scholarly journals The Influence of Moisture Content on the Time-Dependent Characteristics of Rock Material and Its Application to the Construction of a Tunnel Portal

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaojun Liu ◽  
Chao Yang ◽  
Jing Yu
Keyword(s):  
Moisture Content ◽  
Deformation Behaviour ◽  
Creep Behaviour ◽  
Three Dimensional ◽  
Viscosity Coefficient ◽  
Guizhou Province ◽  
Creep Model ◽  
Low Grade ◽  
Saturation Degree ◽  
Moisture Contents

Uniaxial compression creep experiments were carried out for low-grade metamorphic slate samples (located in the southeastern area of Guizhou province, China) with different moisture contents, using an Instron electric-fluid servo-compression machine. Based on the experimental results, a detailed analysis was made of the effect of moisture content on the strength and deformation behaviour of the slate specimens. The three-parameter generalised Kelvin model was identified to describe the creep behaviour of the low-grade metamorphic slate with different moisture contents. There is an approximately linear negative correlation between the elastic modulus and the saturation degree, and the viscoelastic modulus and viscosity coefficient show a negative exponent correlation with the saturation degree. The Kelvin creep model considering the moisture degradation effect was established and a three-dimensional finite difference model was developed with the softwareFLAC3Dto validate the creep model. A three-dimensional numerical analysis was then performed to simulate the tunnel excavation process. The results show that the influence of moisture and creep of the surrounding rocks is needed for estimating the deformation of complex tunnel portals.

Propagation velocity model of stress waves in larch wood (Larix gmelinii) three-dimensional space with different moisture contents

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6680-6695
Author(s):  
Xiwen Wei ◽  
Liping Sun ◽  
Hongjv Zhou ◽  
Yang Yang ◽  
Yifan Wang ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wave Velocity ◽  
Stress Wave ◽  
Propagation Velocity ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Stress Waves ◽  
Moisture Contents ◽  
Direction Angle ◽  
Stress Wave Velocity

Based on the effects of stress wave propagation in larch (Larix gmelinii) wood, the propagation mechanism of stress wave was explored, and a theoretical model of the propagation velocity of stress waves in the three-dimensional space of wood was developed. The cross and longitudinal propagation velocities of stress wave were measured in larch wood under different moisture contents (46% to 87%, 56% to 96%, 20% to 62%, and 11% to 30%) in a laboratory setting. The relationships between the propagation velocity of stress waves and the direction angle or chord angle with different moisture contents were analyzed, and the three-dimensional regression models among four parameters were established. The analysis results indicated that under the same moisture content, stress wave velocity increased as the direction angle increased and decreased as chord angle increased, and the radial velocity was the largest. Under different moisture contents, stress wave velocity gradually decreased as moisture content increased, and the stress wave velocity was more noticeably affected by moisture content when moisture content was below the fiber saturation point (FSP, 30%). The nonlinear regression models of the direction angle, chord angle, moisture content, and the propagation velocity of stress wave fit the experiment data well (R2 ≥ 0.97).

Study on Test of the Influence of Moisture Content on Creep Property of Sandy Slate Coarse-Grained Soil

2013 ◽  
Vol 405-408 ◽  
pp. 1733-1738 ◽  
Author(s):  
Qun Liu ◽  
Xiang Wang ◽  
Xiao Dong Song
Keyword(s):  
Moisture Content ◽  
Creep Test ◽  
Creep Property ◽  
Coarse Grained ◽  
Creep Model ◽  
Moisture Contents ◽  
Compression Creep ◽  
Moisture Conditions ◽  
Coarse Grained Soil

Coarse-grained soil is widely used in subgrade engineering, creep property of which is the important factor that affects long-term settlement of fill embankment. The creep property of sandy slate coarse-grained soil under different moisture conditions is analyzed through uniaxial compression creep test on influence rule of moisture content on creep of coarse-grained soil. Relations between moisture contents and creep parameters are studied on the basis of H-K Creep Model. It turns out that moisture content is the important factor that affects creep property of sandy slate coarse-grained soil and using dry or saturated coarse-grained soil is able to decrease long-term settlement of embankment.

