scholarly journals Penetration Grouting Mechanism of Time-Dependent Power-Law Fluid for Reinforcing Loose Gravel Soil

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1391
Author(s):  
Tingting Guo ◽  
Zhiwei Zhang ◽  
Zhiquan Yang ◽  
Yingyan Zhu ◽  
Yi Yang ◽  
...  
Keyword(s):  
Numerical Calculation ◽  
Numerical Simulations ◽  
Power Law ◽  
Three Dimensional ◽  
Time Dependent ◽  
Rheological Parameters ◽  
Power Law Fluid ◽  
Dependent Behavior ◽  
Gravel Soil ◽  
Penetration Grouting

The time-dependent behavior of power-law fluid has a significant influence on the grouting effects of reinforcing loose gravel soil. In this paper, based on basic rheological equations and the time-dependent behavior of rheological parameters (consistency coefficient and rheological index), rheological equations and penetration equations of time-dependent power-law fluid are proposed. Its penetration grouting diffusion mechanism for reinforcing loose gravel soil was then theoretically induced. A set of indoor experimental devices for simulating penetration grouting was designed to simulate the penetration grouting of power-law fluid with different time-dependent behaviors for reinforcing loose gravel soil. Then, relying on the COMSOL Multiphysics platform and Darcy’s law, three-dimensional numerical calculation programs for this mechanism were obtained using secondary-development programming technology. Thus, the numerical simulations of the penetration grouting process of power-law fluid with different time-dependent behaviors for reinforcing loose gravel soil were carried out. This theoretical mechanism was validated by comparing results from theoretical analyses, indoor experiments, and numerical simulations. Research results show that the three-dimensional numerical calculation programs can successfully simulate the penetration diffusion patterns of a time-dependent power-law fluid in loose gravel soil. The theoretical calculation values and numerical simulation values of the diffusion radius obtained from this mechanism are closer to indoor experimental values than those obtained from the penetration grouting diffusion theory of power-law fluid without considering time-dependent behavior. This mechanism can better reflect the penetration grouting diffusion laws of a power-law fluid in loose gravel soil than the theory, which can provide theoretical support and guidance for practical grouting construction.

scholarly journals Study on Penetration Grouting Mechanism Based on Newton Fluid of Time-Dependent Behavior of Rheological Parameters

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Yi Ding ◽  
Zhi-Quan Yang ◽  
Yi Yang ◽  
Ying-Yan Zhu ◽  
Yong-Fa Guo ◽  
...  
Keyword(s):  
Theoretical Basis ◽  
Time Dependent ◽  
Theoretical Research ◽  
Rheological Parameters ◽  
Rheological Equation ◽  
Actual Measurement ◽  
Whole Process ◽  
Dependent Behavior ◽  
Fluid Penetration ◽  
Penetration Grouting

Grouting mechanism is one of the important factors on the grouting effects of practical projects. At present, the vast majority of Newton fluid penetration grouting mechanisms are considering that the viscosity of Newton fluid during the grouting whole process was constant, so the theoretical diffusion radius calculated by them is far greater than the actual measurements in the grouting engineering. Carrying out theoretical analysis and experimental research, the rheological equation and seepage motion equation for Newton fluid of time-dependent behavior of rheological parameters were established; then, the penetration grouting mechanism of them was deduced. What is more, they were validated by means of designing the grouting verifying experiments. Experiment results show that the theoretical diffusion radius calculated by the formula of diffusion radius of penetration grouting mechanism based on Newton fluid of time-dependent behavior of rheological parameters was in accordance with the change regulation of the actual measurement diffusion radius by grouting experiments. Their difference within the range of 15% is far less than about 80% change between the theoretical diffusion radius calculated by the Maag formula and the actual measurement radius. In general, it can reflect the grout infiltration laws that Newton fluid changes with time. Therefore, research achievements may not only be able to provide a strong theoretical basis for perfecting the penetration grouting mechanism but also play a reference guiding role for the theoretical research, design, and construction in the grouting technique.

Flow Mixing Enhancement from Balloon Pulsations in an Intravenous Oxygenator

2004 ◽  
Vol 127 (3) ◽  
pp. 400-415 ◽  
Author(s):  
Amador M. Guzmán ◽  
Rodrigo A. Escobar ◽  
Cristina H. Amon
Keyword(s):  
Numerical Simulations ◽  
Oxygen Transfer ◽  
Fiber Bundle ◽  
Transfer Rate ◽  
Oxygen Transfer Rate ◽  
Three Dimensional ◽  
Time Dependent ◽  
Fiber Placement ◽  
Flow Mixing ◽  
Dependent Flow

