One-dimensional coupled model for landfill gas and water transport in layered unsaturated soil cover systems

2016 ◽  
Vol 17 (8) ◽  
pp. 667-676 ◽  
Author(s):  
Chi Guan ◽  
Hai-jian Xie ◽  
Zhan-hong Qiu ◽  
Yun-min Chen ◽  
Pei-xiong Chen
Keyword(s):  
Water Transport ◽  
Unsaturated Soil ◽  
Soil Cover ◽  
Landfill Gas ◽  
Coupled Model ◽  
One Dimensional ◽  
Cover Systems

scholarly journals One-Dimensional Vacuum Steady Seepage Model of Unsaturated Soil and Finite Difference Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Feng Huang ◽  
Jianguo Lyu ◽  
Guihe Wang ◽  
Hongyan Liu
Keyword(s):  
Finite Difference ◽  
Unsaturated Soil ◽  
Vacuum Pressure ◽  
Vacuum Field ◽  
One Dimensional ◽  
Steady Seepage ◽  
Basic Equations ◽  
The One ◽  
Seepage Law ◽  
Relationship Of

Vacuum tube dewatering method and light well point method have been widely used in engineering dewatering and foundation treatment. However, there is little research on the calculation method of unsaturated seepage under the effect of vacuum pressure which is generated by the vacuum well. In view of this, the one-dimensional (1D) steady seepage law of unsaturated soil in vacuum field has been analyzed based on Darcy’s law, basic equations, and finite difference method. First, the gravity drainage ability is analyzed. The analysis presents that much unsaturated water can not be drained off only by gravity effect because of surface tension. Second, the unsaturated vacuum seepage equations are built up in conditions of flux boundary and waterhead boundary. Finally, two examples are analyzed based on the relationship of matric suction and permeability coefficient after boundary conditions are determined. The results show that vacuum pressure will significantly enhance the drainage ability of unsaturated water by improving the hydraulic gradient of unsaturated water.

scholarly journals Computational modeling of the electromechanical response of a ventricular fiber affected by eccentric hypertrophy

2017 ◽  
Vol 8 (1) ◽  
pp. 185-209
Author(s):  
Fabrizio Del Bianco ◽  
Piero Colli Franzone ◽  
Simone Scacchi ◽  
Lorenzo Fassina
Keyword(s):  
Coupled Model ◽  
Electrical Current ◽  
Mechanoelectric Feedback ◽  
Isotonic Contraction ◽  
Strongly Coupled ◽  
One Dimensional ◽  
Electromechanical Responses ◽  
Eccentric Hypertrophy ◽  
Dimensional Finite Element ◽  
Simulation Results

AbstractThe aim of this work is to study the effects of eccentric hypertrophy on the electromechanics of a single myocardial ventricular fiber by means of a one-dimensional finite-element strongly-coupled model. The electrical current ow model is written in the reference configuration and it is characterized by two geometric feedbacks, i.e. the conduction and convection ones, and by the mechanoelectric feedback due to stretchactivated channels. First, the influence of such feedbacks is investigated for both a healthy and a hypertrophic fiber in case of isometric simulations. No relevant discrepancies are found when disregarding one or more feedbacks for both fibers. Then, all feedbacks are taken into account while studying the electromechanical responses of fibers. The results from isometric tests do not point out any notable difference between the healthy and hypertrophic fibers as regards the action potential duration and conduction velocity. The length-tension relationships show increased stretches and reduced peak values for tension instead. The tension-velocity relationships derived from afterloaded isotonic and quick- release tests depict higher values of contraction velocity at smaller afterloads. Moreover, higher maximum shortenings are achieved during the isotonic contraction. In conclusion, our simulation results are innovative in predicting the electromechanical behavior of eccentric hypertrophic fibers.

Soil–atmosphere modelling of an engineered soil cover for acid generating mine waste in a humid, alpine climate

2003 ◽  
Vol 40 (2) ◽  
pp. 276-292 ◽  
Author(s):  
D A Swanson ◽  
S L Barbour ◽  
G W Wilson ◽  
M O'Kane
Keyword(s):  
Water Transport ◽  
Research Program ◽  
Unsaturated Soils ◽  
Soil Cover ◽  
Acid Rock Drainage ◽  
Measurement Model ◽  
Acid Rock ◽  
Climate Conditions ◽  
Soil Covers ◽  
Soil Atmosphere

A research program studying the performance of soil covers at the Equity Silver Mine was initiated in 1992. This site is situated in the humid, alpine climate of north central British Columbia. A one-dimensional, fully coupled heat and water transport, soil–atmosphere flux model was developed as part of this research program to simulate the movement of liquid water and water vapour within a soil cover in response to rainfall and evapotranspiration. Predicted and measured conditions in the cover showed good agreement for a five-month period from June to November 1993. The modelling exercise showed that vapour flow was the dominant flow mechanism near the surface of the cover within a few days after the start of drying. This points out the necessity of being able to couple heat and water transport in soil cover analyses and design. The numerical modelling demonstrated that input parameters are readily attainable through field and laboratory measurement. Model predictions of extreme and mean climate conditions indicated that percolation through the cover system would be limited to approximately 2% of the annual precipitation and that oxygen flux through the cover would be reduced by approximately 98% from uncovered conditions.Key words: acid rock drainage, soil covers, unsaturated soils, infiltration, evapotranspiration, matric suction.

Settlement rate of foundations on unsaturated soils

1999 ◽  
Vol 36 (5) ◽  
pp. 940-946 ◽  
Author(s):  
Ernesto Ausilio ◽  
Enrico Conte
Keyword(s):  
Volume Change ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Shallow Foundations ◽  
Settlement Rate ◽  
One Dimensional ◽  
Consolidation Rate ◽  
Degree Of Consolidation ◽  
The One ◽  
External Loads

This paper deals with the one-dimensional consolidation of unsaturated soils due to the application of external loads. A simple equation is derived that enables one to predict the rate of settlement of shallow foundations with time. This equation uses the constitutive relationships proposed by Fredlund and Morgenstern to define the volume change of unsaturated soils, and relates the settlement rate to the average degree of consolidation for both the water and air phases. A series of examples is shown to demonstrate the feasibility and usefulness of the derived equation. Key words: one-dimensional consolidation, unsaturated soil, degree of consolidation, rate of settlement.

Numerical Simulation of Unsaturated Evaporation and Drying Front Advancing in One-Dimensional Soil Columns

2013 ◽  
Vol 353-356 ◽  
pp. 730-734
Author(s):  
Zhang Hua ◽  
Gao Kang ◽  
Xiong Yi
Keyword(s):  
Great Influence ◽  
Coupled Model ◽  
Dry Density ◽  
Soil Columns ◽  
Total Evaporation ◽  
One Dimensional ◽  
Actual Evaporation ◽  
Constant Rate ◽  
Three Stages ◽  
Simulation Results

A coupled model of heat-moisture flow with Penman-Wilson evaporation boundary condition is used for simulating evaporation processes in three 1D vertical columns with different dry densities. The simulation results show that unsaturated evaporation process has three stages, i.e. constant-rate stage, falling-rate stage and residual stage. The depth of drying front has a great influence on soil actual evaporation. The actual evaporation decreases as the drying front advancing downward. The total evaporation decreased with the increase of soil dry density. The velocity of drying front advancing in the soil of higher dry density is faster than that of lower dry density.

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