Experimental Study of Water Infiltration in Unsaturated Horizontal Sand Columns under Various Air Confinement Conditions

The process of water infiltration into initially dry sand was studied in horizontal sand columns under various airtight conditions. To investigate the interrelations among water inflow behavior, air pressure, air confinement effect, and vent effectiveness in unsaturated porous media experiencing dynamic infiltration, a total of five dynamic infiltration experiments with fixed inlet water pressure were performed with different air vents open or closed along the column length. Visualizations of the infiltration process were accompanied by measurements of water saturation, air pressure, and accumulated water inflow. In a column system with an open end, the absence of air pressure buildup reveals that the vent at the column end can significantly reduce the internal air pressure effects during infiltration, and the air phase can be ignored for this case. However, in columns with a tight end, the coupled air and water flow processes can be divided into two completely different periods. Before the water front passed by the most distant open vent, the internal air pressure effects on retarding dynamic infiltration are negligible, similar to the open end case. After this period, the open vents can certainly influence the inflow behavior by functioning as air outlets while they cannot equilibrate pore air pressure with the atmospheric pressure. The remaining air ahead of the front will be gradually confined and compressed, and the significant increase in air pressure highlights the great role of air pressure buildup in reducing the water infiltration rate. The closer the last open vent was to the water inlet, the higher was the increase in air pressure and the greater was the delaying effect on water infiltration. This work may extend the experimental study of water infiltration into the unsaturated soils with different airtight conditions and provide experimental evidence on these coupled mechanisms among the water and air phases in soils.

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Experimental Study of Air Pressure Effects on Natural Convection From a Horizontal Cylinder

Heat Transfer Engineering ◽

10.1080/01457632.2012.654448 ◽

2012 ◽

Vol 33 (10) ◽

pp. 878-884 ◽

Cited By ~ 4

Author(s):

Reza Hosseini ◽

Maysam Saidi

Keyword(s):

Experimental Study ◽

Natural Convection ◽

Horizontal Cylinder ◽

Air Pressure ◽

Pressure Effects

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Consolidation of Unsaturated Soils due to Dissipation of Pore-Air Pressure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.580-583.160 ◽

2014 ◽

Vol 580-583 ◽

pp. 160-164

Author(s):

Hao Feng Xu ◽

Wen Jun Wang ◽

Zhi Xiang Zha

Keyword(s):

Differential Equation ◽

Unsaturated Soils ◽

Laboratory Tests ◽

Pore Water Pressure ◽

Water Pressure ◽

Nonlinear Partial Differential Equation ◽

Air Pressure ◽

Saturated Soils ◽

One Dimensional ◽

Special Case

One-dimensional consolidation equation of unsaturated soils was derived in order to solve this special case of consolidation. The presented equation, not similar to Terzaghi’s equation, is a type of absolute nonlinear partial differential equation, and it was solved by finite difference method. An example was analyzed and the case of incompressible fluid consolidation was compared. Finally the experimental results from laboratory tests reported in the literature, was fitted by the presented equation, and the agreement was good. The results show that (1) the process of pore-air pressure dissipation is similar to that of pore-water pressure of saturated soils; (2) the compressibility of pore fluid is not an advantageous factor to quicken the consolidation; (3) the presented equation is effective to analyze the process of consolidation of unsaturated soils which consolidate mainly due to the dissipation of pore-air pressure.

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Analysis of Tunnel Water Inrush Considering the Influence of Surrounding Rock Permeability Coefficient by Excavation Disturbance and Ground Stress

Applied Sciences ◽

10.3390/app11083645 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3645

Author(s):

Helin Fu ◽

Pengtao An ◽

Long Chen ◽

Guowen Cheng ◽

Jie Li ◽

...

Keyword(s):

Permeability Coefficient ◽

Water Pressure ◽

Water Inrush ◽

Surrounding Rock ◽

Water Inflow ◽

Calculation Error ◽

External Water Pressure ◽

Ground Stress ◽

External Water ◽

Inflow Prediction

Affected by the coupling of excavation disturbance and ground stress, the heterogeneity of surrounding rock is very common. Presently, treating the permeability coefficient as a fixed value will reduce the prediction accuracy of the water inflow and the external water pressure of the structure, leading to distortion of the prediction results. Aiming at this problem, this paper calculates and analyzes tunnel water inflow when considering the heterogeneity of permeability coefficient of surrounding rock using a theoretical analysis method, and compares with field data, and verifies the rationality of the formula. The research shows that, when the influence of excavation disturbance and ground stress on the permeability coefficient of surrounding rock is ignored, the calculated value of the external water force of the tunnel structure is too small, and the durability and stability of the tunnel are reduced, which is detrimental to the safety of the structure. Considering the heterogeneity of surrounding rock, the calculation error of water inflow can be reduced from 27.3% to 13.2%, which improves the accuracy of water inflow prediction to a certain extent.

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Analysis of Seepage Characteristics of a Foundation Pit with Horizontal Waterproof Curtain in Highly Permeable Strata

Water ◽

10.3390/w13091303 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1303

Author(s):

Chenghua Shi ◽

Xiaohe Sun ◽

Shengli Liu ◽

Chengyong Cao ◽

Linghui Liu ◽

...

