scholarly journals Comparative Study of Rainfall Infiltration into a Bare and a Grassed Unsaturated Expansive Soil Slope

2007 ◽  
Vol 47 (2) ◽  
pp. 207-217 ◽  
Author(s):  
C.W.W. Ng ◽  
L.T. Zhan
Keyword(s):  
Comparative Study ◽  
Expansive Soil ◽  
Rainfall Infiltration ◽  
Soil Slope ◽  
Unsaturated Expansive Soil

scholarly journals Performance estimation of a shallow foundation on an unsaturated expansive soil slope subjected to rainfall infiltration

2021 ◽  
Vol 337 ◽  
pp. 03009
Author(s):  
Mengxi Tan ◽  
Sai K. Vanapalli
Keyword(s):  
Slope Stability ◽  
Limit Equilibrium ◽  
Expansive Soil ◽  
Rainfall Infiltration ◽  
Performance Estimation ◽  
Shallow Foundation ◽  
Water Infiltration ◽  
Rational Approach ◽  
Soil Slope ◽  
Unsaturated Expansive Soil

In the last two decades, there has been a significant increase in infrastructure development on slopes of hilly regions of the world, due to population growth. There are many infrastructures on unsaturated expansive slopes, especially in semi-arid and arid regions. Rainfall infiltration is one of the major factors that contributes to the slope and infrastructure foundations failures on hilly slopes with unsaturated expansive soils. In the current study, a rational approach is proposed considering the combined influence of the foundation-slope behavior based on the principles of unsaturated soil mechanics. This is achieved by a novel numerical modelling approach using the commercial software Geo-studio to investigate the performance of strip foundation located on the top of the unsaturated expansive soil slope subjected to various rainfall infiltration conditions. Hydro-mechanical coupling analysis is conducted to evaluate the rainfall water infiltration influence combined with slope stability analysis using limit equilibrium method. Comparisons are made between both the foundation bearing capacity, slope stability before and after rainfall water infiltration. Different failure mechanisms of the foundation and slope system are presented with and without foundation loading for various rainfall scenarios. Results summarized in this paper are helpful for the geotechnical engineers for understanding the performance of shallow foundations on unsaturated expansive soil slopes considering the influence of rainfall infiltration conditions.

Field study of rainfall infiltration into a grassed unsaturated expansive soil slope

2007 ◽  
Vol 44 (4) ◽  
pp. 392-408 ◽  
Author(s):  
Tony LT Zhan ◽  
Charles WW Ng ◽  
Del G Fredlund
Keyword(s):  
Field Study ◽  
Water Content ◽  
Pore Water ◽  
Surface Runoff ◽  
Expansive Soil ◽  
Rainfall Infiltration ◽  
Slope Instability ◽  
Simulated Rainfall ◽  
Soil Slope ◽  
Unsaturated Expansive Soil

A full-scale field study was conducted to investigate the effects of rainfall infiltration on a natural grassed expansive soil slope in China. A 16 m wide × 28 m long area was selected for instrumentation. The instrumentation included jet-filled tensiometers, moisture probes, a tipping bucket rain gauge, and a vee-notch flow meter. One artificial rainfall event amounting to about 370 mm rain depth in total was applied to the slope. The monitored results suggested that there was about a 3 day delay in the response of surface runoff, pore-water pressure, and water content to the commencement of the simulated rainfall. The depth of influence of the rainfall, depending on the elevation along the slope, ranged from 2.8 to 3.5 m. Positive pore-water pressures were measured within the influence depth, and there existed significant subsurface downslope flow at the end of the simulated rainfall, particularly near the lower part of the slope. A comparison of infiltration rates between the grassed area and a bare area nearby indicated that the presence of grass significantly increased the infiltration rate and reduced surface runoff. The cracks and fissures developed in the unsaturated expansive soil played an important role in the hydrological process.Key words: expansive soil, slope instability, infiltration, vegetation cover, grass, soil suction, water content, unsaturated soil.

Performance of an unsaturated expansive soil slope subjected to artificial rainfall infiltration

Géotechnique ◽  
2003 ◽  
Vol 53 (2) ◽  
pp. 143-157 ◽  
Author(s):  
C. W. W. Ng ◽  
L. T. Zhan ◽  
C. G. Bao ◽  
D. G. Fredlund ◽  
B. W. Gong
Keyword(s):  
Expansive Soil ◽  
Rainfall Infiltration ◽  
Soil Slope ◽  
Artificial Rainfall ◽  
Unsaturated Expansive Soil

Instrumentation of an Unsaturated Expansive Soil Slope

2007 ◽  
Vol 30 (2) ◽  
pp. 12704 ◽  
Author(s):  
LD Suits ◽  
TC Sheahan ◽  
TLT Zhan ◽  
CWW Ng ◽  
DG Fredlund
Keyword(s):  
Expansive Soil ◽  
Soil Slope ◽  
Unsaturated Expansive Soil

Stability Analysis of Unsaturated Expansive Soil Slope Covered by Geo-Membrane

2015 ◽  
Vol 744-746 ◽  
pp. 597-600
Author(s):  
Hong Yu Zhang ◽  
Jiang Hu Chen ◽  
Wen Qing Wu ◽  
Jun Hua Wu
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Expansive Soil ◽  
Construction Process ◽  
Soil Slope ◽  
Seepage Field ◽  
Lower Slope ◽  
Unsaturated Expansive Soil

In view of the holes appearing in different area of geo-membrane when the geo-membrane technology is applied to the unsaturated expansive soil slope, the VADOSE/W is used to analyze the wetting-drying cycles caused by rainfall and evaporation on slopes covered by geo-membrane. The influence on the pore-water pressure and volume water content were discussed just caused by the holes. The results show that the hole is nearer to the toe of slope, its impact on the whole seepage field is greater. In addition, the hole appears on the top of slope that the wetting-drying cycle effect is remarkable. It is ensured that the integrity of the geo-membrane which in the lower slope and take some drainage measures in the construction process.

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