RAPID DETERMINATION OF MOISTURE IN GRAIN: II. CALIBRATION AND COMPARISON OF ELECTRICAL MOISTURE METERS WITH VACUUM OVEN FOR HARD RED SPRING WHEAT

1934 ◽  
Vol 11 (4) ◽  
pp. 409-447 ◽  
Author(s):  
W. H. Cook ◽  
J. W. Hopkins ◽  
W. F. Geddes
Keyword(s):  
Moisture Content ◽  
Temperature Coefficient ◽  
Calibration Curve ◽  
Rapid Determination ◽  
Low Grade ◽  
Vacuum Oven ◽  
Hard Red Spring Wheat ◽  
Moisture Contents ◽  
Experimental Errors ◽  
General Reliability

The electrical moisture meters studied were: the Burton-Pitt, Davies, Limbrick, hand-operated and motor-operated Tag-Heppenstall. The Burton-Pitt is a "dielectric" type; all the others depend on the resistance principle.The calibration curve for the Burton-Pitt instrument is parabolic within the range 11.0 to 17.0% moisture. The resistance type instruments all show a linear relation between moisture content and the logarithm of the resistance at moisture contents below 17.0%, and a parabolic relation at higher moisture contents. The accuracy of the meters, as determined by the experimental errors and the standard error of prediction of the vacuum oven moisture, decreases in the following order within the moisture range, 11.0 to 17.0%: motor-operated Tag-Heppenstall, Limbrick, hand-operated Tag-Heppenstall, Burton-Pitt and Davies. At higher moisture contents than 17.0% the Burton-Pitt and Davies instruments are definitely unreliable, and the remaining meters are also less precise.The temperature coefficient of the wheat-instrument system was found to be appreciably different from that of the wheat alone in the Limbrick and Burton-Pitt. The temperature coefficient was also found to differ somewhat in different moisture ranges. The effect of humidity is most pronounced in the Limbrick, but is in all instruments small in comparison with that of temperature. The limited number of low grade samples studied appeared to follow the same calibration curve as high grade samples in all meters and 28 samples of the hard-kernelled variety Garnet were also found to follow the calibration curve deduced from the general reliability experiments in all meters, with the exception of the hand-operated Tag-Heppenstall. The discrepancy with this meter is not great and can be attributed to the roll space being unsuitable for this hard-kernelled variety.The moisture range satisfactorily covered by the instruments decreases in the order: motor-operated Tag-Heppenstall, hand-operated Tag-Heppenstall, Limbrick, Burton-Pitt and Davies. In all cases the upper limit is finally determined by the increasing inaccuracy of the meter, rather than by its physical range, which is limited at 21.5% moisture with the Limbrick only when used at the highest sensitivity. With wheat below 11.0% moisture, only the Burton-Pitt and Tag-Heppenstall instruments can be used, and the calibration curve for the Burton-Pitt obtained with wheat of higher moisture content cannot be extrapolated over this lower range.

The Smoulder Stream of Cigarettes / Zur Kenntnis des Glimmstromes von Cigaretten

1965 ◽  
Vol 3 (2) ◽  
Author(s):  
F. Seehofer ◽  
W. Schulz
Keyword(s):  
Moisture Content ◽  
Spatial Position ◽  
High Yield ◽  
Physical Conditions ◽  
Moisture Contents ◽  
Cigarette Paper ◽  
First Time

AbstractThe phenomenon of the smoulder stream flowing through the cigarette during smouldering and during the puff intervals is demonstrated for the first time and its dependence upon physical conditions is examined. The volume of the smoulder stream can amount up to 180 ml per cigarette. Increasing draw resistance of the cigarette and augmenting moisture content of the tobacco as well as perforation of the cigarette paper have a decreasing effect on volume and velocity of the smoulder stream. The porosity of the cigarette paper has no perceptible influence. The spatial position of the cigarette affects volume and velocity of the smoulder stream. The influence exercised by the smoulder stream on the yields of total condensate, nicotine, phenols, aldehydes, and acroleine when the cigarette tip is open during the puff intervals is determined. When the moisture contents of the tobacco were extremely high, yield decreases reaching 50 % could be observed.

