scholarly journals Research on Permeability Coefficient of Heterogeneous Geomaterials Based on Digital Images

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Bowen Liu ◽  
Junbin Chen ◽  
Xinpin Ding
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Theoretical Calculation ◽  
Permeability Coefficient ◽  
Confining Pressure ◽  
Experimental Result ◽  
Equivalent Permeability ◽  
Permeability Coefficients ◽  
Heterogeneous Rock ◽  
The Relationship

According to the relationship between permeability and porosity of geotechnical materials, a finite element model representing pore and solid particles is generated randomly according to the porosity of a given finite element calculation model. According to Darcy’s law of flow distribution and steady seepage in the finite element random simulation section, the equivalent permeability coefficients at different porosities are calculated, and the relationship between the equivalent permeability coefficient and the porosity of rock and soil is studied. The results show that the equivalent permeability coefficient is proportional to the porosity with the same pore size. In order to study the seepage characteristics of structural planes of nonmaterial geotechnical materials in different strata contact zones, the formulas for calculating the deformation parameters and permeability coefficients of heterogeneous rock masses with single nonmaterial geotechnical materials are deduced theoretically, and the correctness and applicability of the formulas are verified by experiments. The rock mass sample selected in this paper is granite, which is simulated and analyzed by sandstone in the experiment. The results show that the permeability coefficients of coarse sandstone, fine sandstone, and heterogeneous rock mass are different under the same water pressure and confining pressure. This shows that the lithology on both sides of the nonmaterial geotechnical material surface has a significant influence on the permeability of the nonmaterial geotechnical material rock mass; the permeability coefficient of the nonmaterial geotechnical material rock mass decreases with the increase of confining pressure, the numerical change is limited to a certain confining pressure range, and the permeability coefficient tends to be stable when the confining pressure reaches a certain value. Comparing the theoretical calculation value of permeability coefficient of rock mass with the experimental result, it is found that the two values are in good agreement, which indicates the correctness and applicability of the theoretical calculation formula of permeability coefficient of rock mass of single intangible geotechnical material.

scholarly journals Experimental Analysis on Permeability Characteristics of Iron Tailings

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Deqing Gan ◽  
Xi Yang ◽  
Yunpeng Zhang
Keyword(s):  
Particle Size ◽  
Permeability Coefficient ◽  
Void Ratio ◽  
Average Particle Size ◽  
Average Particle ◽  
Fine Content ◽  
Permeability Characteristics ◽  
Permeability Coefficients ◽  
Effective Particle ◽  
The Relationship

The permeability characteristics of iron tailings are one of the important factors affecting the stability of the tailings dam. The permeability properties of undisturbed iron tailings and disturbed iron tailings were analyzed from various aspects such as FC value, gradation, particle size, specific surface area, and interparticle void ratio with water head test in laboratory. The results show that the permeability coefficients of undisturbed iron tailings and disturbed iron tailings are affected by the fine particles content (FC). The threshold of fine content is about 40%. The traditional formulas for calculating the permeability coefficient are applied. But the results are inaccurate. The relationship between permeability coefficient of the iron tailings (undisturbed iron tailings and disturbed iron tailings) and the nonuniform coefficient (Cu), the curvature coefficient (Cc), the average particle size, the weighted average particle size, the specific surface area, and the skeleton void ratio (es) is nonlinear. It is difficult to characterize the change of permeability coefficient when the fine content is large. However, the relationship between permeability coefficient of the iron tailings (undisturbed iron tailings and disturbed iron tailings) and the effective particle size and silt particles void ratio (ef) is linear. A formula was developed for the determination of permeability coefficient of iron tailings by analyzing the effective particle size and silt particles void ratio. And it is more accurate. The permeability coefficients of disturbed samples are slightly larger than the permeability coefficients of undisturbed sample. This is due to the destruction of the sedimentary structure of the tailings and increasing e. Maybe the R in the new formula is affected by the structure of iron tailings. This requires further research.