Computational investigations of flow mixing and oxygen transfer characteristics in an intravenous membrane oxygenator (IMO) are performed by direct numerical simulations of the conservation of mass, momentum, and species equations. Three-dimensional computational models are developed to investigate flow-mixing and oxygen-transfer characteristics for stationary and pulsating balloons, using the spectral element method. For a stationary balloon, the effect of the fiber placement within the fiber bundle and the number of fiber rings is investigated. In a pulsating balloon, the flow mixing characteristics are determined and the oxygen transfer rate is evaluated. For a stationary balloon, numerical simulations show two well-defined flow patterns that depend on the region of the IMO device. Successive increases of the Reynolds number raise the longitudinal velocity without creating secondary flow. This characteristic is not affected by staggered or non-staggered fiber placement within the fiber bundle. For a pulsating balloon, the flow mixing is enhanced by generating a three-dimensional time-dependent flow characterized by oscillatory radial, pulsatile longitudinal, and both oscillatory and random tangential velocities. This three-dimensional flow increases the flow mixing due to an active time-dependent secondary flow, particularly around the fibers. Analytical models show the fiber bundle placement effect on the pressure gradient and flow pattern. The oxygen transport from the fiber surface to the mean flow is due to a dominant radial diffusion mechanism, for the stationary balloon. The oxygen transfer rate reaches an asymptotic behavior at relatively low Reynolds numbers. For a pulsating balloon, the time-dependent oxygen-concentration field resembles the oscillatory and wavy nature of the time-dependent flow. Sherwood number evaluations demonstrate that balloon pulsations enhance the oxygen transfer rate, even for smaller flow rates.

scholarly journals Inversion of flow Measurements for Stress and Rheological Parameters in a Valley Glacier

1973 ◽  
Vol 12 (64) ◽  
pp. 19-44
Author(s):  
Charles F. Raymond
Keyword(s):  
Shear Stress ◽  
Power Law ◽  
Measurement Errors ◽  
Effective Viscosity ◽  
Three Dimensional ◽  
Rheological Parameters ◽  
Mean Stress ◽  
Flow Measurements ◽  
Anomalous Zone ◽  
Flow Law

AbstractMethods are developed for determining the distributions of stress and effective viscosity in a glacier, under the assumptions: the ice is quasi-viscous, the flow is time independent, and acceleration forces are negligible. Measurements of the three-dimensional distribution of velocity are needed for their application. The differential equations of mechanical equilibrium, expressed in terms of viscosity, strain-rate components, mean stress, and their gradients, are viewed as equations to be solved for viscosity and mean stress subject to boundary conditions at the free upper surface. For certain rectilinear flow patterns, unique distributions of stress and effective viscosity can always be derived. For more complicated flow this is not necessarily so. However, it is still possible to choose the best values of rheological parameters in any trial flow law based on the requirement that the residuals to the equations of equilibrium be minimized in a mean-square sense. The techniques are applied to measurements of internal deformation made in nine bore holes on the Athabasca Glacier. At the center line the magnitude of the surface-parallel shear stress increases with depth more slowly than would be expected from a standard shape factor correction or the theoretical distribution of Nye. Correspondingly the lateral distribution of lateral shear stress shows the opposite relationships. In the lower one- to two-thirds of the depth corresponding to a range in effective stress from about 0.5 to 1.2 bars, the gross rheology of the ice is not distinguishably different from the experimentally determined flow law of Glen (n = 4.2, T = 0.02° C) as generalized by Nye. The results do not support the conclusion that the effective viscosity is higher than would be expected from Glen’s experiments as indicated by the more limited measurements of Paterson and Savage. Power-law parameters derived for the different bore holes considered separately show a spread, which suggests some rheological inhomogeneity. However, no definite conclusions can be drawn, because of direct measurement errors at the bore holes and less definable uncertainty in the interpolated distribution of velocity between the holes. The upper one- to two-thirds of the glacier constitutes an anomalous zone in which there is either a strong effect from a complex distribution of stress arising from longitudinal stress gradients or more complicated rheology than in a homogeneous power-law material.

scholarly journals A Nonlinear Creep Damage Model Considering the Effect of Dry-Wet Cycles of Rocks on Reservoir Bank Slopes

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2396
Author(s):  
Xingang Wang ◽  
Baoqin Lian ◽  
Wenkai Feng
Keyword(s):  
Three Dimensional ◽  
Influential Factor ◽  
Time Dependent ◽  
Secondary Development ◽  
Nonlinear Creep ◽  
Test Results ◽  
Creep Tests ◽  
New Model ◽  
Dependent Behavior ◽  
Rock Creep

Water has a crucial effect on the time-dependent behavior of rocks. The long-term cyclical fluctuations of reservoir water level lead to dry–wet (DW) cycles of rocks on reservoir bank slopes, making this influential factor more complex. To deeply understand the time-dependent behavior of rocks under DW cycles, argillite from the reservoir bank slope of Longtan Hydropower Station was used to perform a series of triaxial creep tests. Subsequently, based on analysis of creep test results after different DW cycles, a damage nonlinear Burgers viscoelastic-plastic (DNBVP) model considering the effect of saturation–dehydration cycles was proposed by introducing a nonlinear viscoplastic body and a damage variable describing DW cycles. Then, the three-dimensional creep equations of the new model were derived and its creep parameters were identified. Comparison between the theoretical curves and the test results shows that the theoretical curves of the DNBVP model were able to describe rock creep tests results after different DW cycles. Furthermore, by comparing classical creep models with the proposed model, it was found that the DNBVP model can accurately reflect the nonlinear characteristics of rocks at the accelerated creep stage. Finally, the sensitivity of the DNBVP model was analyzed and discussed, and three-dimensional central difference expressions necessary for secondary development of the new model were also derived in detail. The proposed new model with secondary development may provide a basis for improving the geotechnical design of reservoir bank slopes and the control of reservoir bank landslides.

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