Field and laboratory experimental study of water infiltration in cracked soil

2009 ◽  
Author(s):  
Chin Pang Kwong
Keyword(s):  
Experimental Study ◽  
Water Infiltration ◽  
Cracked Soil

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

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Meng Chen ◽  
Zhifang Zhou ◽  
Brent Sleep ◽  
Xingxing Kuang ◽  
Li Mingwei ◽  
...  
Keyword(s):  
Experimental Study ◽  
Unsaturated Soils ◽  
Water Saturation ◽  
Water Pressure ◽  
Air Pressure ◽  
Pressure Effects ◽  
Water Infiltration ◽  
Water Inflow ◽  
Infiltration Process ◽  
Pressure Buildup

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.

Permeability tensor and representative elementary volume of saturated cracked soil

2009 ◽  
Vol 46 (8) ◽  
pp. 928-942 ◽  
Author(s):  
J. H. Li ◽  
L. M. Zhang ◽  
Y. Wang ◽  
D. G. Fredlund
Keyword(s):  
Ground Surface ◽  
Representative Elementary Volume ◽  
Permeability Tensor ◽  
Water Infiltration ◽  
Elementary Volume ◽  
Statistical Parameters ◽  
Crack Network ◽  
Soil Matrix ◽  
Preferential Pathways ◽  
Cracked Soil

Cracks are prevalent in near-ground-surface soils and provide preferential pathways for fluid flow. Cracks increase water infiltration or contaminant solute transport into soils. This paper studies the development of a permeability tensor and a representative elementary volume (REV) for saturated cracked soils. First, a method of generating random crack networks based on the statistical parameters of the crack geometry is presented. Then, the permeability tensor and REV for a crack network are studied by modeling water flow through the generated random crack networks. Finally, the permeability tensor for a cracked soil is obtained by combining the crack network and the soil matrix, and the properties of the permeability tensor and the REV for the cracked soils are investigated. Results show that the permeability tensor can be used to represent the permeability anisotropy of a cracked soil. An REV can be readily established when the crack network is relatively dense. An REV can be defined and the contribution of the crack network to permeability is small when a crack network exists in homogeneous sands. An REV is harder to establish and the hydraulic conductivity is dominated by the random crack network when a sparse crack network exists in clays.

scholarly journals Experimental study of water infiltration on an unsaturated soil-geosynthetic system

2015 ◽  
Author(s):  
Edwin Fabián García-Aristizábal ◽  
◽  
Carlos Alberto Vega-Posada ◽  
Alba Nury Gallego-Hernández ◽  
◽  
...  
Keyword(s):  
Experimental Study ◽  
Unsaturated Soil ◽  
Water Infiltration

Water infiltration in a cracked soil considering effect of drying-wetting cycles

2020 ◽  
pp. 125640
Author(s):  
Qing Cheng ◽  
Chao-Sheng Tang ◽  
Dan Xu ◽  
Hao Zeng ◽  
Bin Shi
Keyword(s):  
Water Infiltration ◽  
Cracked Soil

Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

1995 ◽  
Vol 53 ◽  
pp. 636-637
Author(s):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe
Keyword(s):  
Experimental Study ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Optical Parameters ◽  
Beam Tilting ◽  
Illumination Method ◽  
Restoration Method ◽  
Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

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