Study on Finite Element Algorithm of Jointed Rock Mass in Tunnel in Blasting and Model Building

2012 ◽  
Vol 204-208 ◽  
pp. 1331-1334
Author(s):  
Hong Yan Zhang ◽  
Qing Yang Yu ◽  
Neng Juan Zhou
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Model Building ◽  
Simulation Analysis ◽  
Jointed Rock ◽  
Rock Blasting ◽  
Lagrange Method ◽  
Joint Rock Mass ◽  
Relationship Of ◽  
The Relationship

It is a kind of effective way to study blasting to joint rock mass using the finite element method, in which the key is algorithm and model building. Comparing the relationship of explosive and blasting structure simulated by adopting Lagrange method and ALE method, the paper considers that Lagrange method is more close to practice, and could finish numerical simulation analysis of the intact rock blasting.

scholarly journals Experimental and Numerical Analysis of Stainless Steel Microtube in Flaring Process

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Tsung-Chia Chen ◽  
Wei-Kai Ceng
Keyword(s):  
Finite Element ◽  
Cone Angle ◽  
Experimental Result ◽  
Flow Rule ◽  
Forming Process ◽  
Element Analysis ◽  
Punch Load ◽  
The Coefficient Of Friction ◽  
Updated Lagrangian ◽  
The Relationship

This study, with experiments and comparisons, aims to analyze the difference of stainless (SUS316L) microtubes in the flaring forming among dies with various semicone angles (35°, 40°, 45°, 50°, and 55°). The flow rule by Prandtl-Reuss combined with the finite element deformation theory and updated Lagrangian formulation (ULF) is applied to establish the finite element analysis equation for an incremental elastoplastic deformation to simulate the microtube flaring process. The broadrminalgorithm is utilized in the forming process for the elastoplastic state and die contact. The simulation data allow acquiring the deformation traceability, the relationship between punch load and punch stroke, the distribution of stress and strain, the distribution of the thinnest thickness resulted from dies with different semicone angles, and the distribution of flaring radius caused by dies with distinct semicone angles in the forming process. The experimental result presents similar results to the relationship between punch load and punch stroke and the simulation of the coefficient of frictionμ=0.05, revealing the analysis being suitable for the analysis of microtube cone angle flaring process. The analysis and experimental results show that the thinnest thickness of the microtube increases with increasing semicone angles of dies and the maximal flaring radius of microtubes increases with increasing semicone angles of dies.

scholarly journals Transient Pulse Test for Non-Darcy Flow Behaviors and Hydromechanical Coupling Effect of Fractured Limestone

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
JianChao Cheng ◽  
YanLin Zhao ◽  
Yang Li ◽  
Tao Tan ◽  
Le Chang
Keyword(s):  
Permeability Coefficient ◽  
Coupling Effect ◽  
High Volume ◽  
Confining Pressure ◽  
Darcy Flow ◽  
Hydraulic Pressure ◽  
Acceleration Coefficient ◽  
Fractured Limestone ◽  
The Relationship ◽  
Volume Stress

In this paper, the transient pulse test is used to study the permeability and hydromechanical coupling effect of the fractured limestone. The permeability parameters (permeability, β factor of non-Darcy flow, and acceleration coefficient) of non-Darcy flow in fractured limestone are obtained by experimental data. The experimental results show that, in the process of transient seepage test of fractured Maokou limestone, the relationship between hydraulic pressure gradient and seepage velocity does not conform to Darcy’s law but meets Forchimer relationship. The relationship between hydraulic pressure difference and time can be fitted by quartic polynomial. The larger the confining pressure is, the more obvious the non-Darcy seepage effect of fractured rock seepage is. The seepage of rock fracture under high confining pressure is a highly nonlinear time-varying seepage. The permeability coefficient of rock decreases with the increase of volume stress. Under the action of low volume stress, the relationship between permeability coefficient and stress is more sensitive, while under the action of high volume stress, the relationship between permeability coefficient and volume stress is not significant. In the process of volume stress increasing, the β factor of non-Darcy flow appears negative. Under the action of low volume stress, the acceleration coefficient and β factor of non-Darcy flow increase, while under the action of high volume stress, the acceleration coefficient and β factor of non-Darcy flow decrease.

Theoretical Calculation and Simulation for Microcantilevers Based on SiC Epitaxial Layers

2019 ◽  
Vol 954 ◽  
pp. 26-30
Author(s):  
Xing Fang Liu ◽  
Guo Guo Yan ◽  
Zhan Wei Shen ◽  
Zheng Xin Wen ◽  
Jun Chen ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Resonant Frequency ◽  
Theoretical Calculation ◽  
Modal Analysis ◽  
Cantilever Beam ◽  
Vibration Mode ◽  
Epitaxial Layers ◽  
The Relationship ◽  
Element Method

The resonant frequency and Q factor of the SiC microcantilever were theoretically analyzed and calculated based on the stereotyped basic theories of the cantilever beam, and the relationship between the vibration mode and structure geometries was also simulated. Modal analysis by means of finite element method was performed on millimeter-, micron-and nanoscale microcantilevers, and the results showed that the smaller the microstructure was, the higher the resonant frequency can be obtained. The Q factor can be extracted from hamonic spectra after modal analysis, and the amplitude of Q factor was about 105. This paper shows that SiC epitaxial layers have great potential in microcantilevers.