Developing a Linearization Method to Determine Optimum Blending for Surimi with Varied Moisture Contents Using Linear Programming

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Hyeon W. Park ◽  
Jae W. Park ◽  
Won B. Yoon
Keyword(s):  
Linear Programming ◽  
Moisture Content ◽  
Standard Procedure ◽  
Unit Cost ◽  
Linearization Method ◽  
Model Parameters ◽  
Additional Information ◽  
Moisture Contents ◽  
Design Variables ◽  
Critical Moisture

AbstractNovel algorithm to determine the least cost formulation of a surimi blend was developed using linear programming (LP). Texture properties and the unit cost of surimi blend at the target moisture content were used as constraint functions and the objective function, respectively. The mathematical models to describe the moisture content dependence of the ring tensile properties were developed using critical moisture content, and the model parameters were used for the least cost LP (LCLP) model. The LCLP model successfully predicted the quality of surimi blend. Sensitivity analysis was used to obtain an additional information when the perturbations of design variables are provided. A standard procedure to determine the least cost formulation for blending surimi with varied moisture contents was systematically developed.

Modeling of Thermoplastic Materials for the Process-Simulation of Press-Fit Interconnections on Moulded Interconnected Devices

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Thomas Fellner ◽  
Elena Zukowski ◽  
Jürgen Wilde ◽  
H. Kück ◽  
H. Richter ◽  
...  
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Base Material ◽  
Creep Model ◽  
Assembly Process ◽  
Temperature Dependent ◽  
Reliability Modeling ◽  
Finite Element Software ◽  
Press Fit ◽  
Temperature Loads

This investigation is aimed at the modeling of both the fabrication process and the reliability of press-fit interconnections on moulded interconnect devices (MID). These are multifunctional three-dimensional substrates, produced by thermoplastic injection moulding for large-series applications. The assembly process and subsequently the durability of press-fit interconnections has been modeled and proved with a finite element software. Especially, a simulation tool for process optimizations was created and applied. In order to obtain realistic results, a creep model for the investigated base material, a liquid-crystal polymer (LCP), was generated and verified by experiments. Required friction coefficients between metal pin and base material were determined by adapting simulations and experiments. Retention forces of pins pressed into substrate holes during as well after the assembly process, and after temperature loads were predicted by simulations. Additionally, the decreasing extraction forces over time due to creep in the thermoplastic base material have been predicted for different storage temperatures as well with finite element analyses. Following, the numerical results of the process and reliability modeling were verified by experiments. It is concluded that the behavior of the mechanical contact of the pin-substrate system, can be suitably described time- and temperature-dependent.

Generation of steady longitudinal vortices in hypersonic boundary layer

2013 ◽  
Vol 729 ◽  
pp. 702-731 ◽  
Author(s):  
A. I. Ruban ◽  
M. A. Kravtsova
Keyword(s):  
Boundary Layer ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Viscosity Coefficient ◽  
Momentum Equation ◽  
The Body ◽  
Nonlinear Behaviour ◽  
Hypersonic Boundary Layer ◽  
Stagnation Temperature ◽  
Characteristic Distance

AbstractIn this paper we study the three-dimensional perturbations produced in a hypersonic boundary layer by a small wall roughness. The flow analysis is performed under the assumption that the Reynolds number, $R{e}_{0} = {\rho }_{\infty } {V}_{\infty } L/ {\mu }_{0} $, and Mach number, ${M}_{\infty } = {V}_{\infty } / {a}_{\infty } $, are large, but the hypersonic interaction parameter, $\chi = { M}_{\infty }^{2} R{ e}_{0}^{- 1/ 2} $, is small. Here ${V}_{\infty } $, ${\rho }_{\infty } $ and ${a}_{\infty } $ are the flow velocity, gas density and speed of sound in the free stream, ${\mu }_{0} $ is the dynamic viscosity coefficient at the ‘stagnation temperature’, and $L$ is the characteristic distance the boundary layer develops along the body surface before encountering a roughness. We choose the longitudinal and spanwise dimensions of the roughness to be $O({\chi }^{3/ 4} )$ quantities. In this case the flow field around the roughness may be described in the framework of the hypersonic viscous–inviscid interaction theory, also known as the triple-deck model. Our main interest in this paper is the nonlinear behaviour of the perturbations. We study these by means of numerical solution of the triple-deck equations, for which purpose a modification of the ‘skewed shear’ technique suggested by Smith (United Technologies Research Center Tech. Rep. 83-46, 1983) has been used. The technique requires global iterations to adjust the viscous and inviscid parts of the flow. Convergence of such iterations is known to be a major problem in viscous–inviscid calculations. In order to achieve improved stability of the method, both the momentum equation for the viscous part of the flow, and the equations describing the interaction with the flow outside the boundary layer, are treated implicitly in this study. The calculations confirm the fact that in this sort of flow the perturbations are capable of propagating upstream in the boundary layer, resulting in a perturbation field which surrounds the roughness on all sides. We found that the perturbations decay rather fast with the distance from the roughness everywhere except in the wake behind the roughness. We found that if the height of the roughness is small, then the perturbations also decay in the wake, though much more slowly than outside the wake. However, if the roughness height exceeds some critical value, then two symmetric counter-rotating vortices form in the wake. They appear to support themselves and grow as the distance from the roughness increases.

