rougher fracture surfaces, and a greater number of intersections in a DFN would result in the onset of nonlinear flow at a lower Jc. Mathematical expressions of Jc and the coefficients involved in Forchheimer's law were developed based on multi-variable regressions of simulation results, which can help to choose proper governing equations when solving problems associated with fluid flow in fracture networks.
Hongzhong Li - One of the best experts on this subject based on the ideXlab platform.
-
investigation of 3d deformation of transparent soil around a laterally loaded pile based on a Hydraulic Gradient model test
Journal of building engineering, 2020Co-Authors: Bingxiang Yuan, Lei Xiong, S P Pradhan, Hongzhong LiAbstract:Abstract Based on the fact that natural soil and transparent soil have similar geotechnical properties, this paper describes a device used in Hydraulic Gradient tests to measure the displacement of transparent soil. The theory of using seepage force to increase the effective self-weight stress of soil is employed to simulate the soil behavior around a laterally loaded pile under high stress field. In order to obtain the 3D displacement of internal soil around a laterally loaded pile, transparent soil is firstly irradiated by lasers. Then, using Particle Image Velocimetry technology, 2D displacements of soil are obtained and restructured, revealing 3D displacement of soil around a laterally loaded pile and verifying the feasibility of the experiment in measuring soil displacement. Additionally, the 3D deformation characteristics of soil around a laterally loaded pile are analyzed. Results show that the displacement of the soil around the pile mainly occurs in the shallow soil layer and that the direction of displacement is oblique-upward along the loading direction. What's more, with an increase in distance from the pile edge, as well as with an increase in the depth, the displacement magnitude gradually decreases.
Weidong Zhao - One of the best experts on this subject based on the ideXlab platform.
-
experimental study of turbulent unconfined groundwater flow in a single fracture
Journal of Hydrology, 2005Co-Authors: Weidong ZhaoAbstract:Laboratory experiments have been carried out to study groundwater flow in a single fracture under the conditions of different surface roughness and apertures. We found that the Gradient of the Reynolds number versus the average velocity in a single fracture was almost independent of the change of fracture surface roughness, and it decreased when the aperture decreased under the same surface roughness. The experimental results showed that the average flow velocity (V) could be approximated by an empirical exponential function of the Hydraulic Gradient (I), and the power index of the exponential function was close to 0.5 when the Hydraulic Gradient is around 0.003 to 0.02. Such a V–I relationship indicated a non-Darcian turbulent flow in the fracture even though the Reynolds number was relatively low (between 333.26 and 1413.62). This finding supports the claims of non-Darcian flow observed in fractures by many recent studies under relatively fast flow condition but disagreed with the Darcian flow and local cubic law assumptions used in some previous studies. q 2005 Elsevier B.V. All rights reserved.
Bingxiang Yuan - One of the best experts on this subject based on the ideXlab platform.
-
investigation of 3d deformation of transparent soil around a laterally loaded pile based on a Hydraulic Gradient model test
Journal of building engineering, 2020Co-Authors: Bingxiang Yuan, Lei Xiong, S P Pradhan, Hongzhong LiAbstract:Abstract Based on the fact that natural soil and transparent soil have similar geotechnical properties, this paper describes a device used in Hydraulic Gradient tests to measure the displacement of transparent soil. The theory of using seepage force to increase the effective self-weight stress of soil is employed to simulate the soil behavior around a laterally loaded pile under high stress field. In order to obtain the 3D displacement of internal soil around a laterally loaded pile, transparent soil is firstly irradiated by lasers. Then, using Particle Image Velocimetry technology, 2D displacements of soil are obtained and restructured, revealing 3D displacement of soil around a laterally loaded pile and verifying the feasibility of the experiment in measuring soil displacement. Additionally, the 3D deformation characteristics of soil around a laterally loaded pile are analyzed. Results show that the displacement of the soil around the pile mainly occurs in the shallow soil layer and that the direction of displacement is oblique-upward along the loading direction. What's more, with an increase in distance from the pile edge, as well as with an increase in the depth, the displacement magnitude gradually decreases.
-
a Hydraulic Gradient similitude testing system for studying the responses of a laterally loaded pile and soil deformation
Environmental Earth Sciences, 2016Co-Authors: Bingxiang Yuan, Rui Chen, Jinhui Li, Yixian Wang, Wenwu ChenAbstract:In this study, a newly developed Hydraulic Gradient similitude (HGS) test and the particle image velocimetry (PIV) technique were applied to a laterally loaded pile to simultaneously measure the responses of a laterally loaded pile and sand displacement fields in a high-body force field. A comparison of the stages in the HGS test indicated that the lateral displacement of the loading point was doubled and that the applied load increased by 54 %. These results indicate that the rate of load increase gradually decreases with the increased displacement due to the plastic behavior of the soil. In addition, soil deformation increased as the lateral load increased, the soil behind the pile moved downwards because the resistance of the pile decreased, and the soil near the ground in front of the pile moved upwards because the movement of the pile caused the soil to resist lateral movement. The authors provide an additional model test for saturated soils under hydrostatic conditions (i.e., 1 g) to study the effects of the Hydraulic Gradient on the response of the pile and sand deformation. This comparison indicated that the lateral load in the HGS test was 4.2 times greater than that in the 1 g model test with a displacement of 3.82 mm times the loading point. In addition, the magnitudes of the deflection were smaller than those in the 1 g model test when the self-weight stress was increased 11 times. The passive influence zone in front of the pile in the 1 g model test was 50 % greater than that in the HGS test. In addition, the sand displacement around the pile in the 1 g model test was greater than that in the HGS test. The main reason for the abovementioned results are that the relative stiffness ratio between the soil and pile increased as the Hydraulic Gradient increased. Ultimately, this study shows that the PIV technique can be used to accurately measure soil displacement and represent pile deflection under different body forces. This study increases our understanding of the responses of soil to a laterally loaded pile and of soil deformation in a high-body force field. The results of this study demonstrate that the developed HGS device and the combination of the HGS and PIV techniques are suitable for solving soil–pile interaction problems.