scholarly journals Study on the Permeability of Weakly Cemented Sandstones

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
XianZhou Lyu ◽  
Zenghui Zhao ◽  
Xiaojie Wang ◽  
Weiming Wang
Keyword(s):  
Fracture Surface ◽  
Permeability Coefficient ◽  
Confining Pressure ◽  
Theoretical Formula ◽  
Single Fracture ◽  
Hydraulic Pressure ◽  
Test Results ◽  
Rock Masses ◽  
Heterogeneous Rock ◽  
Two Sides

Fractured rocks are a type of complex media that widely exist in various projects including energy, hydraulic, and underground space engineering, whose permeability properties are a hotspot in current rock mechanics domain. Aiming at investigating the seepage characteristics of the fracture surfaces in different rock strata, uniaxial compressive test and permeability test were performed on single-fracture homogenous and heterogeneous rocks. Specifically, rock’s physical and mechanical parameters were measured in uniaxial tests while the initial width of the single fracture was determined through CT scanning. In combination with test results and the calculation model of the displacement of single-fracture heterogeneous rock under triaxial stress condition, the calculation formula of the permeability coefficient of single-fracture heterogeneous rock was derived. Results show that hydraulic pressure in the fracture can affect the permeability coefficient of the fractured rock. Hydraulic fracturing effect occurred with the increase of hydraulic pressure in the fracture, which then generates slight normal deformations of the rock masses on both two sides of the fracture surface, decreases the contact area in the fracture, and leads to the increases of both fracture width and permeability coefficient. For single-fracture rock, the lithological properties of the rock masses on both two sides of the fracture surface impose significant effects on the permeability coefficient. Under same hydraulic pressure and confining pressure, the permeability coefficient of single-fracture coarse sandstone is greatest, followed by that of single-fracture heterogeneous rock, and finally by single-fracture fine sandstone. Theoretical calculation results agree well with the test results, suggesting that the derived theoretical formula can adequately describe the variation tendencies of permeability coefficient with confining pressure and hydraulic pressure in the fracture.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

Development and evaluation of trans-Amadi groundwater parameters: The integration of finite element techniques

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Finite Element ◽  
Polynomial Regression ◽  
Nitrate Concentration ◽  
Strong Relationship ◽  
Total Iron ◽  
Coefficient Of Determination ◽  
Port Harcourt ◽  
Polynomial Expression ◽  
The Relationship ◽  
Best Fit

Mathematical model was developed and evaluated to monitor and predict the groundwater characteristics of Trans-amadi region in Port Harcourt City. In this research three major components were considered such as chloride, total iron and nitrate concentration as well as the polynomial expression on the behavious on the concentration of each component was determined in terms of the equation of the best fit as well as the square root of the curve. The relationship between nitrate and distance traveled by Nitrate concentration by the model is given as Pc = 0.003x2 - 0.451x + 14.91with coefficient of determination, R² = 0.947, Chloride given as Pc = 0.000x2 - 0.071x + 2.343, R² = 0.951while that of Total Iron is given as Pc = 2E-05x2 - 0.003x + 0.110, R² = 0.930. All these show a strong relationship as established by Polynomial Regression Model. The finite element techniques are found useful in monitoring, predicting and simulating groundwater characteristics of Trans-amadi as well as the prediction on the variation on the parameters of groundwater with variation in time.

scholarly journals Stress wave propagation in different number of fissured rock mass based on nonlinear analysis

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiaoming Lou ◽  
Mingwu Sun ◽  
Jin Yu
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Confining Pressure ◽  
Displacement Discontinuity ◽  
Stress Wave Propagation ◽  
Theoretical Derivation ◽  
Mechanics Model ◽  
Fissured Rock ◽  
Deep Rock ◽  
Theoretical Accuracy

AbstractThe fissures are ubiquitous in deep rock masses, and they are prone to instability and failure under dynamic loads. In order to study the propagation attenuation of dynamic stress waves in rock mass with different number of fractures under confining pressure, nonlinear theoretical analysis, indoor model test and numerical simulation are used respectively. The theoretical derivation is based on displacement discontinuity method and nonlinear fissure mechanics model named BB model. Using ABAQUS software to establish a numerical model to verify theoretical accuracy, and indoor model tests were carried out too. The research shows that the stress attenuation coefficient decreases with the increase of the number of fissures. The numerical simulation results and experimental results are basically consistent with the theoretical values, which verifies the rationality of the propagation equation.

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