scholarly journals Experimental Study on the Softening Characteristics of Sandstone and Mudstone in Relation to Moisture Content

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Gui-chen Li ◽  
Chong-chong Qi ◽  
Yuan-tian Sun ◽  
Xiao-lin Tang ◽  
Bao-quan Hou
Keyword(s):  
Moisture Content ◽  
Vertical Displacement ◽  
Surface Porosity ◽  
Shear Tests ◽  
Moisture Contents ◽  
Dynamic Finite Element ◽  
Rock Types ◽  
Underground Roadway ◽  
The Stability ◽  
Kinetics Of

The kinetics of fluid-solid coupling during immersion is an important topic of investigation in rock engineering. Two rock types, sandstone and mudstone, are selected in this work to study the correlation between the softening characteristics of the rocks and moisture content. This is achieved through detailed studies using scanning electron microscopy, shear tests, and evaluation of rock index properties during exposure to different moisture contents. An underground roadway excavation is simulated by dynamic finite element modeling to analyze the effect of moisture content on the stability of the roadway. The results show that moisture content has a significant effect on shear properties reduction of both sandstone and mudstone, which must thus be considered in mining or excavation processes. Specifically, it is found that the number, area, and diameter of micropores, as well as surface porosity, increase with increasing moisture content. Additionally, stress concentration is negatively correlated with moisture content, while the influenced area and vertical displacement are positively correlated with moisture content. These findings may provide useful input for the design of underground roadways.

Heat and Mass Diffusion Including Shrinkage and Hygrothermal Stress during Drying of Holed Ceramics Bricks

2011 ◽  
Vol 312-315 ◽  
pp. 971-976 ◽  
Author(s):  
J. Barbosa da Silva ◽  
G. Silva Almeida ◽  
W.C.P. Barbosa de Lima ◽  
Gelmires Araújo Neves ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Moisture Content ◽  
Three Dimensional ◽  
Average Moisture Content ◽  
Stress Distributions ◽  
Drying Process ◽  
Convective Boundary ◽  
Volume Method ◽  
Hygrothermal Stress ◽  
Thermo Physical Properties ◽  
Good Agreement

The Aim of this Work Is to Present a Three-Dimensional Mathematical Modelling to Predict Heat and Mass Transport inside the Industrial Brick with Rectangular Holes during the Drying Including Shrinkage and Hygrothermalelastic Stress Analysis. the Numerical Solution of the Diffusion Equation, Being Used the Finite-Volume Method, Considering Constant Thermo-Physical Properties and Convective Boundary Conditions at the Surface of the Solid, it Is Presented and Analyzed. Results of the Temperature, Moisture Content and Stress Distributions, and Drying and Heating Kinetics Are Shown and Analyzed. Results of the Average Moisture Content and Surface Temperature of the Brick along the Drying Process Are Compared with Experimental Data (T = 80.0oC and RH = 4.6 %) and Good Agreement Was Obtained. it Was Verified that the Largest Temperature, Moisture Content and Stress Gradients Are Located in the Intern and External Vertexes of the Brick.

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