Keyword(s):

Hydraulic Conductivity ◽

Theoretical Calculation ◽

Calculation Method ◽

Design Method ◽

Water Pressure ◽

Water Inflow ◽

Deep Foundation ◽

Foundation Pit ◽

Deep Foundation Pit ◽

Seepage Characteristics

At present, jet-grouted horizontal waterproof curtain reinforcement has become an essential method for deep foundation pit groundwater control. However, there is still a lack of an effective theoretical calculation method for horizontal waterproof curtain reinforcement, and there is little research on the seepage laws of foundation pits under different horizontal waterproof curtain conditions. Based on Darcy’s seepage theory, theoretical analysis models of deep foundation pit seepage were established considering the effect of a horizontal curtain in a highly permeable formation. Through the established models, the calculation method of the water inflow and the water pressure under the condition of a horizontal curtain was derived. Then through indoor tests, the reliability of the theoretical calculation method was verified. Furthermore, the established theoretical calculation method is used to analyze the influence of various factors on the water inflow and the water pressure, such as the ratio of hydraulic conductivity of the horizontal curtain to surrounding soil, thickness, and reinforcement position of the horizontal curtain. It is found that the hydraulic conductivity ratio has the most significant influence on the seepage characteristics of the foundation pit. Finally, the design method was applied to an example of the horizontal waterproof curtain of the foundation pit, which is located at Juyuanzhou Station in Fuzhou (China). The water inflow per unit area is 0.36 m3/d in the foundation pit, and this implies that the design method of the horizontal waterproof curtain applied for the excavation case is good and meets the requirements of design and safety.

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Experimental study and constitutive modeling of volume change behavior in unsaturated soils

Bulletin of Engineering Geology and the Environment ◽

10.1007/s10064-020-01943-3 ◽

2020 ◽

Vol 80 (1) ◽

pp. 679-689

Author(s):

Wugang Li ◽

Qing Yang ◽

Zhijia Xue ◽

Wenhua Liu ◽

Yuan Hua

Keyword(s):

Experimental Study ◽

Volume Change ◽

Constitutive Modeling ◽

Unsaturated Soils ◽

Change Behavior ◽

Volume Change Behavior

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Experimental study on effective microwave heating/fracturing of coal with various dielectric property and water saturation

Fuel Processing Technology ◽

10.1016/j.fuproc.2020.106378 ◽

2020 ◽

Vol 202 ◽

pp. 106378 ◽

Cited By ~ 4

Author(s):

Guang Xu ◽

Jinxin Huang ◽

Guozhong Hu ◽

Nan Yang ◽

Jieqi Zhu ◽

...

Keyword(s):

Experimental Study ◽

Dielectric Property ◽

Microwave Heating ◽

Water Saturation

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Effects of Macroscopic Pores on the Damping Behaviors of Metal Materials

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.66-68.1155 ◽

2011 ◽

Vol 66-68 ◽

pp. 1155-1162

Author(s):

Jian Ning Wei ◽

Gen Mei Li ◽

Li Ling Zhou ◽

Xue Yun Zhou ◽

Jian Min Yu ◽

...

Keyword(s):

Internal Friction ◽

Pure Aluminum ◽

Air Pressure ◽

Damping Capacity ◽

Infiltration Process ◽

Pressure Infiltration ◽

Temperature Range ◽

Commercially Pure ◽

Damping Behavior ◽

Metal Materials

A large number of macroscopic pores were introduced into commercially pure aluminum (Al) and Zn-Al eutectoid alloy by air pressure infiltration process to comparatively study the influence of macroscopic pores on the damping behaviors of the materials. Macroscopic pores size are on the order of a millimetre (0.5~1.4mm) and in large proportions, typically high 76vol.%. The damping behavior of the materials is characterized by internal friction (IF). The IF was measured on a multifunction internal friction apparatus (MFIFA) at frequencies of 0.5, 1.0 and 3.0 Hz over the temperature range of 25 to 400 °C, while continuously changing temperature. The damping capacity of the metal materials is shown to increase with introducing macroscopic pores. Finally, the operative damping mechanisms in the metal materials with macroscopic pores were discussed in light of IF measurements.

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Theory of a Time Domain Boundary Element Development for the Dynamic Analysis of Coupled Multiphase Porous Media

Journal of Multiscale Modelling ◽

10.1142/s175697371750007x ◽

2017 ◽

Vol 08 (03n04) ◽

pp. 1750007

Author(s):

Pooneh Maghoul ◽

Behrouz Gatmiri

Keyword(s):

Boundary Element ◽

Time Domain ◽

Unsaturated Soils ◽

Water Pressure ◽

Domain Boundary ◽

Fundamental Solutions ◽

Element Formulation ◽

Inertia Effects ◽

Coupled Equations ◽

The Time Domain

This paper presents an advanced formulation of the time-domain two-dimensional (2D) boundary element method (BEM) for an elastic, homogeneous unsaturated soil subjected to dynamic loadings. Unlike the usual time-domain BEM, the present formulation applies a convolution quadrature which requires only the Laplace-domain instead of the time-domain fundamental solutions. The coupled equations governing the dynamic behavior of unsaturated soils ignoring contributions of the inertia effects of the fluids (water and air) are derived based on the poromechanics theory within the framework of a suction-based mathematical model. In this formulation, the solid skeleton displacements [Formula: see text], water pressure [Formula: see text] and air pressure [Formula: see text] are presumed to be independent variables. The fundamental solutions in Laplace transformed-domain for such a dynamic [Formula: see text] theory have been obtained previously by authors. Then, the BE formulation in time is derived after regularization by partial integrations and time and spatial discretizations. Thereafter, the BE formulation is implemented in a 2D boundary element code (PORO-BEM) for the numerical solution. To verify the accuracy of this implementation, the displacement response obtained by the boundary element formulation is verified by comparison with the elastodynamics problem.

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